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VE OUR UDIO?

TE HNOLOGY - M DEC> - S liEF.lE

UILD A NEGATIVE-IONGENERATORExperiment with high-voltageelectronics and the effectsof negative ions

BUILD A SWEEP/MARKER GENERATORTest your audio amplifier andf ilter circuits

YOUR PCI TAU IVERSALFRED ENCY COUNTERBuild this plug-in card~or your lab computer

HO TROUBLESHOOTING TIPSHow to use the horizontaloutput transistor pulse todiagnose TV troubles

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ELECTRONICS STA DARDSA refresher course looks att he basis of our measurements

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$2.95 U.S.$3.75 CAN

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PHILIPS

Two displays.One great meter.

FLUKE 45DUAL DISPLAY MULTIMETER

FROM THE WORLD LEADERIN DIGITALMULTIMETERS

John Fluke Mfg . Co., Inc. P.O. Box 9090 MIS 250C Everett.WA 98206U.S.: 206-356-5400 Canada: 416-890-7600 Other Countries:206-356-5500 ~ Copyright 1989.1990 John FlukeMig Co"Inc.Allrights reserved . Ad no. 00015. IBM PCisaregiste red trademark01International Business Machines Corporation .

Dual displays provide two accuratemeasurements. Combined with 16different measurement capabilities.The Fluke 45is making people take asecond look.The Fluke 45has the specs toget thejob done right. 0.02% basic dc voltageaccuracy and 100,000 count resolution onboth displays. Basic dc current accuracy is0.05%, making the 45 ideal for servicing4-20 mA current loops.The Fluke 45 mea­surestrue-rms voltage and current, includingac+dc. Closed-case calibration simplifiesthe calibration process and increases uptime.Twice as much information.The 5-digit,100,000 count dual displaysgive you more information in less time-andwith less effort. For example, measure theVDC output of apower supply while measur­ing the VAC ripple. Or check the amplitudeand frequency of an AC signal. From asingletest connection!

More measurement combinations.With the Fluke 45 complexmeasurementsbecome simple, with standard features like a1MHz frequency counter, Min Max, limitstesting (Hi /Lo/Pass),Touch Hold®andRelative modes.There are 21 different ref­erence impedances for dB measurements;inthe 2il to 16il ranges,audio power canbe automatically displayed in watts.Thevariety of electrical parameters, measurementfunctions and display combinations isincredible.Even an RS·232 interface isstandard.Connecting the Fluke 45 to PCs, RS-232printers and modems isas easy as attachingthe cable. An IEEE-488.2 interface andinternal, rechargeable lead-acid batteries areavailableasoptions.

Get agreat value.Contact your local distributor today for com­pl ete information on the new Fluke 45. Orcall toll -free 1·800·44·FLUKE, ext 33.

$635"

Dual Display

lrue-rmsvoltage andcur­rent, includingac+dc

0.02% basicdcvoltageaccu racy

0.05%basicdccurrentaccuracy

1MHzfreq uency counter

RS-232 interfacestandard·SuQoestedU,S. ListPrice

dB, with21 referenceimpedances,and audiopower calculations

Compare andRelative functions

MinMax andTouch Hold'"functions

Optional PC software forRS-232applications

OptionaI IEEE-488.2 interface,battery pack

One yearwarranty

CIRCLE 121 ON FREE INFORMATION CARD

FLUKc ®

February 1991Vol. 62 No.2

PAGE 50

PAGE 43

1::1Will.

"BEASTIE"SPEAKER

CABLESIJo\P~OVE ,YOU~ AUDIO?_/~

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50 WILL "BEASTIE" SPEAKER CABLES IMPROVE YOURAUDIO?Find out if expensive speaker cables are really worth the money.Richard A. Honeycutt

61 HOT TROUBLESHOOTING TIPSA look at the horizontal output transistor and how to use it to speedyour troubleshooting.Brian Phelps

63 1 VOLT + = ?A refresher course on standard electric quantities.Dale Nassar

55 NEGATIVE ION GENERATORExperiment with high-voltage electronics and the effects of negativeions.Anthony J. Caristi

37 TURN YOUR PC INTO A UNIVERSAL FREQUENCYCOUNTERBuild a frequency-counter/timer board that works with Windows.Joe Grasty and Bill Schulz

43 AUDIO SWEEP/MARKER GENERATORDetermine the frequency response of your amplifier or filter design.John Wannamaker

BUILD THIS

TECHNOLOGY

96 Advertising and Sales6 VIDEO NEWS 78 COMPUTER Offices

What's new in this fast- CONNECTIONS 96 Advertising Indexchanging field. Windows pains (and

12 Ask R-EDavid Lachenbruch pleasures).

20 EQUIPMENT REPORTS Jeff Holtzman 17 Letters

Data Controls Analyst 2. 87 Market Center71 HARDWARE HACKER 31 New Lit "Tl

mInexpensive visible lasers, and 81 AUDIO UPDATE OJ

22 New Products JJmore. The Boston sound: Part II. cDon Lancaster Larry Klein >

4 What's News JJ-<~

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~

ON ,.HE COVERPC's have become an essential

part of any electron ics test bench.Until recently, however, PC-basedinstrumentation was considered tobe little more than toys with theirlimited use and features. That's nottrue any longer. Take, for example,our PC10 frequency counter. It's acard that fits in an expansion slot inyour PC and operates in a Windowsenvironment. It can perform directcounts over 200 MHz, it has a 10­digit display, and a 2.4 -GHz range.Because it operates in a computer,additional features such as data log­ging are available. Turn to page 37for details.

THE MARCH ISSUEGOES ·ON SALE

FEBRUARY 1.

BUILD R-E's VIDEO TELEPHONETransmit and receive high-resolution images over standard phone lines!

B UILD A REMOTE-CONTROL A NA LYZERExamine the output of your IR remote control with this handy device.

HugoGernsback (1884·1967)founder

Larry Steck ler, EHF.CIT,editor -In-chief andpublisher

EDITORIAL DEPARTMENT

Brian C. Fenton, editor

Marc Spiwak . associate editorDaniel Goodman, technical editorKim Dunleavy,

assistant technical editor

Teri S caduto, assistant editor

Jeffr ey K. Holtzmancomp uter editor

Robert Grossblatl. circuits edi torLarry Klein , audio editor

David Lachenbruchcontr ibuting editor

Don La ncas te rcontributing editor

Richard D . Fitchcontributing editor

Kathy Teren:l:i, editorial assis tant

ART DEPARTMENTAndre DU:l:ant, art director

In j ae Lee. illustratorRussell C . Tr uelson , illustrator

PRODUCTION DEPARTMEN T

Ruby M . Yee, p roducti on directorJanice Box,

editorial prod ucti onKaren S. Tucker

adverti sing production

Marcella Amoroso

productionassistant

CIRCULATION DEPARTMENTJacqueline P. Cheeseboro

circ ulati on di rect orWendy A lanko

circulation analystTheresa Lom b ar d o

circula tion assistantM iche le Torrill~, reprint bookstore

Typography by Mates Graph ics

Cover ph oto by Diversifi ed PhotoServices

R adio-Electronics is in de xed inApplied Science & Technology Indelland Readers GUide to PeriodiCilI Liter.ature.M icrofil m & Micrpfiche editions areavailable. Co ntact ci rculati on depart­ment for detail s.

Advertising S a le s O ffices listedon p age 96.Radio-Electronics Executive and

Admin istrative Offi ces1·51 6·2 9 3·3 0 0 0.

Subsc riber Customer Servi ce:1.800·288·0652.

Order Entry for New Subscr ibers:1·800·999·7139.

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MICROWAVES: PART 4An in-depth look at solid-state microwave devices.

SEMICONDUCTOR MEMORIESTake a look at the advantages and disadvantages of CMOS, TTL, andEEPROM's.

As a service to reader s, RADIO -ELECTRONICS publis hes availab le plans or info rmatio n relati ng to newsworthy products ,techniqu es and scie nt ific and technolog ica l developm ents. Because of possible variances in the quality and condition ofmateri als and workmanship used by readers. RADIO-ELECTRO NICS discla ims any respo nsib ility for the safe and properfunct ioning of reader-buil t projects based upon or from plans or informati on publi shed in this magazine.

Sin ce some of the equipment and circuitry desc ribed in RADIO-ELECTRONICS may relate to or be covered by U.S. patents,RADIO-ELECTRONI CS discla ims any liabili ty fo r the infri ngement of such patents by the making. using . or selli ng of any suchequipment or ci rcuitry , and suggests that anyone interested in such projec ts consult a patent attor ney.

RADIO-ELECTRONICS,USSN 0033-7862) February1991.PublishedmonthlybyGemsback Publications, Inc.,500-BBl-Co unryBoulevard, Farmin gdale. NY 11735Second- Class Postage paid at Farmingdale , NY and additional mailin g off ices . Seco nd-Classmail regist rati on No. 9242 autho rized at Toronto , Canada. One-year subscript ion rate U.S.A. and possess ions $17.97. Canada$23 .97, all other countr ies $26 .97. All subscript ion orders payable in U.S.A. funds only, via internat ional postal money order orcheck drawn on a U.S.A. bank. Single cop ies $2.95 . © 1991by Gernsback Publicat ions, Inc.All rights reserved. Printed in U.S.A.

POSTMASTER: Please send address changes to RADIO-ELECTRONICS, Subscription Dept., Box 5511 5, Boulder, CO80321-5115.

A stamped self-add ressed envelope must accompany all submitted manuscripts andlor artwork or photog raphs 'if the ir return isdesired should they be rejec ted. We discla im any responsibil it y for the loss or damage of manuscri pts andlor artwork orphotog raphs while in our possess ion or otherw ise .

.e TheAuditBureau

of Circulation eo" ' ,

'"" -- .... ....

Cable TVDescrambler Article Parts

We stock the exact Parts for several articles published in Radio-Electronics

magazine on building your own Cable TV Descrambler.

February 198458-3 Type

701 Parts Pkg.....$19.00Includes all original parts.

February 1987Tri-Mode

301 Parts Pkg ......29.00Includes all original parts.

May 1990Universal

901 Parts Pkg.....$49.00Includes all

702 PC Board 7.95Original 3X4 etched, drilledand Silk-Screen pc board.

302 PC Board 7.95Original 5X8 etched, drilledand Silk-Screen pc board.

902 PC Board 9.95Improved 4X7 etched, drilledand Silk-Screened pc board.

704 AC Adaptor..... 7.9512 to 18 Volt DC @ 200ma.

304 AC Adaptor..... 7.9512 to 18 Volt DC @ 200ma.

904 AC Adaptor..... 8.9512 to 18 Volts AC @ 350ma.

701, 702 & 704..... 29.00All three for special saving .

301,302 & 304..... 39.00All three for special savings.

901, 902 & 904..... 59.00All three for special savings.

Tri-Mode Tutorial..7.9526 pages of in-depth info.

Snooper Stopper... $39.00Prevent Descrambler detection with snooperstopper/data blocker and protect your privacy.Includes free article on Cable Snooping.

Macrovision Kit...$29.00Macrovision.....now you see it, now you

don't with our macro-scrubber kit.Originally Published in Radio-Electronics.

Signal Eliminator (tunable notch filters) ••••••••••••••••$29.95Model number' & channel; #23 (channel 2 & 3) # 46FM (channel 4 to 6 & FM)#713 (channel 7 to 13) #1417 (channel 14 to 17) #1822 (channel 18 to 22)

1 remote replaces 3... A VCR in every room ..The MAC 20 wireless remotes replaces any with the first FCC approved wireless home

three combinations; TV, VCR, Cable Converter, broadcast system. 120 ft. range.Stereo, CD or other entertainment system.

MAC 20 $59.95 VC2000 $99.95

70 Channel Cable TV Converter $89.95* 6 Function Infra-Red remote.* Fine Tuning.* Memory & Recall.

* Compatible with all External Descramblers.* Channel 3 or 4 switchable output.* STD, HRC & IRC compatible.

"TlmOJJJC~JJ-<N. Attleboro, Ma. 02761

Outside USA Call 1-508-699-6935

Visa, MasterCard and COD.Add $4.00 S&H, $6.50 Outside USA.D & D Electronics, Inc. PO Box 3310,

CALL TOLL FREE 1-800-332-3557I VISA I I MC I

CIRCLE 184 ON FREE INFORMATION CARD

3

WHAT'S NEWS 'A review of the latest happenings in electronics.

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T elephone-BoothReplacement?

Advanced Co rdless Technologies(Montv ille, NJ ) began public testin gof its CT-2 technology in New YorkCity last fall. Based on two pieces ofequipment-a pocket-sized portab lepho ne and a " t e le po tnt ." low ­powered radio transmitt er-the tec h­nology offe rs an alternative to publictelephone booth s.

The cordless phones use very littl epowe r, get ting 20 hours or more fromthe rechargeable or disposable bat­teries, and are more private and lessexpens ive than cellular phones . TheCT-2 phones must be used w ithin 100yards of a telepoint.

Each telepoint , which is about thesize of the Manhatt an phone book, .connects callers to the land-line te le­phone network. From there, calls areforwarded to any location wo rldw ide ,and are reco rded for billing purposes .

A SCALE MODEL SECTION of the super­cond uct ing super co tllde r' (SSC), theworld 's larges t and mos t powerful part ic leaccelerator that is planned for opera t ionin Texas in 1998, is examined by ex­ecutives from West inghouse Electric Cor­poration. Westinghouse is competing forthe contract to man ufact ure and test morethan 8000 16.5-ton superconducti ng mag­nets that will guide thin beams of protonsaround the SSC's 54-mi le undergroundtunnel at close to the speed of light. Thecorporation, a leader in prod uc ing super­co nduct ing magnets, developed theniobium-ti tan ium alloy wire that w ill beused in the magnets. Pictured from left toright are Bruce Boswell, general managerof the collider dipole magnet divis ion;Chairman and Ch ief Executive OfficerPaul Lego ; and Dr. John Hulm, ch ief scien­tist emeritus and director of supercon­ductivity technology.

Long-life power so urc eA patented power-source tech ­

no logy deve loped by th e E.F.Johnson Company, a division of Di­versi fied Energies, Inc. (Mi nneapo lis,MN), coup les a unique light -emittingpolymer with so lar-type cells to gen­erate con t inuous, low-power elec ­tr ical energy for more than 25 years .Because the powe r is not genera tedby a chemical process, it is not adver­sely affected by extremely co ld tem­perat ures. It has bee n successfullytested at temperatures ranging from- 196°C (the temperature of liquidnitrogen) to + 100 °C (the boi lingpoint of water)

Elect ric ity is ge nerated when aphotovo ltaic ce ll is optically coup ledto a light-emitti ng po lymer. The light,generated when a phosphor mole-

FIG. 1-E.F. JOHNSON COMPANY'S long­life , low-power electrical-energy source iscreated by combining a light-emittingpolymer material (1) and a photovoltaiccell (2, 3) that has a light-collecting sur­face and a pair of electrical con tacts (4, 5).When the polymer and the photovoltaiccell are cou pled, an open-circuit voltage isgenerated between the two electrical con-tacts. .

cule is close ly coupled to a hydrogeniso tope (H-3 or tritiu m) w ithin th epolymer. Trit ium is a radioactive mate-

. rial that is currently used in a gaseo usform as the basis of light sources inwatc hes and exit lights in theaters,and that will require licensing by theNuclear Regulatory Commission . Inthe new power sou rce , the tritium ischemically bound into a solid plasticmatrix.

E.F. Johnson has achieved poweroutp uts in th e microwatt range­enough to powe r a pocke t calculatoror watc h, or to charge a capac itorthat wou ld supply per iodic surge re­quirements and then recharge- and ,expects to significant ly increase thepowe r outp ut. Whi le no end productshave been created, and commerc ialusage is several years away, potentialfuture applicat ions for the long-life,low-temperature power source couldhe in medica l implants, space , com­puters , and superconduct ivity. R-E

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39 lesson s, exams, binders and equipment. Thisspec ial introductory price includes all the benefits andassistance CIE normally extends to its students andgraduates. You 'll be entitled to unlimited access toCIE 's facul ty and staff to assist you in your studies viaa toll free 800 number six days a week , 24-hourturnaround on grading your submitted exams , CIEBookstore privileges , a patented learning method,

reference library, a student, facul tyand alumni electron ic

bulletin board and a freeissue of CIE's schoolnewspaper The Electron.All this knowledge andsupport will put you on theroad to understandingdigital electronics,microprocessing principles,computer systems, telecom-

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$

Now for the first time in CIE's 56 year history you donot have to be enrolled at CIE to receive our introduc­tory Electronic and Electricity Lesson Modules.Available for a limited time to non-students for theshockingly low price of only $99.50.

With CIE's patented AUTO-PROGRAMMEDmethod of learn ing you'll quickly learn and thenmaster the basics of electronics and electricity andthen move on to... DC/AC circu ittheories, fundamentals of bi-polarjunction trans istors (BJT), fieldeffect transistors (FET),wiring, diagram and sche­matic readings , componentidentification, solderingtechn iques... and much ,.much, more.. Your commitment to CIEends with your payment, butCIE's comm itment to yoursuccess just begins when youreceive your

• Free Issue of The Electron• Build your personal burglar alarm• Instructors available 6 days a week• 20 lesson books containing 39

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Ohio Residents add 7% Sales Tax:California Residents add 6-1/2% Sales Tax: _Total this order: _

Method of Payment: Amount Enclosed . .. $ _o Personal Check or Money Ordero Master Card 0 Visa

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5

Whats new in the fast-chang ing video industry..flllj I,' !;!H: IMI:! jill d:

COMMODORE'S CDTV interactive graph ics player is expected to cost less than $1000.

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• European HDTV setback.Europe's plan for an orderly transitionto HDTV suffered a severe blow withthe announcement that -two Britishdirect-satellite broadcasters plannedto merge. Sky Channel has beenbroadcasting in standard PAL, whi leBritish Satellite Broadcasting wasbeaming a signal in the expanded ­definition MAC (multiple analog com­ponent) system, which separates thechrominance and luminance signalsto provide a better picture. Under themerger agreement , the combinedsatellite system wi ll transmit in PALonly, after a transitional period.

BSB's MAC transmissions werepart of a plan to create a new stan­dard for direct-satellite transmission,which wou ld eventually lead to a"compatible" HDTV system-com­patible with MAC transmissions, thatis. MAC and PAL are incompatible.MAC has already lost favor in Ger­many, where broadcasters are usingLuxembourg's Astra satellite andtransmitting in PAL. At this time , onlyFrance is stil l committed to MAC. Un­der the European Eureka project. thenewall-European HDTV service, HD­MAC, was to be phased in about1992. Now everyt hing is up in the air,so to speak.

• J apan's HDTV receivers.Whi le the European HDTV systemwas to have some measure of com ­patibi lity (even if only to MAC trans­missions), Japan's Hi-Vis ion HDTV iscompatible with nothing, and will re­quire all-new TV sets, VCR's , vid ­eodisc players , and so forth . Hi­Vision is being broadcast by NHK,the government -chartered broad­caster, by satell ites. Japanese TV setmakers have now introduced the firstconsumer model Hi-Vision rece ivers ,priced generally i n the$17 ,000-$35,000 range, promisingprices could be cut in half in about ayear.

Newspaper and magazine reportsbemoan how far " behind" the UnitedStates is as compared to Europe andJapan in instituting HDTV broadcast­ing, but they neglect to mention that

the American project is far more am­bitious than the others . The U .S .plans to integrate HDTV broadcast­ing with conventional transmissions ,broadcasting from terrestrial TV sta­tions rather than instituting a com ­ple tely new incompatible satellite­transmitted service . Officia l testingof proposed American HDTV sys­tems is scheduled to start in March.

• Multimed ia . That's one of to­day's mag ic words, and no oneknows how it's going to affect thefuture of te levision, video , or comput­ing. At least three systems designedto combine video motion, audio, andinteractivity are scheduled for majorintroductions this year. CDTV, whichstands for " Commodore DynamicTotal Vision, " is scheduled for intro­duction early th is year, as an exten­sion of the Amiga computer systemin an attachment for TV sets, withsuch programs as encyclopedias ,cookbooks, atlases , and sophisti­cated video games . The hardware isscheduled to cost less than $1,000to start, with CD-ROM programs at$2 5 to $100 each. CDTV has half­screen full-motion or full-screen half­motion (15 frames per second). Thecompeting CD-I (Compact Disc Inter­active), backed by Philips and Sony,wi ll debut in the second half of th isyear, probably without full motion, buta full-motion adapter will be addedlater.

Meanwhile, Intel introduced a two­chip set to bring its Digital Video In-

teractive (DVD system to personalcomputers at a premium of less than$1,000 at the start. The DVI chipspermit interaction with full -motionvideo , as well as storage of digitalvideo on PC's. Thus it seems that theTV set moves closer to the computer,and the computer closer to the TVset.

• Digital VHS sou nd. You can'tbuy it now, but perhaps in a fewmonths there will be another featurefor VHS video recorders . At the re­cent Japan Audio Fair, both JVC andHitach i demonstrated VCR 's withdigital audio, and Matsushita (Pan­asonic) has a similar system. The newdigital sound is for Super VHS re­corders , whose expanded videobandwidth provides enough addi ­tional space for its 16-bit PCM sys­tem. The 8mm format already hasPCM audio with an 8-bit system. TheVHS group is reluctant to commer­cialize digital audio because of thedispute over digital-audio recordersand copyright protection, but there isanticipation that it will be offeredstarting this spring . The PCM audiosystem, standardized for S-VHS re­corders, uses a 48-kHz sampling fre­quency, and depth -multiplex record­ing to place the video and audiosig nals o n di fferent layers of thetape's magnetic coa ting . The twoother soundtracks (linear and helicalFM) of the VHS recordi ng standardwill be unchanged to maintain com­patibil ity. R-E

Bright KryptonBayonet-StyleLamps for Flash­lights. Use inplace of standardlamps for superbrightness . For ex­am ple , K4 re­pl aces sta nda rdPR 4. Each 79c

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, ~~!'!'~h~I!!~~~!"O",f ~P"'"electronic compone nts. Plus, we can special-order 10,000 itemsfrom our warehou se- ICs, tubes, semiconductors , phono car­tridges and styli , even SAMS~ manuals. Service is fast andthere 's no minimum order or postage charge.

.BATTERY HOTLINEl in addition to our large in-store stock , Radio Shack can now

supply almost any currently manu factu red consumer- typebattery-for cord less phones, computer memory , camcorders ,transceivers, pagers and more. No postage charge!

1991 Semiconductor ReferenceGuide. A " must" for electronics build­ing and repair. This new edition givesyou a 95,OOO-item semicond uctor sub­stitution guide plus detai led data onRadio Shack ICs, SCRs, LEOs, diodes,transistors and optoelectronics.#276-4014 3.99

BenchlPortable LCD Digital YOM.Our best mult itester! Displays trans is­tor gain directly and has diode-check,memory and cont inuity functi ons.Autoranging or manual modes. Mea­sures to 1000VDC, 750VAC, 10 ampsACIDC and resistance.#22-195 99.95

4-in -1 Soldering Tool. Operates any­where on standard butane lighter fuel.Refills in seconds . #64-2161 . . 29.95(1) 1.0 mm Tip . #64-2163 .. .. . 9.95(2) Blow Torch Tip , #64-2168, (3)Heat Blower, #64-2169, (4) HotKnife, #64-2170 available on specia iorder Each 9.95

Type Volts rnA Cat. No.K4 2.33 480 272-1169Kl 2.4 600 272-1156K2 2.4 830 272-1157K3 3.6 800 272-1158

K15 4.8 700 272-1162K12 6.0 650 272-1163K18 7.2 700 272-1164

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••Electronic Counter Module. Pre­wiredl Great for a traffi c or eventcounter. Counts up to 99,999. Ad­vanced (or reset) by external switchclosure or digital ci rcuit. Acceptscount rate up to 7 Hz. Has ' /2" liquidcrystal display. Requires " AA" bat­tery. Low current drain-only 4 IlA.With data . #277-302 16.95

Mercury Bulb Switch. Just the thingfor exper iments and alarms. Con­tacts rated 5 amps at 125VAC. Stylemay vary. #275-027 1.29

Surface-Mount Res istors. 200­piece assortment! Popular values,rated '/8watt, 5% . #271-313, Set 4.99

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(1) Precision Thermistor. Range:-50 to + 110°C. #271-110 . . . . . 1.99(2) High-Speed 12YDC Motor. Upto 15,200 RPM at no load. About 2"long (with shaft). #273-255 . . . 2.99(3) 12VDC Brushless Micro Fan.Ideal for cooling mobile equipmentand hum-sensitive circuits. 4.6 CFM.150 rnA. #273-244 17.95

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(1) Dual Mike Cable. For balancedhookups. 30 ft. #278-1281 . .. 19.95(2) Super-Flex Mik e Cable . Extra­supple . 30 ft. #278-1282 .. . . 14.95(3) 4-Conductor Double-ShieldedCable. 30 feet. #278-777 . . .. 7.95(4) Magnet Wire Assortment. 22,26, 30 gauge . #278-1345 . . . . . 4.99

Six -Outlet Power Strip With SpikeProtector. Noise fil ter, breake r.Rated 15A. #61-2780 29.95

Piezo Speaker.Only 131132" -dia.by 5/64" thin . Thish i g h- ef f ic i en c yd evi c e c a n b edriven by ICs. 500Hz to 20 kHz. 1200ohms.#273-091 . .. 2.49

(1) Min i-Clip Test Leads. 48" long.Mini test clip at one end, bana na plugat the other. Includes pin-ty~e plugadapters. #278-1160 . . . . Palr /3.99(2) Test Probes With Coiled 6-Ft.Leads . #278-750 Pair /4 .99(3) Deluxe Soft Carrying Case. Per­fect for multitesters. #22-149 ... 7.95

10-Amp Plug-InDPDT Relays.With 12VDC Coil.#275-218, 5.99With 125VAC Coil.#275-217, 5.99Relay Socket.#275-220, 1.79

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Since 1921 Radio Shack has been the place to obtain up -to-dateelectronic parts as well as quality tools, test equipment and accessor iesat low prices. Over 7000 locations to serve you-NOBODY COMPARESPricesapply at participatinu Radio Shack stores and dealers . RadJO Shack is a division of Tandy Corporation

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CIRCLE 78 ON FREE INFORMATION CARD 7

The country honors its technicians with the celebration ofNational Electronics Technicians Day.

• Consumer-Subjects coveredinclude antennas and transmis­sion lines, digital and linear cir­cu its in consu me r products , TVand VCR servicing problems an duse of test equipment.• Industrial-Subjects includetransducers , switches, powerfactor, differential amps, closed­loop feedback, b a s ic logi c cir­cu it s and functions, eleme n ts ofnumeric con trol, thyratrons, andSCR con trols.• Communications-This testcovers two-way transceiver theo­ry an d servicing, receivers, trans­mi tters, bas ic commun ication stheory, d evia tion sens i ti vi ty,quieting, an d troubleshooting.• FCC Legal-This is a 25-ques­tion op tional exam cover ing FCCregulations. Appli can ts musttake the As sociate exam , the

The CETexamTo become certified by ISCET,

one must pass both a 75-ques­tion Associate-level CET tes t, an da 75-question Journeym an-leveltest. Each multiple-choice exammust be passed with a grade of75 % or b etter. An elect ron icstechnician or student with les sthan four years of ex p er ie ncemay apply for the Associate-levelexa m, cove r ing t he followmgsubjects :

technical em ployees to be ce r­tifie d by IS CET.

• Basic Mathematics• DC Circ u its• AC Circuits• Transistors and Semiconduc-

tors• Electronic Components• Instruments• Test and Measurements• Troubleshooting and Network

AnalysisA fu lly certifi ed technic ian

must also pass one or more of theseveral Journeyman optionsavailabl e in specialized fields ofelectronics . A Journeyman ce r­tified technician must also havefou r or more years of education orexperience in electron ics . TheJourneyman options t h a t areava ilable a re :

(NEA), ISCET was founded in1970 by a com m ittee of Cert ifiedEl ectronics Technicians , whos emain purpos e was to foster re­s pect an d ad m ira t ion for theirprofess Lo n . By m aintainin gri gorous s t an d a r ds in its cer­tific ation program, ISCET is ab leto separate the highly skilled an dknowled geable technicians fromth os e with less ex per ien ce . IS­CET's main functions include di­rection an d administration of theCET program, the national ap­prentice and traintng program,the technical information train­ing an d upgrading programs ,and the serviceability inspectionprograms.

Th e CET program was de­signed to measure the degree oftheoretical knowledge and tech­nical proficiency of pra cticingtec h n ician s . A technician with aCET certificate is thought of inthe in dust ry as one who pos­sesses the train in g and expe r tisenecessary to perform th eir jobwith professional competence.Since its inception in 1965, theCET program h as become moreWidely accepted by technicians,manufacturers, and consumers.Many organizations en cou rage,and sometimes require , the ir

What is ISCET?As the proud offspring of the

National El ectronic Associa tion

I N HECOGN ITION OF ITS NEAHLY

28, 000 members , the Intern a­tional S ociety of Certified Elec­tronics Technicians (IS CET) islobbying for a joint resolution ofCongres s to d esignate March 5,1991 as National Electron icsTechnici ans Day. Congre ssmenMartin Frost and Pete Geren(Texas) have whol e-heartedlyagreed to serve as the original co­sponsors of th is bill in the House.Senate approval is also requiredfor this special legislation, an dISCET is seeking an or iginal Sen­ate sponsor for this bill.

ISCET's ch a irman, LeonardBowdre , hopes that by officiallydeclaring March 5, 1991 as Na­tional El ectronics Technici ansDay, n ationwide recognition willbe focu sed on the high standardsof performance and excellen cemaintained by professional tech­nicians. Most people underesti­mate our country 's n eed forhighly skilled a n d spe ciallytrained elec t ro n ics technicians ,who playa vital role in the elec­tronics manufacturing, testing,and s ervicing industry.

If)

gzoa:I­aw-Iw ISCET AWARDED MISSION SPECIALISTS George D. Nelson and James D. Van Hoften .6 titles of Honorary Certified Electronics Technicians for servicing and repairing the Solar~ Max satellite. Their 305·mile high 5·day service call cost $45 million, but saved the cost ofa: replacing the 5,000 pound, $300 million satellite.

8

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neering) who were awarded thetitles of Honorary Certified Elec­tronics Technicians. Figure Ishows these astronauts beinghonored by ISCET.

The astronauts we re re cog­nized by the ISCET Board of Gov­ernors for their exemplary perfor­mance in space during the peri odof April 8-12, 1984, when the So­la r Max satellite was serviced, re­paired, and returned to Earth'sorbit. They were cited for the ex­tremely difficult and delicatework required to repair the elec­tronics box for the coronagraph­polarim eter, an instrume nt thatwas not designed to be repairedin space.

Whil e worki n g ou ts ide thespace shuttle Challenger, wherethe 5 ,000 pound So lar Max wasb er thed, the astronauts u s edspecial power tools des igned forweightless conditions to repa irelectronic ins tru men ts . The sat­ellit e was res tored to operationalheal th for the first time in th reeyears, an d a dded years to itsusefu l lifetime. R-E

AliO:"4=6 : e:ksd'ei i::r'Ywh;; ~in"gpe~~.:rche~l;"o~v'rnAand MasterCard. Money orders and cashiers checksprocesse d immediately.

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Certified Electronics Technldan

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The world's farthest service callISCET not only acknowled ges

those who have successfully com­pleted their certification exam ,but those who h ave exhibitedoutstanding techn ical achieve­men t. Such is the case of MissionSpec ialists George D. Ne lson(Phd, Astronomy) and James D.Van Hoften (Phd, Hydrauli c Engt-

Don't underes timate the diffi­cu lty of the CET exam. Every yearover 6, 000 exams are taken byh opeful technicians, b ut on ly30 % of those taken pass-it's notan easy test. The best way to pre­pare for this exam is to study d ili­gently. Tab Books, In c. publi shesThe CE T Stu dy Gu ide, by SamWilson , which will help you pre­pare for both tests . ISCET alsohas a d d it ib na l s t u dy g uidesava ilable for a nomin al fee.

If you 're interested in takingthe CET exam, you ca n contactanyone of IS CET's volunteer testadministrators listed in this arti­cle for details. The exams areschedu led to be given the week ofMarc h 5 , 1991. There are manymo re test a dmi nist ratorsth roughout the country than wehav e provid ed. Thos e lis ted inthis article a re just the ones whowill be giving the exams duringthe week of March 5 . For any ad­d it ion al information you mayneed , you can contact ISCET at2708 West Be rry St. , ForthWorth, TX 76109; phone (817)92 1-9101.

Now that we have all of the for­malities out of the way, let 's take alook at h ow ISCET honored twotech n icians who have gone abovean d beyond their ca ll of duty.

LARRY STECKLER, editor-in-chief andpublisher of Radio-Electronics magazine,received this CET certificate back in 1975.

you have successfully completedthe Communications option, anadditional fee of $10.00 is alsorequired.

Co m m u n ications optio n, andthe FCC Legal exam to receive agene ral rad io-teleph one licens e.• Computer-This test coversope ration of comp uter systemswit h b as ic em phas is on h ard­ware. Subjects covered includebasic ar it h metic an d logic ope ra­tions, computer organ iza tion,input a n d output eq ui p ment,and memory and storage . So meknowledge of software and p ro­gram mi ng is requ ire d, and theab ility to explain troubleshootingp rocedures is required.• Audio-Products covered inth is option inclu de turntab les,tape decks , compact discs , a ndrad io s. The exam cons ists ofb oth digi tal an d analog sections,a mp li fie rs a n d sou n d quali ty,system set-u p, speaker in s talla­tion . and troubleshooting audiosystems.• Medical-The p r ior i ti es ofth is option are electrical safetya nd accuracy of calibration forelectromedical ins truments. Thetechn icia n mus t be familia r withbasi c vocab u lary of medical in­stru mentation , telemetry, m ea­surements , d ifferential and ope r­ational amplifier applications.• Radar- A general knowledgeof both puls e rad ar and contin u­ous radar is necessary to takethis J ou r n eyman option . Thetest covers transm itters and re­ceivers , CRT di splay systems andtheir power su pplies, anten nas ,trans mission lines a nd t hei rcharacter tsttcs,• Video-The rapidly growingfield of vide o is covere d by thisexam. The te chnic ia n needs toknow NTSC stan dards, videobasics, test signals, and the ope r­ations of both the electronics andmechan ical systems in VCR's .Also covered a re 8m m video, cam­corders, cameras and monitors,a nd the m icroprocessors used invideo products .

The fee for the CET exam is$25 .00, which includes both theAssoc ia te exam a n d a nyo neJ ourneyman option, if taken inone sitting. If the J ourneymanoption is taken separately fromthe Associate exam, each test is$25 .00. Each additional Jour­neyman option is $25.00. If youfa il any por t ion , the first retake isfree, afte r a 60- day wai tingpe r iod . The fee for any additionalretake is $ 12. 50. If you choose tota ke the FCC Legal exam after

9

ISCET CERTIFIED ADMINISTRATORS FOR THE CET EXAM

Melvin E. Talbert , CET Charles R. Schlieper, CETHeilig Meyer Service Co. Temple Jr. CollegePO Box 64189-2858 , Owen Dr. 2600 South FirstFayell eville , NC 28306-0189 Temple, TX 76504(919) 483-0801 (817) 773-9961 Exl. 255

Jacob Klein, CETNorthcentral Tech College1000 Campus Ave.Wausau, WI 54401(715) 675 -3331 Exl. 263

James C. Shambow, CETITT Tech. Insl.12720 Tech. Insl.12720 Gateway Dr. Suite 100Seallle , WA 98168(206 ) 244-3300

Duane Busby, CET2027 Sherman Ave.Mad ison, WI 53704(608) 244-0339

Preston Wallace , CET1757 Triple Crown Dr.Corpus Chr isti, TX 78417(512) 852-8022

Larry Geissler, CETIndianhead Tech. College600 N. 21st SI.Supe rior, WI 54880(715) 394-6677 Exl. 275

Jim Teeters, CET2937 E. Malden Ave.Norfolk, VA 23518(804) 428-5772

Del Dressel, CETOak land TVPO Box 110970Tacoma, WA 98411-0970(206) 840-4975

Leonard Laabs, CETWalla Walla College204 S. College Ave.Co llege Place, WA 99324(509) 527-2712

Michael Szymkewicz, CETOlymic College16th & ChesterBremerton, WA 98310(206) 478-4802

Richard K. Evans, CETPO Box 217Wilkenson, W. VA 25653(304) 752 -7267

Thomas C. Underwood, CETSony Serv ice Company3201 Premier # 100Dallas, TX 75063(214) 550-5270

Ceci l C. Poe, CET1012 McClain Dr.Sunnyvi lle, WA 98944-1270(509) 839-3995

David E. NidaNational Education Center5514 Big Tylor Rd.Cross Lanes, W. VA 25313(304) 776-6290 Exl. 24

F. Gilbert Smith, CET822 Creekridge Dr.Dallas, TX 75218(214) 348-7734

Frank Sosolik Jr.. CETT.S.T.1.Servici ng Depl.Box 4454Waco, TX 76705(817) 799-3611

Leonard M. Cowherd, CETPeidmont Tech. Ed. CenterPO Box 999CUlpeper, VA 22701(703) 825-0476

Arthur J. Ruppert, CET30217 SI. AndrewsGeorgelown , TX 78628(512) 495-1679

Rodger W. MinatraCollin County Comm . College2200 W. UniversityMcKinney, TX 75070(214) 548-683 0

J.w. (Dub) Newson, CET1310 19th SI.Lubbock, TX 79401(806) 763-8246

L.A. Leibensperger, CETLincoln Tech. Insl.5151 Tilghm an SI.Allentown, PA 18104(215)398-5300

Thom as Plant, CET29 Dean SI.Pawtucket, RI 02861(401) 723-3500 Exl. 333

Donald Haag, CETRR 3 Box 92Watertown, SO 57201(605) 886-8932

William S. Warren, CET/CSM2540 Sutherland Ave.Knoxv ille , TN 37919(615) 546-1121

Joseph H. Hudson Jr., CET1500 Yarboro ugh Dr.Sherman, TX 75090-5545(214) 892-935 6

Gene Hedgepeth, CET/CARD 4-639 E. Alberdeen Rd.Mountaintop, PA 18707(717) 868-6566

Larry Broschart, CET14124 NE Knoll SI.Portland, OR 97230(503) 255-6713

Roy W. YonceOklahoma Jr. CollegePO Box 470992Tulsa , OK 74147(918) 663-9500

Joseph Carney III, CETRadio Meter America6365 Mills Creek LaneN. Ridgeville, OH 44039(216) 871-8900 Exl. 241

A.C. Falcions , CETFalcon Electronics, Inc.3266 Kent Rd.Stow, OH 44224(216) 688-245 1

Andrew M. Flock, CETHickok Tech. Inst5100 Pearl Rd.Cleveland, OH 44129-1240(216) 351-4600

David J. Garwacki, CET4846 Oak Glen Dr.Toledo, OH 43613-3048(419) 475-9221

Robert D. Jerig, CET697 Villa AveAkron, OH 44310(216) 762-5816

J.R. Manchester, CETUniversity of AkronPO Box 61Akron, OH 44309(216) 745-0053

J-S. Glosemeye r, CETEast OK Cnty Vo Tech .4701 N. Choctaw Rd.Choctaw, OK 73020(405) 390-959 1

Linda DickinsonCraven Community CollegePO Box 952Havelock, NC 28532(919) 447-5559

Ralph V. Pollmiller, CETRalph's ElectronicsPO Box 633Jacksonville, NC 28540(919) 455-2828

Wayne Smith, CET224 SI. John SI.Arden, NC 28704(704) 255-7671

R.J. Chenoweth, CETChillicothe Area Vo Tech1200 Fair SI.Chillic othe, MO 64601(816) 646-3414

James D. Everett, CETPlall e Cnty. Avt, SchoolPO Box 1700Plall e City, MO 64079(816) 329-4646

James Blanger, CETBeltroni cs, Inc.19 Proctor Hill Rd.. Box 330Hollis, NH 03049(603) 465-2422

Carl Meyer, CET11 Hemlock Dr.West Seneca, NY 14224(716) 674-7113

Gregory J. Reiber, CETBryant & Strall on5775 South Bay Rd.Clay, NY 13041(315) 452-1105

Larry Steckler, EHF/CETRadio Electronics Magazine500 B Bi-Count y Blvd .Farmingdale, NY 11735(516) 293-3000

Hubert West, CETAdirondac k, Comm . CollegeBay RoadGlens Falls , NY 12801(518) 793-44 91 Exl. 626

John H. Spurlin , CETwayne County Comm. College8551 GreenfieldDetroit , MI 48228(313) 496-2691

Bob Bellers, CETWashtenaw Comm. College4800 E. Huron River Dr.Ann Arbor, MI 48106(313) 973 -3316

Dr. Joel Go ldberg, CET6762 Red Cedar LaneUnion Lake, MI 48085(313) 360-2 092

E. Eugene Ranta, CETMacomb Comm. College14500 Tweive Mile Rd.Warren, MI 48093(313) 445-7455

Walter E. Reilly III, CETLansing Comm. College901 Cleveland SI.Lansing , MI 48906-5 431(517) 485-9551

Willard Rush , CETOakland College3361 Aspen-6304Lake Orion , MI 48359(313) 391-2152

Earl Tickler, CETRets Tech. Tram Center1520 S. Caton Ave.Baltimore, MD 21227(301) 644-6400

Robert A. Ciufell i444 Fairmont SI.Fitchburg , MA 01420(508) 674-1000 Exl. 250

Frank Serra, CETSerra 's TV Video1686 Mass. Ave.Cambridge, MA 02138(617) 492-266 1

M.G. McCann Jr.. CETMcCann Electron ics100 Divis ion SI.Metairie, LA 70001(504) 837-7272

James R. Sorrels, CET/CSM110 Oakridge Dr.Shreveport , LA 71106-7113(318) 686-4637

Gordon L. Burgess, CETGreat Northern Paper Co.E. Mill inockel. ME 04430(207) 769- 9912 Exl. 1300

Stanley Creitz, CETNCK Area Vo Tech . David Lewicki, CETPO Box 507, West Campu s Dr. 9830-26th Ave.Beloit, KS 67420 Plymouth , MN 55441(913) 738- 2279 (612) 627-2778 Exl. 5210

Edward J. Kimmel, CET2061 Eastern ParkwayLouisvill e, KY 40204(502) 451-3457Test Day Feb. 24th

Lamarr W. Ritchie , CETHazard State Vo-Tech School101 Vo-TechHazard , KY 41702(606) 436-3101

W.H. Hartzf eldt, CETDelta-Ouachita Vo Tech.609 Voc ational Pkwy.W. Monroe, LA 71291(318) 396-7431

Steven B. Lumpkin, CET164 Acadian Dr.Lafayelle, LA 70503(318) 233-6942

Keith E. Knos, CETKnos Electronics1206 Elm Blvd.Liberal , KS 67901(316) 624- 5908

Paul K. Tan, CET915 Augusta SI.Oak Park, IL 60302-1678(312) 848-6327

Paul R. Towbridgelnst, of New Cinema Artists407 E. 25th St.. 6th FloorChicago , IL 60616(312) 225-3400

Frank Teskey, CETF.J. Teskey Enterprises3094 Lafayell e Rd.Indianapolis, IN 46222(317) 926-2639

Leonard E. Bawdre, CET125 SE Tho rnton Ave.De Moine s, IA 50315(515) 964-6484

Gerald P. Breitb ach, CETKDTH Radio Station8th & Bluff SI.Dubuque, IA 52001(319) 588-5694

Michael L. Baughm an, CETKS City Area Vo Tech2220 N. 59th SI.Kansas City, KS 66104(913) 334-1000

Daniel B. Mundy, CETNorman's Electronics3653 Clairmonnl Rd. NEAllanta , GA 30341(404) 451-5057

James Peek, CETPanasonic4245 E. International Blvd.Norcross , GA 30093(404) 717-6858

Joe T. Reese, CETReese Elect . Inc, Box 499129 South Green SI.Swainsboro , GA 30401(912) 237-7010

W.R. Rooks, CETShiloh Rd. Rt 6Box 181Americus, GA 31709(912) 928-028 3

James P. Van Sant , CETPickens Tech.240 Burnt MI. Rd.Jasper, GA 30143(404) 692-3 411

James D. Hite, CETPinellas Vo-Tech6100 1541hAve. NClearwater, FL 34620(813) 531-3531

Karl A. Hunter, CETFL Comm. Colleg e2007 Catlin Dr.Jacksonvill e, FL 32211(904) 744-8480

Perry "Jim" Parks, CET/CANu-Pro Service1055 Hwy 434Winter Springs , FL 32708(305) 699-8811

Noel ShevackNew England Inst of Tech.1126 53rd CI.Palm Beach, FL 33407(305) 842-8324

Dennis P. Abell , CET3433 Royal Oak DrTitusville, FL 32780(305) 269-4208

Edward Guar y Jr., CETEddy's Radio & TV Service1110NE 4th AveFI. Lauderdale , FL 33304(305) 463·2998

Douglas E. Minter, CETAmer. College of Tech .102 N. CenterBloomington, IL 61701(309) 828-5151

FA Schwarzkopf, CET/CATriton College Rm T-2012000 Fifth Ave.River Grove, IL 60171(312) 767-4126

William J. Neilsen404 S. MainMoscow , 10 83843(208) 882 -2123

Art Sorensen, CET1416 N. Lincoln Ave.Loveland , CO 80538(303) 669-0883

John F. Stackhouse, CETITT2121 South BlackhawkAurora, CO 80014(303) 695-1913

Anthony R. Valdez, CET1919 Rolling Hills Rd.Cortex, CO 81321(303) 565-8457

John E. DePalma, CETCT School of Electronics586 Ella Grasso Blvd.New Haven, CT 06519(203) 624-2121

Silvino AlonsoCA Business lnst,3550 John son Ave.EI Monte, CA 91731(818) 444-7779

Howard Bardach, CETThe Audi o Specialist4381 Tujunga AVG.Studio City, CA 91604(818) 763-3009

C.S.E.A.Tambra Oberlander13666 S. Hawthorne #3Hawthorn e, CA 90250(213) 679-9186

John V. Craig , CETOxnard College4000 S. Rose Ave.Oxnard, CA 93033(805) 986- 5807

Anthony J. HaagPO Box 27264Concord, CA 94527-0264(415) 682-9010

David Marson , CETGolden State School3916 S. ChesterBakersfield, CA 93307(805) 833-0123

Fred Potter, CETAmeritech College6843 Lennox Ave.Van Nuys, CA 91405-4043(818) 901-7311

T. Van Iderstine, CETSouthwest State Tech College925 Dauphin Island PkwyMobile, AL 36605(205) 947 -4441

Jim GormanEastern AZ Co llege600 Church SI.Thatcher, AZ 85552(602) 428-1133

Frank Grabiec, CETDyna-tron ics1704 E. ClaremontPhoen ix, AZ 85016(602) 279-4176

H.J. Paine, CET4631 E. 8th SI.Tucson, AZ 85711(602) 881-6784

Kevin J. Price , CETN.E.C.825 E. Hospitality Ln.San Bernardi no, CA 92408(714) 885-3896

Lynn ReynoldsWoodruff Region Occup.Cntr. 302 W. WeberStockton, CA 95203(209) 944 -4612

Frederick J. Smith , CETEd. DeptlCA Mens ColonyPO Box 8101San Luis Obispo , CA 93409(805) 772-2009

Jon R. Sturt z, CET10840 Alandal e wayRancho Cordova, CA 95670(916) 635-6000

Donald Surelle, CET2728 Panay CI.Carmichael, CA 95608(916) 487-6959

Charles Fell ers, CETMesa State CollegePO Box 2647Grand Junction, CO 81502(303) 242-9307

Rick PageTechni cal Trades Insl.2315 E. Pikes Peak Ave.Colorado Springs, CO 80909(719) 632-7626

(f)oZoa:I­oW-lWoCi«a:

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FIG.1-THE LM1881 SYNC SEPARATOR,made by National Semiconductor, requires very \few components to make it work.

ator, I have to be able to identi­fy the sync on the incomingvideo. Any ideas?-C. Bald­win, Bangcock, Thailand

Fortunately for you , what you'retryi ng to do is fairly common. Whileit's possible to des ign your own syncsepara tor, it wou ld be a lot of un­necessary work because there arechips around that can do the job foryou.

Remember that stripping sync issometh ing that's done in every TV seton the market and, as a result, semi­co nductor manufacturers havejumped into the market with single­chip solutions to the problem. Sev­eral com panies make them, but theone I usually use is the LM1881 madeby Na tiona l Semiconductor. I 'vefound it very easy to put in a circuitand fairly tolerant of variations in synclevels and signal voltage s.

The pinouts of the chip are shownin Fig. 1 and I've also drawn in thecomponents needed to make it work.As you can see, all it takes is twocapac itors and one resistor. Nothingcou ld be simpler but you still shouldwrite to National Semiconductor toget a data sheet for the IC (NationalSemiconductor Corporation , 2900Semiconductor Dr ive, Santa Clara,CA 95052-809 0),

W hen you contact t he m, youshould ask where you can get the partsince I don 't know what the avail­ability is like in your part of the world .You might find it easier to deal with asupplier in the United States but, nomatter what you do, it's not a com­mon IC so you 're going to have to dosome investigating if you want to buyonly one or two of them . Minimumorders can be murder.

8ICOMPOSITE. 0---"'-1OUT

V/D £ O /N o-J / 2 ...7:....- -0 O D D / EVE N OUT

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VIDEO SYNCI'm building a video circuit

and want to get the sync sig­nals from a standard com­posite video input. My ultimategoal is to be able to mix videosignals together and, eventhough I have a good designfor the mixer and sync gener-

est the video connector), and windsup at slot #1 (the one nearest thepowe r supply), As soo n as the Ap plefinds a disk contro ller card, it turnscontrol over to the firmware locatedon the card . W hat's important to real­ize is that the com puter will recognizethe first controller card it finds. If youhave one in slot # 6, it won't pay anyatten t ion (at boo tup) to any others inlower numbered slots .

If you want to boot off the Sider,you have to put its controller card in ahigher numbered slot than the oneused for the regular disk drives . Sincethe disk contro ller is usually locatedin slot #6, the Sider 's contro ller cardshould be in slot # 7. As an alter­native, you can access the Sider bytyping PR# X' at the App le promp t(the "X" is the number of the slot inwhich you 've put the Sider's control­ler card).

W hichever method you choose,accessing the Sider shou ld turn on itsactivi ty light and whatever boot pro­gram is on the disk should show upon your screen . Both DOS and Pro­DOS (the two main operating sys­tems for the App le series ofcom puters) have to be patc hed towork with the Sider and the only wayto do that is by using the sof twa rethat was originally supplied with thedrive .

12

APPLE DISKI have an Apple lie and was

recently given a hard-disk sys­tem to use with it. I was toldthat the disk had already beenformatted but I haven't beenable to get it to work in mycomputer. Even though I havethe interface card plugged intoone of the slots, I can't seem toget the hard disk to respond.The manufacturer of the driveis the First Class Company.Can you help me with thisproblem?-B. Fischer, Indi­anapolis, IN

The company you're looking for isca lled First Cl ass Peripherals and ,the last time I dealt with them , theywere located in Carson City, Nevadaand th eir pho ne number was 800538-1307. It's been a while since I hadanyt hing to do with them but, as Iremem ber, t hey were always ex­tremely helpful.

Your best bet is to get in touch withthe m and get the software and man­uals that we re supposed to accom­pany the drive. If you can't do that,check with a local Apple user's groupand see if anyone can help you there .The Sider (the name for their drives),was one of the first hard disks avail­able for the Appl e II ser ies of compu t­ers and I have no doubt that they solda lot of them.

There are a few things you can tryto make sure the drive is still working .You said that yo u had the cardplugged into th e co mp uter, butthere's a good chance you're not is­suing the proper comma nds to ac­cess it. When the Apple is first turnedon , it checks the slots to try and find adisk controller card . Each slot has256 bytes of memory in the main Ap­ple memory map, and each card isdes igned to wo rk in a slot that has a

8 particu lar signature that indicates itsz funct ion . By examining these sig­~ nature bytes , the Apple is able toG identify the cards connected to it.~ At powerup, the Apple wants to6 find a disk control ler card and it scanso throug h the slots looking for one . TheC2 scan starts at slot # 7 (the one near-

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onds. That is the rate at which thelight wi ll change and, even though it'sa bit fast for a real traffi c light , itshould make for a more interest ingdisplay in your driveway.

The clock pulses from th e 555drive a 4017 whose outputs controlrelays that turn on each of the trafficlights in turn . The reason I'm using a4017 here is that it can control 10relays and I don't know how many youhave in your traffic light. A ll you haveto do to add more lights is add morerelays and move the reset connectionon the 4017 .

I think your idea is great and Iwo uldhave done exactly the same thing if Ihad managed toget my hands on oneof those traffic lights.

WORD/HOME PROCESSORAt a recent garage sale , I

purchased a word processormade by an outfi t i n Sun­nyvale, California called Sys­tel. Although the only I/O portis the keyboard connector, I in­tend to use it as the basis for ahome monitor/control system.The system is based around aZ-80A but I don' t have anyDOS software that will w orkwith it. Do you have a ny su g­gestions?-G. Farr Jr., GardenCity, K S

I have seve ral suggest ions, butthey all add up to the same thing, andI'm afraid that none of them are whatyou're looking for. Trying to build orconvert a computer to a home con-

continued on page 80

FIG. 2-YOU CAN CONTROL a traffic light, or any other similar device, using this circuit.An AC-powered battery eliminator can be installed right inside the light, along with thecircuit itself. . -r-

TRAFF IC LIGHTI have an old traffic light and

want to get it working and useit as a yard light in my driv­eway. What I need is some wayto control the AC and make itwork like a real traffic light.There must be some simpleway to do this.-A. Haycock,Corvallis, MT

Before we get started on yourprob lem, let me tell you that I th ink it'sa great idea. As a matter of fact, ifthere are any of those lights left, I'd.like to find out where I can get one formyself.

I'm not sure how you want the thingto operate and you haven 't to ld mehow many lights you have to control.Traff ic lights can have one , two, three,or more individual lights. Wh ateverthe case , there are several ways youcan get the thing working.

I'm gue ssing that you wa nt thelight s to cycle back and forth and,since I can't imagine that there 's thatmuch traffic in your driveway, abso­lute accuracy in timing isn't really allthat criti cal.

One simple way to control the lightis shown in Fig. 2. A ll you need is ahandfu l of part s and the layout isn't atall crit ical. You can build the circuit ona piece of perforated co nstruc t ionboard and put it inside the light itself.You' ll have to put a power supply inthere as well but the circuit draws solitt le power that you can use an AC­powered batt ery eliminato r.

The 555 is set up as a timer with anoutput frequency of about 10 sec-

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ference , which required further band­wid th reduc t ions . That' s what hap­pened to th e so und of AM radio .Throu ghout th at time, of course,man-made interference was also onthe rise.

Many people suspect that the radi­os in the ir old cars sounded better­and they did . Today it's hard to findAM radios with decent bandwidth . Ipossess a few, and have amazedmany friend s who thought they we relistening to FM. The sound of manyAM stations is very good, if you canfind something suitable on wh ich tolisten.GEORGE THOMASChief Engineer, WJDX/WMSIJackson, MS

SATELLITE TV PROGRAMMINGIn his art icle "The Chang ing Face

of Sat el li t e TV " CR a d i o -E l e c ­tronics , November 1990), RobertAngus did a good job of describingthe tip of the icebe rg, but he eitherignored or was unaware of the mostimporta nt part-what you can no tsee . He also short -changed the exist­ing home recepti on of satellite re­transmitted signals that include net ­wo rk te levision, cable programming ,audio data, narrowcasts, and a vari­ety of excellent educational program­min g . EXist ing sa te lli te ca pac itymakes available more than 500, not200 , channels . Less than 20 % ofthose channels carry " cable pro­gramming to viewers ."

Mr. Angus and others hype the po­tential for smaller reflectors. Phased­array pane ls have been used foryears by the military. The size of re­flectors and phased arrays that arecapab le of supp lying sufficient signallevels is shrink ing because of ad­vances in HEMT technology. Size isalso inf luenced by geographic loca­tion, sources of interference, obsta­cles , weather, equipment used-and,yes , TWT CTraveling Wave Tube) out­put powe r. With every reduct ion insize co mes other t rade-off s . Theproblem of non-compatible encryp­tion-decryption technologies, whichMr. Angus so correct ly addresse d, is

STILL MORE ON AM RADIOI read w ith inte rest the letter from

Matthew Bailey C'More on AM Ra­dio") that appeared in the Decemberissue of Radio-Electronics. Hestated that in the beginning many AMstat io ns used standard telephon elines with 5-kHz upper limits for stu­dio-to-transmitter links. I can 't com­ment on that , but his next sentencesaid that AM radios were built w ithnarrow bandwidth IF filters to mini­mize interference .

What interference? In the begin­ning, there we re not many commer­cial power lines or much elect ricalequipment to gene rate interference.There certainly weren't enough sta­t ions on the air to interfere with eachother.

In fact, radios did not have narrowIF's. M any sounded grea t-oncetechno logy produced better speak­ers , of course. Some units had selec ­table bandwidth that used a swi tchlabeled "Voice-M usic." I believe themain reason for that was to allow formore intelligible speech.

In the sixties, some radio program­mer dec ided that the loudest stat ionin a market would have the most lis­teners. That started a new trend thatcaused sta t io ns to use grea te ramounts of audio processing (com­pression , limiting, and cl ipping), Be­fore that, most stat ions used modestamounts of compress ion CAGO tocounteract operato r gai n-ridi ng er­rors . Limiting was used to preventovermodulation by loud peaks.

W hen stations used more pro­cess ing, the average progra m-mate­rial leve l increased great ly. Thatcaused the occupied bandwidth ofstat ions to increase in density as we ll.Now there was real interference.

Man ufacturers gradual ly began toreduce the bandwidth of receivers toreduce the interference . The pro­gra mmers noticed that treb le waslack ing and began to use pre-empha­sis to get the sparkle back in theirsound.

The more that receiver bandwidthwas cut, the more trebl e boost wasnecessary, which caused more inter-

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NTSC-TO-RGB CONVERTERSeveral incorrect statements ap­

peared in Jim Harrigfeld's art ic le" Build an NTSC-to-RGB Converter"(Ra d i o -El ect r o n i c s , O ct ober199m. The subheading says , " Put aTV in your VG A monitor," and thetext says that standard NTSC videorate requ ire ments elim inate " mostfixed-freq uency (digital) monit ors­i.e. , mos t CGA and EGA types."

Both statements are false. As areference, I cite the Ask R-E columnon page 12 of the same issue. Todisplay a standard NTSC signal, a15.75-kHz horizontal scanning rate isrequired. The table on page 12 showsthat VGA does not use that rate ,while CGA uses exactly that rate . Infact, CGA video was originally de­signed so that PC users could useth ei r colo r TV se ts as mon it ors .Please take care to make your art i­cles technically correct !

I a lso agree with Mr. Burton("Throwing Cauti on to th e Wind, "Letters , October 1990) that caut ionsabo ut handli ng CMOS see m over­done. The first CMOS chips wereindeed static sensitive, but manufac­turers quickly added input-protectiondiodes.EARL MORRISMidland, MI

Both of the statements in whichMr. Morris finds fault appeared as aresult of editing errors. The subhead,of course , should have read "Put a TVin yo ur M ultisync M onitor. " The tex tthat Mr. Morris quotes is not as clearas it should be. The po int we tried tomake is th at there are tworequirem ents for a monitor: 0) that itaccept analog inputs. and (2) that itbe capable of scanning at 60 Hz ver­tical and 15. 75 kHz horizontal. A l­th ough a C GA monitor s ca nsadequately, it generally has only dig-

sions mailed out by PSpice or IsSp­ice . There is also a student version fordigita l circuits called Micro-Logic II. Italso costs about $50.

I just grad uated from an electricalengineering program and I used bothof those software packages exten­sive ly, wi t h exce llent results. Bothbook/softwa re packages are avail­able from Addison-Wesley PublishingCompa ny ( IS BN 0-201-50 552- 5 :Micro-Logic II; ISBN 0-201-50542-8 :Micro-CAP II).DONALD HAROOTUNIANWebster; TX

SPICE VARIETYI just fin ished reading T.J. Byers'

article about SPICE in the Novemberiss ue of Radio-Electronics, inwhich he mentioned PSpice and Is­Spice. I'd like to mention ano therproduct, called Micro-CAP II, which isa student vers ion of the orig inalMicro-CAP. It has all the capabilitiesof the origin al exce pt that it is set upfor only 25 nodes instead of 150nodes. The student vers ion has avast built-in library for such com po­nents as op-arnps, tra nsforme rs ,NPN an d PNP tran si sto rs , MOStransistors, diodes. and more. It alsoincludes a schematic editor, net list ,bo de pl o ts, t im e-do main plo t s ,Fourier analysis, and more . The stu­dent version costs less than $50.00and comes with a manual writt en forthe non-professional. I found that tobe much better than the sample ver-

a hurdle, not an impasse. VLSI cir­cuits will soon permi t multip le digital­and analog-signaI-processing and de­crypti on equ ipme nt all wi thin thesame receiver and/or the te levisionitse lf. But all of this technical informa­tion is just the tip of the iceberg!

The articl e stated, " S ince thesame pool of feature films should beavailable to all the PPV hopeful s, andthe majors promise to offer basic pro­gramming co mpara ble to currentbasic cable ..." That's where the restof the story begins. Most exist ing"cable" prog ramming is controlled byvery few MSO's or Multiple SystemOperators (giant cable companies),and/or by product ion companies thateither own or are owned by MSO's.Those giants co nt rol programmingand, more imp ortant , th e majo rsources of programming. Since thenetworks want to be carried on cablein favorable channel spots (2-13),they are not a source of com pet it iveprogramming.

Without prog ramming, the asser­tion "Satellite television received onsmall, flat antenna panels, promisesto give cable TV a run for the money"ignores reality. Congress and many ofus in the industry have wres tled withprogram-acce ss problems for morethan fou r years . Without program­ming , any techn ology that is no towned or at least controlled by cableinterests wi ll wither and die on thevine !ROBIN ADAIRColumbia, KY

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ital inputs and thus will not work. A nEGA not only scans at the wrong fre­quency but it also has digital inputs.A nd a VGA monito r. although it hasanalog inputs, will not scan at thecorrect rate. That 's the reason for ourrecomm endation for multi-frequency­type monitors.-JIM HARRIGFELD

BRAIN POWERWhil e I was not surprised that there

were obje ctions to Don Lancaste r'sclaim of a four-b illion-bit human braincapaci ty (Hardware Hacker, Radio­Electronics, January 199m, I wasdisappointed in the nature of the ob­je ctions (Letters, May and November199m , given the recent popularity ofneural network research . While it istrue that the brain compresses dat a,it is also true that the compres sionalgorithms are part of the brain and(theo ret ically) could be mimicked bya computer. The real issue is that the"prog ram " of the human brain is nottotally contained in its four-billion neu­rons. It is the ten thousand (roughavera ge) interconnection s to eachne uron that determine the " pro ­gram." I'm not sure how much reso lu­tion the analog connection st rengthshave , bu t I' ll g ue s s about 3 -bitswo rt h. Therefore , to mimic the brain,you would need and as soc iat ivememory structure with a capacity ofabo u t(23)( 4 x 109)(1 x j 0 4 ) = 3.2 x 10 14

bits. Keep in mind that many of thebrain's functions have been efficiently" hard-w ired " over a billion years ofevolutions to avoid the waste of con­nections during trial-and-error pro­gramming. We are still a long wayfrom const ruct ing anything with thecomplexity and power of the humanbrain.GEORGE LEGTERSMelbourne Beach. FL

plac ed over many tou ch contro ls .When used over a tou ch-control pan­el on a unit that has an audible signalwhen buttons are pressed , the beepand the Braille might be enough toprov ide re liable o pera tion by thesigh t less .

As for a clock radio, perhaps heco uld use a separat e cl ock t hatchimes at the hour and each quarterhour. He could inte rface it with a radioto turn the radio on at the appropriatetime. If that didn't work , maybe a ta lk­ing clock would be eas ier to use.

Mark V Electronics (8019 E. S lausonAve ., M ontebello , CA 90640) offe rstwo such mo dels.

One ot her possible source of infor­mati on is an orga nizat ion call edChristian Record Brai lle (P.O . Box6097 , Li nc o ln, N E 68506). Theymake audio/visual products for thebl ind. M ost of their products areCh risti an st udy and information ma­ter ials , but they migh t offer gu idancein oth er areas as wel l.ROGER DOERINGCamp Verde. CA 86322 R-E

CONSUMER ELECTRONICS FORTHE BLIND

In response to David Plumlee's let ­ter regarding electron ic applianc esfor the blind (Radio-Electronics,November 199m, unless productswith suc h features find w idespreadaccep tance among the sighted, it'snot very likely that they 'll appear onthe market. However, I would thinkthat he could ret rofit some app lianceshimself, or have it done for very littleco s t. " Dymo " label -making ma­chines include a model that producesBraille-character labels that can be

New B&K-PRECISION'Parfs Tester checks capacitors,resistors, transistors, diodes, SCRs, LEOs and more.There'sno need to guess oboutcomponentswith • Tests capacitance fromO.lpFto 20mF inB8.K-PRECISION's815 Ports Tester. It occurately capacitors, cables, switches; other components.measures the mast-used componentsonddisplays • Tests resistance from0.1 oh mto 20 megohms .their values an a lorge 0.8" LCD readout. Rugged • Tests SCRs, diodes and LEDs.designand tilt stand make it we ll suited for field • Tests transistor gain and leakage.or bench. • Tests batte ries under true load conditions.One look at this quolity instrument will convince • 26 measurement ranges.you the B8.K-PRECISION815 is the best buy. For • 5 foot drop-resistant case.detailedspecifications or immediatedelivery, • Tilt stand for bench use.contact your loca l distributor. • Includes test leads

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Data Controls Analyst 2 Data line Monitor

W e've all had the experienceof trying to troubleshoot aPC's serial data line to es­

tablish reliable co mmunicatio ns be­twee n a PC and exte rnal device suchas a modem, pr inter, or serial-to -par­allel converter. It's usually a diffi cultjob because you can't see what's go­ing on. Sure , you can use breakoutboxes with LED indicators to t ry toget the lines matched up co rrect ly,but if the com municatio ns prob lem iscaused by an incorrect trans missionrate, glitc hes on signal lines, or anun re i iabl e data -com municati on schannel, simple tools just won 't dothe job . That's w hen you need a de­vice like the A nalyst 2 dat a-linemonitor and digital test set from DataCo ntro ls (2183 Buckin gham Road,Suite 217, Richardson, TX 750 8H

The A nalyst 2 is a handheld unit ,but w i t h a s ize o f abou t4Y4 x 8Y4x 1% inches, you' ll proba­bl y p refer t o leave it o n yo urbenchtop. A wa ll transformer pro­vides powe r to the bottom of the unitthrough a detachable cable. The frontpanel features 8 functi on keys , a 2­line by 32 -c harac te r backlit LCDreado ut , and e ight tri-co lo r LED 'sacross the top of the unit.

O n power- up th e A na lys t 2performs a self test, afte r wh ich it'sready to test data lines. The mainmenu of 'the unit con ta ins twelvechoices for the appropriate mode ofoperat ion. Each mode is displ ayedone at a time, and the list is scro lledthro ugh usi ng up or down curso rkeys .

Operating modesIn th e Data Monitor mode , th e

A nalys t 2 can captu re and disp layRS-232 ser ia l d at a st reams .Asynchro nous , synchro no us, or auser-defi ned bit-oriented protocol are

~ supported , and the disp lay can be in az characte r-oriented for mat or in hex­~ adecim al. To aid in tro ubleshoot ing,t) the Ana lys t 2 can be triggered to start~ reco rding w hen it sees a spec if icw6 group of characters . Sub menus leto you select the proper signal clocking,C'f data format, how the data is sto red in

20

CIRCLE 10 ON FREE INFORMATION CARD

Troubleshoot, test, andanalyze data circuits quickly.

the capture buffer, whether spec ificsignal transitions are captured, andhow the display should show the cap­tured data.

The Review Data mode provides away to examine and manipulate thedata sto red in the non-volatile capturebuffer. As in the mon itor mode , vari­ous sub menus are used to selectdata formats.

The Distortion mode is used to de­tect the deviation of a signal's actualti mi ng pa ra me te rs f rom wha t itshould theoretically be. Three typesof distortion, gross, isochronous, andbias, can be measured.

In th e Tim e De lay mode , th eA nalyst 2 meas ures a device 's re­spo nse delay. It sends out contro l sig­nals, and waits for respo nses . Forexample, the length of time betweena request-to-send CATS ) and the co r­responding c1ear-to-send (CTS) canbe measured.

The Analyst 2 can also act as asource of data in its Simulate mode,where it outputs data to verify that adata channel is working properly. Itcan also be used to test printers,mod em s, t ermin als, and th e li ke .Wh en requested the unit will output,in either ASCII or EBCDIC coding aQBF or quick-brow n-fox message,which contains every letter of the al­phabet, the numbers 0 throu gh 9, acarriage return , and a line feed. Asyou might expect, data-framing and ­format modes are selectable.

To simulate a loopback device, theAnalyst 2 can be run in it s Echomode. When running, the unit dig­itally loops back all data present ed onpin 3 (rece ive data) onto pin 2 (trans­mit data),

A bit-error rate test or BERT is pro­vided to determin e the perform ancelevel of a data-commun ications line,and whether it can support communi­cations w ith an acce ptable number ofbit errors. Exce ssive line noi se ,cross talk, and random burst errorson the line can be detected . A block­error rate test or BLERT is similar to aBERT, except that it spec ifically teststhe capability of a data-communica­tions line to handle blocks of mes­sages of spec ific length . Another testmode-CERT or character-error ratetest-is very similar to the BLERTmode, exce pt that the block size isdetermined by the bits-per-characterselect ion. A final rate -test mode­erro r seconds test-is used to deter- 'mine the performance of a data lineover time.

We found that puttin g the A nalys t 2to work was not too difficult-oncewe got the hang of it. Unfortunately,the operating manual supplied withthe unit was diffi cult to decipher inmany cases . For example, we were atfirst confused about the proper wayto select the right choices from themenu. We did figure it out, but with­out help from the manual. A ll thingsconsidered, that's a minor com plaint.We think that the $965. Analys t 2data-line monitor is certainly worth alook from data-communications pro­fessionals. R-E

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Add trecuency-mooearem entcapabmties to your workbenchwith this inexpensive counter.

In " Build Th is BenchtopFreq uency Cou nte r," (De­cember 1990) we were un­able to provide the PC-boardfoi l patterns . They are re­produced here.

We greatly exaggeratedthe capabilities of th e cou n­ter. Because of the compo­nents used , the cou ntercannot perform at f requen­cies above 25 MHz. We'resorry for any confus ion ourmisstatements caused.

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Train at Home to be anElectronics Technician!

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o IBM-Comp atiblePersonal Computer

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Peoples College introduces some training firststo make your learning experience morecomplete:

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oin dustry Certification Tra ining Guide ­provided with three of our programs .Gives you first-hand insight into theexamination you may take for yourprofessional license .

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Professional training and equip me nt ca n helpyou qualify for a dynamic, high-paying ca reerin your spa re tim e.

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NEWPRUse the Free Information Card for more details on these products.

CIRCLE16 O N FREE IN FO RM ATIO N CARD

see the effec ts of shorten­ing or lengthening the di­pole. The user can instantlycheck multi-band dip olesand trap vert icals to see ifthe low SWR point s are po­sit ioned co rrect ly, and ad­just the anten na until theyare rig ht . The M FJ -207helps locate the best placeon a car to mount a mobileantenna. In addition, it canbe used to observe th eeffec ts of rain or snow onthe beam or dipole, tune up

CIRCLE 18 O N FREEIN FORM ATION CARD

HF SWR ANA LYZER.Providing a complete pic­tu re of an ante nna SWRover an ent ire band-with­out a trans mitte r, SWRmeter, or any other equip­ment- th e MFJ-20 7 HFSWR ana lyze r makes iteasy to se t up and pre­cisely tr im an antenna. It isused by plugging the an­te nna into the coax co n­nector, sett ing the analyzerto th e desired frequ ency,and reading the SWR. Thebatte ry-o pe rate d, hand ­held unit can be brought toth e an te nna to directl ymeasure its SWR withoutthe distortin g effec ts of thecoax. SWR changes canbe monitored while adjust­ments are being made, andthe user can immediately

ion production and ensuresproper balance. A variablespeed con tro l adjusts threefans that move the ions to­ward the work surface .

The A60420 overheadionizer cos ts $630.-De­sco Industries, Inc. , 761Penarth Ave nue , Wa lnut,CA 9 1789; Tel :7 14-5 9 8 - 2 7 5 3 ; Fa x:714-595- 7028.

Th e Co re ModulelXTranges in price (to OEM 's)from below $ 100 in quan­titi es of 10,000 and up to$ 130 for quant it ies of 1000.A Co re Mo dulelXT D e­velopment Kit that includes't h e Core Mod ulelXT,MiniModulelFSS, Mini ­Modulel VGA, all cables,mo unt ing hardware , man­uals, and DR DOS costs$ 100 in quantiti es of 100 .Th e MiniMo dulel SSDcos ts $9 0 in 100's. ­Ampro Computers,Inc. . 990 A lmanor Avenue,Sunnyvale, CA 94086; Tel:408 - 522-2 100 ; Fa x:408- 720 -1305 .

CIRCLE 17 O N FREEINFO RMATION CARD

tional utility programs auto­mati c all y co nve rts anydisk-based PC softwa re toSSD operation.

The MiniModule expan­sion board s, w hic h stackover o r und er th e C o r­eModule , add co nfigura ­tion flexibility, allowing theadd iti o n of C GA, EGA ,V G A, LCD, and e lec ­t rolurnm escent flat -panelco nt ro lle rs ; a 24 00 -bpsmodem; a LAN interface;and other capabilit ies . TheMiniModulelFSS providesfloppy dr ive, SCSI, and se­rial port contro llers in oneextreme ly co mpac t pack­age.

tained. A built-in alarm cir­cuit continuously monit ors

PALM-SIZED CPU MOD­ULES. Meas uring o nly3 .6 x 3 .8 x 0 .6 in ch e s ,Ampro 5 CoreModules arefully co nfigu red PC-com ­patible C PU modules withmemory, so lid-sta te disk ,ser ia l and parall el I/Oports, real-time clock, andkeyboa rd and speaker in­terfaces. Th e Co reMo d­ulel XTCpictured) was intro­duced in lat e 1990 ; th eCore Mo dulel286 andCo reModulel386 sho uldbe availab le in 1991. De­signed for embe dded ap­pl ica t io ns, each modulecan be used alone as acom ponent -like, PC- com ­pat ible engine, or 'can beco mb ine d w it h A mprosMiniModule expa nsion pe­ripherals to build completesys tems .

The CoreModulel XT isequipped w ith a CMOS­enhance d 8088-compat i­ble mi croprocessor th atoperates at 9.82 MHz, anda full co mplement of PC­co mpa t ib le D M A co ntro l­lers, interrupt co ntro llers ,and timers. It co mes withtwo byt e-wid e sockets forEPROM , f las h EPRO M ,stat ic RAM , or NOVRAMmemory that can be usedas bootable, D OS- com- .pa t ib le so lid-s ta te di sk(S S D), e l i m ina t ing th eneed for floppy drives. Op-

OVERHEAD IONIZER. Toneut ralize sta t ic chargeson the wo rkbe nch withouttak ing up be nc h space ,Descoe model A 60420ionizer mou nts overheadand plugs into a standardAC out let. The ionizer of­fers an automatic shut ­down feat ure that turn s theunit off if proper ioni zingconditions cannot be main-

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Discover Your Career Potential In TheFast Growing Field Of High-Tech Electronics!

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Practical Training...AtYour Own Pace.

Through CI E, you can train for yournew career while you keep your pres­ent job. Each course allows a gener­ous completion time, and thereareno limitationson how fast you canstudy. Shouldyoualready havesomeelectronics experience, CIE offersseveral courses which start at theintennediate level.

"State-Of-The-Art"Facilities & Equipment.In 1969, CIE pioneered the first elec­

tronics laboratorycourse, and in 1984,thefirst Microprocessor Laboratory.Today, noother homestudy school canmatch CI E's state-of-the-art equipment.And all your laboratoryequipment isincluded inyour tuitioncost. There isno extra charge-it'syours touse whileyou study at home and on the job afteryou completeyour course!

Earn Your Degree ToBecome A Professional

In Electronics!EveryCIEcourse you take earns you

credit towards the completion ofyourAssociate inApplied Science Degree, soyou can work towards your degree in

stages. And CIE isthe onlyschool that awards youfor fast study, which cansave you thousands ofdollars inobtaining the same electronics educationfound in four-year Bachelors Degree programs!Write for details today!

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Unlikethe impersonal approach of large class­room study, CIE offers you one-on-one instructionalhelp 6 days aweek, toll-free. EachCIE lesson isauthored by an independent specialist, backed byCIE instructors who work directly withyou toanswer your questions and provide technical assis­

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Easy to usecircuits c , menu-drivenome alive on YO~;tousi! controllederminetl• DC ' •Oh~r~es Circuits

ss Law· K"Voltage Law irchhoft 's

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• n series esistances

Voltage DividI t ersn ernal sourc .

• Voltage regUI~reslstanceDC Parallel C' IO~

Network trcutts• DC serie~-~Current dividers

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Mesh circuit anYS1S

• analysis d branch current

S~perposition TCircuit analysi heory

• B id SIS usmq~ ge Circuits superposition

elta - Wye• Phasor MatheC~nv~ rsions

Phasor th attcs• S. eeryenes AC C" "RC RL Ircuits

, and RLC .Power and circuits

• Resonanc power factorsT euned serie .Parallel re s circuits

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New PROTOLAB™ , a state of the art electronics lab for instruments ... all built-in with easy to use, menu driven,the hobbyist's, student's or engineer's pc. Now, you can mouse controlled PROTOWARp Msoftware. Plus, youbuild and experiment with actual circuits, choosing from get a unique experiment book, featuring over 75 experi­an unlimited number of components, including resistors, ments and circuits. Enjoy countless hours of fun , whilecapacitors, inductors, general impedence, AC voltage learning. And , you won 't blow up your " lab", becausesources, batteries, AC/DC current sources. Then, analyze it's fool proof and safe on your pc.

Oscillo scope

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Resis tor Series /Parallel Circuitdemonstrates current division in

a parallel circuit

' IBM/compatibles require 384K RAM. CGA [640 x200j video display and mouse" Macintosh requires Macintosh 512E. MAC XL. MAC PLUS. MAC SE. MAC II

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CIRCLE 186 ON FREE INFORMATION CA RD

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28

an antenna tuner withouttransmitt ing. or check theSWR of a linear amp lifier 'sinput.

The SWR analyzer has alow-d ist o rt ion RF gener­at o r th at covers 10- 160meters . an SW R br idgethat gives forward and re­flecte d co mponents, and itauto ma tical ly computesand disp lays the SW R. Afrequency-counter outputallows a counter to be con­nected for precise dig italreadout. Operation is-corn­pletely automa tic.

The MFJ-20 7 HF SWRana ly ze r cos t s $99.­MFJ Enterprises, Inc .,P.O. Box 494. M ississippiSt at e , M S 39 762; Tel :6 01- 323-5869; Fa x :601-323- 6551.

HANDHELD LOG ICANALYZER. Targeted foruse by design engineersand field service techn i­c ians , Trace-Tek s LogicBoy is a full-featured. 16­channel. 50 -MH z logic ana­lyzer. The handheld diag ­nos tic and deve lopment

CIRCLE 19 O N FREEINFO RMATION CARD

tool is easy to use. with ex­te ns ive me nus for userprom pting and sys tem set­up. A ll state information.timing data . and menus aredisplayed on the LCD read­out. The Logic Boy weigh sonly 21 ounces w ith NiCdbatter ies insta lled . and isdesigned to be held andoperated with one hand- a

convenience when trou ­bleshooting digital circu itsat remote locat ions lackingAC power. It can be cou ­pled with a battery-oper­a ted printer t o fo rm acomple te portable diag ­nost ic and troubleshootingsystem.

The Logic Boy offers 50­MHz operation on all 16channe ls. non-volatile sys­tem setups and referencememory, a bu ilt-in IBM­compat ib le printer port.and a BNC tr igger outputte rminal that lets the logicanalyzer be used as a four­level wo rd recog nizer whenconnected to the externa lt rigger input of most os ­cilloscopes . The Logic Boyis compatible with both TILand CMOS logic levels .and. features 1K x 16 cap­ture-and-reference memo­ry, sy nchronous or asyn­chronous clocking, a clockqualif ier. and program ma­ble trigger delay.

The Logic Boy . co mpletewit h probes . AC wall adapt­er, IBM printer-cable adapt­er, NiCd batteries, and aone-yea r warranty, costs$1795 .-Trace-Tek In­struments, 1301 NorthDenton Drive, Suite 204 ,Carrollton, TX 75006.

GRAPHIC POWERMON ITOR. To help elec­tronics tec hn icians andhobbyists find and solvepower problems . thePowerVisa power monitordetect s all powe r distur­bances th at ca n affec telectronic equipment. Bysimply plugg ing it into anoutlet. a complete powe rana lys is can be made .Wh en any type of powerd ist urba nce-i nc Iud ing

CIRCLE 20 ON FREEINFORMATION CARD

sags , surges, impulses ,failures . waveshape faults,frequen cy errors , high-fre­quency noise , w iring er­rors, and tota l harmonicdistortion-is detected, anLED lights. A disturbancegraph can be printed imme­diate ly or, at the users' con­venience, a text report ofthe ten worst events ofeach disturbance type canbeg e n era ted . T h e'PowerVisa also prints dailyand weekly summaries. Itmonitors true RMS ACvo ltage , AC cu rrent . andte mperature . An RS-232port is included for remoteoperation. The instrumentautomatically se lects ap­propriat e thresholds de­pending on the voltagebe ing monitored , or theuser can choose to man­ua ll y s et the desiredthresholds.

" Help " messages tha texplain its opera tion can beprint ed. and a push of theAdvice button generates aprintout of the type s of dis­turbances that have beenrec orded and the time sthey occurred .

The PowerVisa powermonitor has a suggestedpr ice of $3,295.-BasicMeasuring Instru ­ments, 355 Lakes ideDri ve , Fost er C ity. CA944 04 ; Tel: 415-570-5355;Fax: 415-574-2176.

BI-POLAR POWER SUP­PLIES. The POW series ofsing le -outpu t . b i-polarpower s u p p l i es can

sin k " -absorb curren tfrom external sources-or" source" - supply powerto externa l loads-current.They can be used for ap­plications invo lv ing servosystems and precisiondrives, as variable outputpowe r s upp l ie s . or aspower amplifiers with fre­quen cy c harac t e ris t ic sranging from 0 ± 30 kHz.The power supp lies areavailable with t hree dif­ferent op era ting ranges :+ 35 to - 35 VDC at 1A;

+ 35 to -35 VDC at 5A;and + 70 to - 70 VDC at2A. W ithout switching po­larity, both ga in andpos it ive/negative vo ltagecan be varied continuouslyby adj ust i ng pa ne l ­mounted , 10-turn poten ti­ometers . Co nstant-currentcrossover over load protec ­tion is provided .

The power suppl ies are

CIRCLE 21 ON FREEINFORM ATIO N CARD

available with eit her a topl u g g a g e strap forportab ility, or a built-in rack­mounting frame .

The POW series of sin­gle-output , bi-po lar powersupplies are priced startingat $92 5.-Kiku s u i In­ternational C o rpo ra ­tion, 19601 Mariner Ave­nue, Torrance, CA 90503;Tel: 800 -KIK-8784 .

SURFACE-MOUNT SOL­DER KITS. Two SMT sol­der cream kits. for evalua­tion of component solder­ing using differe nt types offlux systems, each contain250-grams of stenci l-gradesolder cream packed in five

CIRCLE 22 ON FREEINFORMATION CARD

50 -gram " Flexpaks." Thefive diffe rent types of mildlyactivated fluxing syst emsincluded are standard. finepitch. water washable. andtwo with no-clean residues.The latter leave clear. hard.

CIRCLE 50 ON FREE INFORMATION CARD

, ')

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IUlEL CS-5 170100 HIlz, Dual Channel,4-Tr ace , Dela yed Sweep .REG. S1695. DO SALE $1399.95

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FOR MANUFAGURE, MAINTENANCEAND SERVICE OF:• Switches &Relays • CobleConnectors &Ad apto rs• EdgeConnectors • Terminal Strips · Plugs&Sockets• Gold Plated Con nectors • Potentiomete5 • Battery Contacts

CRAMOllN~ DeOxidizerimprovesconduc~vity by ds­solving oxides that formonmetal connectorandcon­tact surloces, eliminating unwonted resistance thatimpedes ele(tricolperlormonce.

CRAMOllN(ll is onoc~ve ingredient thatdoes notrely onsolventsforperlormonce. Dueto theexcel·lentmigrationproper~es, CRAMDlIN (ll coots theen~re

metalsurloce and protects itfrom futureoxidation.

HARD-DRIVE SECURI­TY SYSTEM. Prov id ingpassword access securityfor IBM PC , XT, AT, 386,and compatib le comput­ers, PC Access version 2.1cons is ts of an eas ily-i n­stalled plug-in card and a

RADIO-FREQUENCYFINDER/COUNTER. Themode l 1500A RF finder/counte r from Startek runs

CIRCLE 24 ON FREEINFORMATION CARD

diskette of programs. Ei­ther a valid password or,optionally, a use r-ID and apassword must be enteredeach time the com puter isbooted before DOS wi ll beloaded or executed . Onemast er password and asmany as 15 user pass ­wo rds are allowed . Themaster password must beused to acces s the userpassword list and to selectthe security system 's func ­tions. Ver sion 2 .1 featuresmenu-driven selectio ns fores tab lis hing th e pass ­wo rds and other sec uritysettings, DIP sw itc h selec­t io ns of t h e secur ityboard's address , and a half­size card with a bracket foreasy installat ion. PC A c­ce ss does not modifyCOMMAND.COM or anysystem files , and doe s notinterfere wit h the opera tionof any other software.

PC Access version 2.1has a sugges ted list priceof $ 79 ; d istrib utor andquanti ty d isco unt s areava i l a b Ie . - R e ntonP rod u c t s , P.O . Bo x16271, Seattl e, WA 98116;Tel: 206-682 -7341.

non -corros ive res idues;one is off-fillet residue andthe other is on-fillet resi ­due. Kit 7 provides the fluxsys tems with an Sn62 al­loy, w hile Kit 8 is suppliedwith an Sn63 alloy. Each kitco mes w it h a "Vac­Tweezer" set that includesa vacuum pickup and fivetips w ith various sizes ofclear pads .

Surface-mount so lderKit 7 and Kit 8 are priced at$89 each.-ESP SolderPlus , 14 Blackstone ValleyPlace, Lincoln , RI 02865;Tel: 800-338-4353 .

,DIGITA L CL AM P-ONM ET E R. Th e mode lACO-10clamp-on meter di­rect ly measures AC cur­rent , vo ltage , and resi s-

CIRCLE 23 O N FREEINFORMATION CARD

tance . The drop-proof in­st r ume nt weighs e ightounces and is 63/ 4 incheslong . Its half-inch displa yprovides over-ra nge andlow-battery indica tors. Theaut o rang ing meter pro ­vides circu it protection upto 550 volts. The ACO-10comes with a wrist st rapand a removab le belt clip. A9-volt batt ery, safety te stleads, a carrying case , andinst ructio ns are inc luded .

The model ACO-10 dig­ita l vo lt/amp/ohm meterhas a list price of $89.95.­Amprobe Instrument,630 Merrick Road , P.O .Box 329 , Lyn bro ok , NY11 563; Tel: 516-593- 5600.

CIRCLE 182 ON FREE INFORM ATION CARD

3 for $75 - 10 for $200 - mix or match

CIRClE 26 ON FREEINFORMATION CARD

w hic h redu ces the un­des ired elect r ica l noi sethat causes rece iver de ­sensitizatio n. The AS- l ist he same type of devicethat's used on aircraft andin ground stations to mini­mize electrostat ic inter­ference. It has been mod i­fied for use on antennas toprevent any detuning, evenif it is element moun ted.Th e antenna stat ic d is­charger mounts eas ily toany ante nna, boom, or tow­er and weig hs only oneounce . It offers increasedrange during noisy condi­tions , minimized receiverdesensitization, and lowerantenna no ise on lon gwires, dipoles, yagis for HFthrough UHF, vert icals, TV,and TVRO antennas.

The AS-l antenna staticdischarger costs $ 12.95 .-Static Buster lnc.:3535 Shepherdsville Road,Elizabethtown , KY 42701;Tel: 502- 769-2244. R-E

ANTENNA STATIC DIS­CHARGER. Precipitat ionstat ic and corona di s ­charge noise , whic h canraise the noise level 20 to30 dB above ambient, arebled off by the mode l AS-lantenna static discharger,

costs $9 .00-StartekInternational, Inc. , 398N E 38th Street , For tLauderdale, FL 33334; Tel:800-638 -8050 or305 -561-22 11 ; Fa x:305-561-9133.

CIRClE 25 ON FREEINFORMAT ION CARD

0.25-seconds yie lds a 1­kHz reso lut ion, and a slowgate time of 2.5 secondsyie lds a 100-Hz resolu t ion.A TXCO timebase providesaccuracy of ± 1 ppm .

The unit can be operatedand c harged simu lta­neous ly w ith a 9 ± 12VDC, AC adaptor. The in­put signal of the device iscoup led via a BNC con ­nector on the top, and vari­ous types of probes andantennas can be used tooptimize pe rformance forspeci fic uses and freq uen­cy ranges .

The model 1500A radio­frequency finder/ countercosts $99.95 , the factoryinstall ed N iCd batteriescost $20.00 , and an ACadapter/battery charger

on 110 VAC, 12 VDC, orrec ha rgeab le NiCd ba t­teries, and is small enoughto fit in a shirt pocket. It ishous ed i n a r uggedanod ized-a lum inum cas eand we igh s less than 9ounces with the batteriesinsta lled . The highly sen­siti ve instrum ent can beused w ith its te lescop ingRF antenna to accurate lyand ea s ily identify andmeasure transmit frequen ­c i e s f ro m h a n d h e Id ,mob ile, or stationary radiotransmitters.

The 1500A has two over­lappi ng ra nges-1-500M Hz and 200- 1500 M Hz.Two " gate" or "sample"t imes are switch se lecta­ble . A fast gate tim e of

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No costly school. No co mmuting to cla s s.The Original Home-Study co urse preparesyou for the "FCC Commercial Radio­telephone License." This va luable license isyour professional "ticket" to th ousa n ds ofexciting jobs in Communications, Radio­TV, Microwave, Maritime, Radar. Avionicsa nd more . . .even start your own business!You don't need a college degree to qualify .but yo u do need an FCC License.

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PASSPORT TO WORLDBAND RADIO; from In­ternational Broadcast­ing Services, Ltd., Box300 , Penn 's Park, PA18943; $16.95.

This magazine in bookformat could be describedas the TV Guide for radio ,N ation a l Ge ograp hic ,Co ns umer Repor ts , and

Time ro lled into o ne. Its384 pages are filled wi th ar­ti cle s on topic s rangin gfrom music behind the IronCurta in to how to write torad io s ta t io ns for fre egoods , from inte rna t ionalpolitics and curren t eventsto how to get sta rte d inwo rld-band listening, fromAl istai r Cooke's long-run­ning Letter From Americashow to the Salt Lake Citywor ld-band sta tion t ha tbroad cast ed roc k-n-ro llused by Ame rican troops inPanama to dr ive Norieganuts . In-depth co nsumerrepo r ts provid e com­parative ratings of portab leand tab le-top radios , aswell as a review of a world­band rece iver for cars.Compreh ensive programguides are listed by time,cou ntry, and channel. New­comers to the hobby will

apprecia te ti ps on w hatfeatu res to look for in aworld -band receiver,a glos ­sary of term s, and informa­t i o n al ar t ic les . In t e r­spersed th rough out th ebook are helpful hints, defi­nitio ns, and pointers, alongwith int riguing photographsfrom around the wo rld anddozens of advert isementsfo r radi o s ta t io ns andequipment.

1991 ELECTRONICCOMPONENTS/COM­PUTER PRODUCTSCATALOG; from Jam­eco , 1355 ShorewayRoad , Belmont , CA94002; Tel: 415-592-8097;Fax: 415-592-2503; free.

Featuring just about ev­erything the electronics en­thusiast or computer buff

CIRCLE 28 ON FREEINFORM ATION CARD

cou ld need, the new Jam­ec o ca ta log offe rs tool s,tes t equipmen t, cables ,co nnectors , IC 's , mothe r­boards, computer kits ,floppy- and hard-d isk driv­es , computer accessories,and more. New to this edi­tion of the catalog are two386 computer kits, 38 6mo therboards, a 2400 ­baud mini external modem,and a 9600-baud fax board.

The Jameco catalog fea­tures full product descrip­t ions , pho tographs, andpricing information.

TONER CARTRIDGERECHARGE: Kits-Sup­plies-Service ; fromChenesko ProductsInc. , 62 North ColemanRoad, Centereach, NY11720; Tel: 800-221-3516or 516-736-7977 ; Fax:516-732-4650 ; free.

CIRCLE 29 ON FREEINFORMATION CARD

W ith the high price ofnew ton er cart ridges fo rlaser printe rs, many peopleprefer to use cart ridgesthat have been c leanedo ut , mod i f ied , and re­charge d. This cata log of­fers t on er-cartr id ge re­charge products and ser­vices, and explains how torecharge ca rtridges usedwith laser printers includingthe HP LaserJets, App leLaserWrite rs , and manyothers . Six do-it -yourse lfkits include full inst ructionsfo r rec hargi ng. For thosewho wan t t o s tart a re­charge business, the cata­lo g o ffe rs a co mp leteselection of products- in­c lud ing ge ne r ic t on er,graphic to ner, fixing rods,sealing st rips , plugs, bags,to o ls , and vac uums-atbulk prices. For those who

aren't handy with toner car­tri dge recharging , or areshort on time, the catalogoffers a mail-in rechargingservice.

SOLDER CREAMS : ACOMPLETE GUIDE TOTHE SELECTION ANDUSE OF SOLDERCREAM; from MulticoreSolders, CantiagueRock Road , Westbury,NY 11590; Fax :516-334-7098 ; free withrequest on company let­terhead. ·

This comprehensive 24­page brochure explains anddescribes the formulation,applica tion meth od s, anduses of solder creams. Itcover s the various alloys,fluxes, propert ies, and rhe­ology of solder creams forsu rface -mo unt appl ica­tions, as well as tech niquesfor deposit ion, reflow so l­dering , and cleaning. Achart that illustrates good

~~

SOLDER CREAMS

CIRCLE 30 ON FREEINFORMATION CARD

wo rk ing pract ices is fol­lowed by exp lanations ofhow to apply solder creamsfor vario us pu rpos es . Ath ree-page glossary ofcommonly used technicalterm s is also incl uded inthe book let.

"TlmOJ:DC»:D-<

31

Electronics Engineers & Designers!

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8225P $19.95Te sted progra ms for mos tmathemat ical computing needs.233 pp.

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9321 $49.50This time-saving handbook pro­vides prob lem-solving calcula­tions for engineering design.production and research . 4 16 pp.Counts as 2

10015 $42.95The most up-to-date introductionava ilable on the many facets ofISDN . 320 pp. Counts as 2

3059 $34.95Master the art of modeling, ren­dering, and animating on yourIBM" rc.524 pp . Counts as 2.

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3237P $24.95This handy guide demonstrat essuch advance d features asdebu ggin g applicat ion s andVirtus l 8086 Mode . 432 pp .

9813 $39.95Cover s logic design , registe rtra nsfer design , architect ure .programming and more. 578 pp.

3131 $26.95Assemb le your own powerfu lmicrocomputer system . . . it' seasy and inexpensive . 224 pp.

3279 $36.95Master the pro ven repair tech­niques of an expert electronictechnician . 570 pp. Counts as 2

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2672 $49.50Linear integra ted ci rc uits ­specifications, prices & data .614 pp .

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3138 $60.00Mo re than 700 state-of-the-ar telectronic circuit designs for on­the-job use. 738 pp . Counts as 2

1938 $60.00Over 1.300 useful and versat ileelectronic circuit designs.768 pp. Counts as 2

3258 $27.95Step-by-step instructi ons fortroubleshooting and repairingthe latest in electrical equipment.310 pp .

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3203 $44 .50An indispensible guide to tech­nology from composition to ap­plication s and test ing. 400 pp.Counts as 2

9244P $18,95Th is revised and updated editionis both a comprehens ive ,industry-wide reference , and avaluable collectio n of projectideas. 5 12 pp .

3329 $29 .95A practical introduction to thelatest devices , techniques , andshielding methods . 239 pp .

3098 $44. 50A comp rehensive overview ofCAD /CAM, CAE, and CIMconcepts , capabi lities and appli­cations . 438 pp . Counts as 2

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315 1 $39 .95Provides detai led insight intoevery aspec t of the enginee ringdes ig n process- fro m th epre-concept phase thro ugh thelife-cycle costs and commercialapp lica tions. 334 pp.Counts as 2

3037 $24,95Build your ow n neural network­ing breadboards- systems thatcan store and retrieve like thebrain ! 160 pp .

9290 $36 .00Provides many never-before ­publ ished tr ou bl esh ootingtechniques and case histories.3 15 pp. Counts as 2

9305 $59.50The solution-oriented handbookfor practicing engineers at alllevels . Co ntains hund reds ofinformative illustrations anddiagrams demonstra ting keyprinciples . 600 pp. Counts as 3

How the Club Works:

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DYES! Please accept my members hip in the ELECTRONICS ENGINEERS& DES IGNERS BOOK CLUB and send my 3 volumes listed below bill ing me$4.95. If not satisfied . I may return the books within 10 days and have mymembership cancelled . I agree to pur chase 3 or more books at regular ClubPrice s during the next 2 year s, and may resign any time thereafter. A ship­ping/handling charge and sales tax will be added to all orde rs .

INTRODUCTORY to-DAY FREE EXAMINATION

~ -----------------,[~D~IELECTRONICS ENGINEERS

I '" & DESIGNERS BOOK CLUB sMI <:.:: 0 Blue Ridge Summit. PA 17294-0860

IIIIIIIII Name

I AddressI City

I State

I Signa tureValid for new members only . Foreign applicants will recei ve specia l orde ring instruct ions. CanadaI must remit in U.S. currency . This order subject to acceptance by the ElectronicsEngineers & DesignersBook Club. DRE291

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IRONCLAD NO-RISK GUARANTEE: If not satisfied with yourbooks . return them within 10 days without obligation !

YOUR PROFESSIONAL BOOKSTORE BY l\'lAIL: Every 3-4 weeks.you will receive the EE&D Book Club News descr ibing the Main Selec­tion and Alternates. as well as bonus offers and special sales, with scoresof titles to choose from .

YOUR BENEFITS: You get 3 books for $4,95 plus shipping & hand­ling when you join. You keep on saving with discounts of up to 50 %as a member.

All boo ks are hardcover unless num ber is followed by a " P" for paperbac k.(Publis hers' Prices Shown)

©1991 EE&D Be, Blue Ridge Summit, PA 17294-0860

BONUS BOOKS: Starting immediately you will be eligible for ourBOil/I S Book Plan with savings of up to 80 % off publishers' prices.

AUTOMATIC ORDER: If you want the Main selection, do nothingand it will be sent to you automatically. If you prefer another selection.or no selection at all, simply indicate your choice on the reply form provid­ed. You will have at least 10 days to decide. As a member . you agreeto purch ase at least 3 books within the next 2 years and may resign atany time thereafter.

EXCEPTIONAL QUALITY: All books are quality publishers' editionsespecially selected by our Editorial Board .

ELENCO & HITACHI PRODUCTSAT DISCOUNT PRICES

4-Channel, IOOMS/s Madel Introductory Price100M5Is (2SM5/s on 4 channels simultaneously), 100MHz, 4kw x i ch., 2kw x 2ch., 1kwx 4ch. VC·6145 $ 4,695.00

DelayedSweepLightweight (13Ibs)2mVSens .3 Yr Warranty

Model Y-l065Shown

This seriesprovides many new functions such as CRTReadout, Cursor measurements (V-1 085/1 065/665) ,Frequency Ctr (V-1085), Sweeptime Autoranging andTrigger Lock using a 6-inch CRT. You don't feel thecompactness interms of performance andoperation.

V-660 60MHzDual Trace $1,195V-665 60MHz Dual Trace w/Cursor $1,345V-1060 100MHz Dual Trace $1 ,425V-1065 100MHzDualTracew/Cursor $1,695V-1085 1OOMHz Quad Tracew/Cursor $2,045V-1100A 100MHz Quad Trace w/Cursor $2,295V-1150 150MHzQuad Tracew/Cursor $2,775

$ 3,049.00

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VC·6045

VC·6025

RSOs (Real -Time & Storage Oscilloscopes) From HITACHI ~The RSO • its the new solut ion ~~I

View, Acquire, Test, Transfer and Document Your Waveform Data

V-212 Hitachi Portable Scopes$435 DC to 50MHz, 2-Channel, DC offset

DC t0 20MHz function, Alternate magnifier functionDual Channel Y-525 CRT Readout, Cursor Meas. $1,025

Y-523 Delayed Sweep $995

V-422 40M Hz Dual Trace $795 Y-522 Basic Model S895

Compact. Full Feature Models

Low Cost/High Value Models

40M5Is. 100MHz, 4kw x tcn., 2kw x 2ch.

20M5/s, SOMHz, 2kw x 2ch.

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20M5/s, 20MHz, 2kw x 2ch. VC-6023 $1,749.00

RSOs from Hitachi feature suchfunctions as roll mode, averaging, savememory, smoothing: interpolation, pretriggering,cursor measurements, plotter interface, and RS-232C interface. Whh the comfort of analog and the power of dighal.

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Allscopes includeprobes, schematics, operators manual, and 3 year (2 yrs for Elenco scopes) world wide warrantyonparts & labor. Many accessories available forallHitachi scopes. Call orwrite for completespecificationsonthese and many other fine oscilloscopes.

Digital LCR MeterLC-1801

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Starting from scratch you build a complete syslem. Our Micro-Maslertrainer teaches youtowriteintoRAMs,ROMsandruna8085microproces­sor, whichuses similarmachinelanguageas IBM PC.Youwillwrite!heinitial instructions to lell theIlO85processor toll9t started andstore !hosoinstructions in permanent memO<)' ina 2816 E' PROM. Teaches you allabout input and output por1s , compuler timers. Build yourown keyboardand leam how to scan keyboard and display. No previous computerknowledge required. Simple easyto understand instruction teachesyouto write in madline language.

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36

(f)

ozoa:f­oUJ....lUJ

oo«a:

ra nges from 0.01-10 seconds . ormore. The OE 10 has four built-inga tes-O.OI. 0.1. 1.0 and 10 sec­onds-as well as programmabl egate ti mes th an ca n be set fro mless than a microsecond to mo rethan 28 seconds. The gate lime.a lo ng wit h t he timebase os­ci llator frequency (10.000 MHz).determines the resolution of thefreq ue ncy measu reme nt. or thenumber of s igni ficant d igi ts thatca n be di splayed.

A frequen cy measurem ent maya lso be prescaled-that is. beforeth e s ignal to be measured en te rsth e frequency cou n ter. it is divid-ed by an in teger numbe r. Prescal­ing allows signals to be measuredthat a re higher in freque ncy than "the counter is normally ca pable HJof m ea suring. The OE1 0 s u p- ::0

cports three prescaler values: 4. }>

16 . a nd 64. However. prescaling ~requires that th e ga te time mus t CD

be multiplied by th e prescale to CD

37

Frequency measurementsA frequency measuremen t is

defined as a number of cycles ofa n incoming s ig na l occurringduring a g ive n time peri od. Theunit of frequency is Hertz (Hz). orcycles per second (cps) . A fre­qu en cy m ea surement is per­formed by cou n ting th e numberof cycles occurring within a spe­c ific ga te time. which typicall y

cou n ters a t a fraction of th e cost.it a lso has many fu nct ions th atn o ben ch co u nte r can m atch .The PCIO ope ra tes in MicrosoftWindows. which a llow the user totake m easurements while per­forming other tasks. The Win ­dows en viro n me n t a lso a llo wsdata to be s hared with other pro­g ra ms. Data logg ing and a u to­matic softwa re ca libra tion of th etimeb as e a re a lso provided . Fi­nally. th e PC10 can directly tune areceiver to the measured fr e­quency using th e co mputer's se­ri al port.

How ev er. be fore we di scusshow the PCIO op era tes a nd howyou can build one for you rself.let's first talk abou t how univer­sal frequency cou n ters work .

IIVE

VEV TE

JOEY GRASTY and BILL SCHULZ

FREQUENCY C O U NT E RS IIAVI, COME A

lon g way s ince Hewlett Packardint rod uced the 524A b ack in195 2. It was a huge instrument.co n ta in ing more than 70 vac­uum tubes . but it cou ld measurefrequencies up to 10 megahertz.and time intervals as s mallas 100nanoseconds. In late 1988. a proj­ec t began to reduce th e majorparts of a univers al frequencycou n te r into a s ingle integratedcircu it. which grea tly in creasedthe performance a n d measure­ment ca pab il i ty of fr equencycou n ters built wi th th is new IC.Th e project cu lminated with theOEIO. an IC that cou ld directlymeasure fre q ue ncy up to 240MHz a nd measure time intervalswith resolution to 0.1 nanose­conds . The OE 10 was then in cor­porated into the PCIO. a hi gh­performance univers al frequen­cy-cou nter board for IBM PCIXTIAT a n d co m pa tibles-and nowvou can bu ild it you rself.. The combl nauon of a PC and afreq uency co u nte r produces apowerfu l to ol us eful for a widera nge of measuremen ts . Not onl ydoes the PCW con ta in most ofthe features of more expe ns ivelaboratory bench top frequency

A

B

C

o

FUNCT

GATE ==:5111INPUTDSPTESTMP--~~

WR·:=~ll~RO-CS-

FIG. 1-BLOCK DIAGRAM of the OE1 0 gate array. The dev ice is packaged in a 44-pinplastic leaded chip carrier.

~-..... XTAl 2

XTAl l

~s-"'" ADCS­

~~-........ ADClK

AOOATA

I~~--l"~ SOASCl

BATTLOWlCOTEST

(fJoZoex:I­oLlJ...JLlJ

oo«ex:

3B

retain the same resolution. Forexample, with a divide-by-4 pre­scaler, the gate times for the samenumber of significant digits be­come 0.04, 0.4 and 4 seconds.The final gate time of 40 seconds,is not supported by the OElO.The PC 10 board contains twocascaded divide-by-4 prescalers,allowing prescales by 4 and 16.That feature raises the PClO'smaximum measurable frequencyto 3 GHz.

A period measurement, the in­verse of a frequency measure­ment, is the length of time of onecycle of a signal. A period mea­surement counts the number ofclocks of the time base oscillatorbetween two consecutive risingedges of the input signal. Aperiod average function is alsobuilt-in, allowing 10 , 100 , or1000 periods to be measured andaveraged to give a final value. Pro­grammable averages are alsoavailable.

One difficulty with frequencymeasurements is getting goodresolution at low frequencies . For

example, with a gate time of 1sec­ond, a lO-Hz signal will be dis­played as 0.0000010 MHz, withonly one hertz resolution. Tocounter that problem, the OElOcan be programmed to perform areciprocal, or inverse frequencymeasurement, which is a periodmeasurement with the measure­ment converted to frequency. AlO-Hz signal has a period of 0.1seconds, or 1,000,000 countswith a lO-MHz timebase . Thatyie lds a frequency measurementof 10.00000 Hz, with six digits ofresolution . Better yet, the re­ciprocal frequency measurementrequired only 0.1 seconds to give6 digits of resolution, comparedto the l-second frequency mea­surement that gave a paltry 1 dig­it of resolution! The disadvan­tage of this measurement tech­nique is that the gate time is nolonger fixed; it is the same lengthas one period of the signal that isbeing measured.

Short period measurementshave the same resolution prob­lem as low-frequency measure-

ments . A signal with a 1­microsecond period, for example,gives a count of 10 with a lO-MHztimebase: a resolution of only 1digit. If that measurement is per­formed as a reciprocal periodmeasurement (a frequency mea­surement), the same signalwould be measured as 1.000000MHz with a I-second gate, whichgives a period measurement of1.000000 microseconds, or 6 dig­its of resolution. The main disad­vantage of reciprocal periodmeasurements is that the lengthof the measurement is greatly in­creased, and single-shot eventscannot be measured.

A time-interval measurementdetermines the time between twoevents. A time-interval measure­ment starts when the OEI0 de ­tects a rising edge on the A input.The measurement ends when arising edge is detected on the Binput. Any additional edges de­tected on the A input are ignoreduntil a rising edge is detected onthe B input. The number ofcounts of the time base oscillator

TABLE 1-0E10 REGISTER MAP

MSEL1/MSELO

GATE1/GATEO Frequency (00) Period (01) Interval (10) Ratio (11)

00 0.015 1 1 100,000

01 0.15 10 10 1,000,000

10 1.05 100 100 10,000,000

11 10.05 1000 1000 100,000,000

INSEL Frequency (00) Period (01) Interval (10) Ratio (11)

0 A A AlB AlB

1 B B C/O C/O

Address D3 D2 D1 DO

00000 MCO MCOD MCOC MCOB MCOA

0000 1 MC1 MC1D MC1C MC1B MC1A

00010 MC2 MC2D MC2C MC2B MC2A

00011 MC3 MC3D MC3C MC3B MC3A

00100 MC4 MC4D MC4C MC4B MC4A

00101 MC5 MC5D MC5C MC5B MC5A

00110 MC6 MC6D MC6C MC6B MC6A

0011 1 MC7 MC7D MC7C MC7B MC7A

01000 MC8 MC8D MC8C MC8B MC8A

01001 MC9 MC9D MC9C MC9B MC9A

01010 TCO TCOD TCOC TCOB TCOA

01011 TC1 TC1D TC1C TC1B TC1A

01100 TC2 TC2D TC2C TC2B TC2A

01101 TC3 TC3D TC3C TC3B TC2A

01110TC4 TC4D TC4C TC4B TC4A

0111 1 TC5 TC5D TC5C TC5B TC5A

10000 TC6 TC6D TC6C TC6B TC6A

10001 CREG 1 GATE1 GATEO MSEL1 MSELO

10010 CREG2 EXTGATE TSOURCE DT INSEL

10011 CLRCNT - - - -

between the two even ts is the ndis played as the m easured valuein secon ds. A time interval ave r­age fu nction is al s o availab le.with built-in ave rages of 10 . 100 .a n d 1000 time in terval s. Pro ­grammab le t ime-inte rval ave r­ages a re also present.

A rati o measurement is a fre­qu ency measurement wi th an ex­ternal s ignal repl acing the time­base osc illator. Therefore , in­stead of giving a measurement inHz. the OEIO measures the ratiobetween the input si gnal and thereference s ignal. If th e two sig­nals h ave identical frequency. the

display will read l.000000. Ratiom easuremen ts a re espec iallyuseful for tu n ing radio receiversan d transmitters to a referencefrequency. Resolution of a ratiomeasuremen t is de termined byse tt ing the number of co u ntsthat the reference signal mus tmake before di splaying the ratiomeasurement.

An oth er u s eful feature is apulse-width measurement. Th ism easurement is performed b ymeasuring the number of cou n tsof the time-bas e oscillator b e­tween a rising edge and a fallingedge (a po s itive-going pulse) or

between a negative edge a nd apos it ive edge (a negative-goingpulse). The OEIO does not sup­por t pulse-width measuremen tsdirectly. bu t using a simple exter­nal circuit and the time-intervalcapability. pulse-width measu re­men ts a re easy to accomplish.

Theory of operationFigure I is a block diagram of

the OEIO gate array. The devi ce ispack aged in a 44-pin plastic lead­ed chip carrier. The OElO typ­ically draws about 25 rnA from a5-volt supply. The OEIO can becon figu red for two modes of oper­ation by setting the MP pin to log­ic a or logic 1. Logic a configuresthe device for stand-alone opera­tion. used for buildi ng handheldor benchtop universal counters(which will not be discussed inthis a rticle); logic 1 configuresthe device for microprocessor­co ntrolled operation. the modeu sed for this project. When con­figured in microprocessor-con­troll ed mode. the microprocessorbus in terface becomes active andcontrols all chip operations .

Tabl e 1 shows the internal regi­s te r map of the OEIO. The OE IOhas a 5-b it address bus and a 4­bi t data bus that allow access tothe internal registers. The firs tten locations . MCO-MC9. are the10 BCD digi ts of the main coun­ter. where the resul ts of the mea­su re me nt a re stored. The mosts ign ificant digit is MC9. Sincethe digi ts a re BCD. only binaryvalues 0000 through 1001 are val­id. The least significant di git.MCO, can on ly be read, not writ­ten, and any write clears MCO.The 28 -bit b ina ry terminal cou n­ter occupies the next seven loca­ti ons . TCO through TC6 . Theterminal counter controls thelength of the measu remen t.

The n ext two locations are con­trol regis ter 1 (CREG1) and con­t ro l register 2 (CREG2). TheMSELl and MSELO bits controlthe type of measurement to bep erform ed . Th e GATEI a ndGATEO bit s control the gate timesfor a frequency measurement .t he n u m b er of a verages forperiod or ti me-interval measure­ments . or the number of cou nts rt1for ratio measu remen ts . Bit IN- ~SEL co n t ro ls which input (for ~

frequency or period measure- ~

ments) or input pair (for time in- u;terval or rat io measurements) is ~

39

Va;

C39 Rl1 R19 fI20R17 2-7pf751< r l K 33K l K

~, C3S1 0M~z 8.2pf

~D(O_n

DO ..C35

IU pf

1947pF

4900

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PIIl3eI; C34 , 3

330Pf C36330pf d\·m",~ V", " 47.tHCT125

I=fREO'PREl 1121 ICS 210K DEla

[lliC) f-t TeTEST MCOMP 35RESET

~ r--i." l CDTEST u.:INC ~ ACDATA XTAl2...!!!!L..- a PREO

PREI8 XTAl l 369

cs TIMEBASE

10RDWR,--

~ BATIlOWI , PH 9 " INA

I( L ~115 INB

P1H a T(lIenU 16 Ir,c' I( I 2 I' DO 17 IND SDA~ID,r. 7 3 A1 81 17 01

~ FUNCT SClI( .( ...2 62 16 D2 GATEPlF 6 5 ~ ~ 16 D3 ~ INSEl

I> ;A5 B5~~ D4 DISPTEST:flL-.U os DO ~ DATAO AOClK~I 8 ~~ ~ 12 06 D1 25 DATAl ACCSrPlD 4 I rr=; AS B8~~

02 26 DATA2 TESTOIF-D 2l DATA3p,c 3

IrG.-!- DIA

AD f, ADDROPIB 2 Al

7 1.2ADDR1ADOR2

'M ~ ADDR3ACDR..

I , P10 3''--

MPA(0_.)

1P'N 30 I 1C2 Ala .. ..)

I~ nHrn«I , P1M 29 2 lAl lV1 18 AO

I( I .. 1A2 1Y2 16 AlP1l 28

l A3 lY3 ~i A2 Ie.1/ ZOla

7 1, P1H 24 11 ' M 1Y4 9 A7 OIl

~1 2A1 2V1 7 ."'A1"1 11 011/15~ :~~ 5

ASA? 12 02 ~rf1L ~ AS 03 CSAEGlI( I M Ai 13

PIJ I7 2M 2V4 3

~14 O.1

C 226 15 05 CSDACI( ~

lG 1 16 06 7PIK 2l 2G 07 16

1/ 1 17 ).!L18 DB19

~ 110I , PIG 23 ~ ::;8 1/

I L1e3 14 11 3

91, P' F 22 "Hen« 114I( --+ l Al lVl 11 AS

PIA " A9

I( 8 11.2 1Y2 14

8 ~~ ~~~ 12P1l «

I( PI'" 45 " 2A1 2Vl~13 21.2 2V2+--"Ie PIK 11 I ~ 2A3 2V3C

...---!I 2A4 2Y4NI /

~V'" IOW-

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2 1) 1/41~~SIIl 3 S9

R4AS 10K 4

5 ) Jv41~Sbll 6 53sws

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1'::c3 " ~ 8 ... 12 ' '--4 -" 5

13 )h}~~11 1153

r.....~

D6

02

D3

os

A

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lOW

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RESET

FIG. 2-THE PC10 INTERFACE is an B-bit industry standard architecture (ISA) bus used inIBM personal computers and compatibles.

enoZoa:t­olJ.J...JlJ.J

ois<l:a:

used for the m easurement. BitDISPTEST co ntrols the displaytest. which is not used in the mi -

c ro p r ocesso r mo de , B itTSOURCE determines whe therbuilt in or proarammable gates

are u sed . Bit EXTGATE is usedon ly for manufacturing tes t.

Regis ter CLRCNT provides as imple way to clear both the maincounter an d the terminal cou n ­ter, A write of any value to this

40

tal, XTALI, con trols the frequen­cy of os cill ation ; the fre quencymay be set precisely using trim­capacitor C39.

That's all we h ave room for, sowe'll h ave to fin is h up this storynext month. We will then fin ish "'T1

up the discussi on on the PC10 Hlcircu itry, we' ll talk about the op- ~

t ion al extern al amplifier board , »JJthe AP1OH, an d we' ll show you -<

what is involved in building both ~

of them. R-E ~

Note: The following items areavailable from OptoelectronicsInc., 5821 N.E. 14th Ave ., Ft .Lauderdale, FL 33334 (800)327-5912 , in Florida (305)771-2050, FAX (305) 771-2052:Complete Kit of all parts to buildthe PC10, including software,$299; OE10 ASIC, $49; PC10 PCboard, $59; software, $5; pro­grammed PAL, $19; assembledand tested PC10, $339; completekit of all parts to build the AP10H,$179; AP10H PC board, $39; ma­chined and painted cabinet, $49;6-foot 25-conductor straight­through cable, $20; assembledand tested AP10H, $229. SendSASE for priced out parts list.Include 5% shipping and 6%sales tax when shipped to Flori­da address.

PC10 PARTS LIST

All resistors are Y4-watt, 5%, un- IC22-74LS86 quad XOR gateless otherwise noted IC23-74ALS12 triple 3-input NAND

R1-2200 ohms gateR2-not used IC24-LM339 quad voltageR3-R6, R21-10,OOO ohms, Va watt comparatorR7, R1D-4990 ohms, 1% IC25, IC26, IC29--MAR6 MMICR8, R9--10,OOO ohms, 1% IC27-UPB582C high-performanceR11-R14-20,OOO ohms, 1% divide-by-four prescalerR15, R16, R21-10,000 ohms, Va watt IC28--CA3199Egeneral-purpose dl-R17, R3Q-75,000 ohms, YBwatt vide-by-four prescalerR18, R2Q-1000 ohms, YB watt D1 , D2-HSMP3800 surface-mountR19--3S,OOO ohms, YBwatt pin diodeR22, R23-75 ohms, chip resistor Q1-Q3-2N2907 PNP transistorR24-91 ohms, chip resistor 04, 05-PN2369 NPN transistorR25-R28--1000 ohms, chip resistor Other componentsR29--47 ohms, chip resistor J1-BNC bulkhead (R141 -306)R31-100,OOO-ohm potentiometer J2-SMB right-angle PC boardCapacitors connector (R114-665)C1 , C3, C4-10 J.lF, 25 volts, radial RY1-RY3-SPDT DIP reed relay, 5-

electrolytic volt coil, form 1CC2-22 J.lF, 25 volts, radial elec- L1-L3-100 J.lH choke

trolytic P2-female DB25 connector (ITTC5-C33-0.1 J.LF, 50 volts, monolithic DBU-25S-AA)C34, C36-SS0 pF, NPO P3-SMB plug, cable (R114-082)C35-47 pF, NPO S1-4-position DIP switchCS7, CS8--8.2 pF, NPO XTAL1-10-MHz crystalC39--2-7 pF NPO trimmer Miscellaneous: seven 14-pin ICC4G-C53, C67-D.001 J.LF, 1206 chip sockets, four 16-pin IC sockets, six

capacitor 20-pin IC sockets, one 24-pin ICC54-C56, C58-C64, C68-0.1 J.LF, socket (O.S-inches), one PLCC44-

1206 chip capacitor pin IC socket, one G57 modifiedC57-SS0 J.LF, 16 volts, radial elec- stamped PC bracket (Globe Mfg.),

trolytic one lug (Zierick # S34), 6-inch 50-C6S-not used ohm coaxial cable RG187(O.1-inchSemiconductors diameter), PC board, solder, etc.IC1-74HCT245 octal tristate

transceiverIC2, ICS-74HCT244 octal tristate

bufferIC4-20L8 programmable array

logic (PAL)IC5-0E10 application-specific inte-

grated circuit (ASIC)IC6, ICB, IC14, Ic1S-not usedXXXIC7-74HCT125 tristate quad bufferIC9, IC1Q-74HCS74 tristateoctal D-

type flip-flopIC11-AD7528 dual8-bit multiplying

digital-to-analog converter (DAC)IC12-TL074 quad op-arnpIC13-AD580 voltage referenceIC16-IC18-74AC11151 eight-to-one

multiplexerIC19--74HCT74 D-type flip-flopIC2Q-74HCOO quad NAND gateIC21-74HC157 quad two-input

multiplexer

differen t devices on th e PClOboard. The address bus and vari­ous contro l signals from the PCare buffered by two 74LS244buffers, lC2 an d IC3. Data buffer­ing is p erformed b y ICI, a74LS245 octal transceiver.

Although the OEIO con tains acrystal os cilla tor, much b etterperformance can be obtained byu sing a temperature-compen­sated crystal oscillator a s thetimebase clock. The 1O-MHz crys-

loca ti on clears both co u n te rs.Likewise, wr it ing any value to lo­ca tio n STARTM starts a m ea­s u reme n t cycle .

To perform a m easurement,clear both cou nters by writing tolocation CLRCNT. Next, programCREG I an d CREG2 for the prop­e r ty pe of m easuremen t , gatetime, an d input s ou rce. If pro­grammab le gate times are re­quired, program the terminalcou nter to the required value. Fi­nally, star t the me asurement bywriting to location STARTM. Theen d of the m easurement cyclecan b e moni tored b y pollingMCOMP, the measurement com­plete pin.

The OE1O h as four signal in­puts : A, B, C, and D. A an d B canbe used for al l types of measure­ments , with the exce ption thatinput A is the only input that canbe used for pres caled frequencym easu remen ts; frequency a n dperiod measurements requireonly one input, an d use inputs Aan d B on ly. Time-interval andratio measurements require twoinputs, N B or C/D. Inputs C andD are u s ed only for time-intervalan d rat io measurements .

The OE1O h as two cou n ters,the main counter and the termi­nal (or ga te) counter. The maincou nter, which is a 36-b it binary­code d de cimal (BCD) cou nter, isused to collect th e measurementdata . It is driven b y a 5 -bitJohnson counter that divides theincoming signal by.10. The ter­minal cou n ter is a 28-bit binarycounter that gen erates gate si g­nals for a frequency or ratio mea­surement, or provides an averagecou nt for period or time intervalmeasurements .

The PC10 interface, sh own inFig . 2 , is an 8-b it industry stan­dard architecture (lSA) bus u sedin IBM personal computers an dcompatibles (but not PS/2 com­puters). The PC10 is con tro lled bythe PC th rough 32 in put/output(110) ports. Since the PC decodesonly the bottom 10 bits of the I/Oaddress, the bas e address of theboard is s et b y the four DIPswitc hes (S1). The PC10 decodelogic consis ts of a programmablear ray logic (PAL) device, IC4 , a74LS86 quad X O R gate, IC22 ,four pull-up resistors R3-R6 ,and a 4-pos iti on DIP switch, S 1.The 20L8 PAL decodes the I/O ad­dresses into s ign als that enable

41

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42

(f)

~zoa:I­oW--lW

6o<a:

start and stop frequencies anddividing by ten. All markers areindicated on the front panelLEO·s. Figure 1 shows a sweptsine output of the sweep/gener­ator displaying such markers at25% intervals along the horizon­tal graticule lines.

When you are in the RUN mode.the markers should be turned offwhen sweeping. A momentaryovershoot could occur that is notactually present if the markerswitch was on during sweeping.That effect is less likely to happenat higher frequencies .

The amplitude level of theswept sine-wave output may be

varied from 10 millivolts to 5volts peak-to-peak by the SINE

LEVEL control. The outputImpedance is about 700ohms, and the output

level is maintainedwithin 0.5 dB from 10

Hz to 100 kHz . Twoon-board trimmer

potentiometers al­low adjustment ofthe sine shape toas little as 0.5%total harmonic dis-

tortion. The very actof sweeping gener­

ates its own type ofdistortion, which can

be minimized by usinga long-duration sweep.Another feature of the

READ mode is its capabilityto move between the five

markers and cursor with theSKIP button. and stay at a posi­tion with the HOLD button. Whenheld at a particular position, thefrequency of that marker or cur­sor can be read on the front paneldisplay. The Initial display is dim,when It brightens after a few sec­onds you'll have an accurate fre­quency reading.

The cursor Is an additionalmarker which can be adjusted toa particular point of interestwhile in the RUN mode. The usercan move the cursor marker withthe CURSOR potentiometer to anypoint on the swept frequency.The CURSOR is best used to deter­mine the frequency of a point be­fore going to the memory mode.The cursor frequency Is read In ;:Hthe READ mode the same way as ~the marker frequency is read. §;:

Input and output jacks are 10- ~

cated on the front panel for con- u;nection to an audio amplifier or ~

JOHN WANNAMAKER

Build thissweep/marker

generator and dis­cover the audio­range frequencyresponse of your

amplifier orfilter design.

seconds per ten gratlcule divi­sions in each of the three fre­quency ranges. The SWE£<;P

output provides a sawtooth rampfor the X input to an oscilloscope.

The frequency range that isbeing swept uses five markers, orbrightened spots. equally spacedat 25% intervals along the hori­zontal graticules. The first andfifth markers are adjusted to theouter most graticule lines. Thefrequency at each graticule linecan then be determined by tak­ing the difference between the

AUDIOSWEEP/MARKER

GENERATOR

Operating featuresThe sweep/generator

operates In two basicmodes: READ or RUN. In theREAD mode. the frequencysweep range can be programmedby adjusting the START and STOP

multi-turn potentiometers onthe front panel. Three user ad­justable frequency ranges can beswept Into the device undertest-3 Hz to 1000 Hz. 35 Hz to 20kHz, and 3 kHz to 100 kHz. Theuser adjusts the exact beginningand end of the frequency range tobe swept.

While in the RUN mode. each ofthe frequency ranges may beswept in its entirety. or anyportion of the range, as low as0 .4%. may be swept. The upper100-kHz frequency range mayhave up to 12% error over the en­tire band. the amount of error isroughly reduced in proportion tothe amount of the band beingswept.

There Is also a SWEEP RATE

potentiometer, which can be ad­justed from 50 milliseconds to 30

A PICTURE IS WORTH A THOUSAND

words-especially when you 'retrying to determine the frequen­cy response of an audio amplifieror filter design. Our sweep/mark­er generator lets you create an os­cilloscope display that shows theresponse of an of an audio sys­tem. lt can be a useful tool fordesigning and analyzing ampli­fier and filter circuits.

With the sweep/generator. theuser programs a desired frequen­cy range that is swept into theInput of the device under test.The response curve of the fre­quency sensitive circuit is dis­played on the scope screen. Whenusing a conventional storagescope, multiple responsecurves can be superim­posed for"a helpful com­parison of waveformcharacteristics.

The sweep/gener­ator can be used toexamine the tuningresponse of an am­plifier. check cir­cuit stability oreven be used byacoustic engi­neers . Let's take acloser look Into theoperation of this ver­satile unit.

43

FIG. 1-THE AUDIO OUTPUT SINE wave of the sweep/generator shows five equallyspaced markers.

c

a

FIG. 3-FILTER RESPONSES: (a) shows a60-Hz notch filter, a smooth response isdisplayed with a slow sweep of 30 sec­onds, a faster sweep of 1 second givesovershoots and misplaces the notch byalmost 2 Hz; (b) shows a 180-Hz notchfilter with selectable low-end gains , notethe same notch is retraced , indicating cir­cuit stability ; and (c) shows a low-end re­sponse of an amplifier with a 180 Hz notchfilter, one trace covers a 10- to 1010-Hzrange, the expanded view covers a 10- to210-Hz range.

10HzT01010Hz

SWEEPTIME=1 SECOND SWEEPTIME=

30 SECONDS

135Hz b

-Is con nected to the peak-hold in ­put, the peak-hold output is thencon nected to the scope's Y input.The scope will d isplay a contourlin e that follows the positive "en­velope" of the response curve.That rather nice feature has anearly flat frequency respo nsefrom 20 Hz to 20 kHz (with in0 .25 dB)and can be used u p to 50kHz.

The input to the peak-hold cir­cuit sh ould n ot exceed 3 .5 voltspeak-to-peak. The circuit worksade quately with an input as low

that type of scope is u sed , theSWEEP output co n nects to thescope's external trigger. Somedigital-memory scopes, unfor­tunately, do not h ave the memorycapab ility when u sed in the X-Ym ode, n or can they remembers u pe r im p osed sweeps of dif­ferent shapes. To u se the s to ragemod e of a digital- memory scope,the sweep/generator mus t besynch ron ized wit h the scope's in­ternal sweep, and the sweep ratesmus t b e a djusted fo r similartimes . Wh en a di gital-memoryscope is u sed, the SYNC outpu t ofthe sweep/generator con nects tothe exte rnal trigge r of the scope .The dual- trace feature of a dig­ital-memory scope must be u sedin order to ac h ieve a suitable dis­play. Those va r ious con nectionsare s hown in the side bar u nderOperating Instructi ons.

A peak-hold circuit is in corpo­ra ted in the sweep/generator tocreate a clear base line referenceof the frequ en cy response curve.The output signal from the prod­uct to be tested may be fed di­rectly into the scope 's Y inpu t ,but there will be n o well-defi nedbase line because of the mirror­im age of the au dio response. Thepeak-hold circuit overcomes thatproblem by momenta rily holdingthe peak value of each pos it ivealter nation of t he s ignal, a n dthen quickly re ducing to zero.The output from the tested device

Y mode for a proper display.Conventional analog storage

scopes are best suited for u s ewith the sweep/generator. When

- SWEEP SINE - INAUDIO• SWEEP/MARKER

OUT GEN. INAMP- OUT

PEAK HOLD

BOSCILLOSCOPEOX

OY

filter device and an oscilloscope .A conventional, digital memoryor storage scope may be u sedwith the sweep/generator, how­ever the connections are dif­ferent. Figure 2 s hows 'a basicconnecting diagram that can beused with a conventional scope .The swept sine output connectsto the audio input jack , the audiooutputjack connects to the peak­hold input jack of the sweep/gen­erator. The sweep output andpeak-hold outputs of the sweep/generator connect to channels Xand Y of the scope, respectively.The scope must be used in the X-

(JJ

~ FIG. 2-A CONNECTING diagram showso how the sweep/generator can be usedg: with a con venti onal scope.ow...JW

6o«a:

44

MICSPKR

LINEAR AMP.OUT IN

SWEEP SINEa-- - - - - - - - -IIN OUTSWEEP/MARKER GEN. AUDIOAMP.

OUT PEAK HOLD IN

xo OSCILLOSCO PEyo

CURSOR

a

FIG. 5-THE SWEEP/GENERATOR CAN BE USED as a tool in testi ng the acoustic re­sponse of a room. The amplified swept sine wave is projected into a room, and is pickedup by a microphone, whose signals are then amplified with a linear amp and fed into thepeak-hold circuit.

frequency sweep is 50 kHz, at 5kHz per CRT graticule division.The C U R S OR marker, at 52.5 kHz,is at the peak of the curve.

Figure 4-b shows an audio am­plifier's frequency response fro m20 to 120 Hz. The mi rror image ofthe response curve is displayedin both Figs. 4-a and -b becausethe peak-hold circuit is not inuse .

An unusual application of thesweep/generator is in the field ofacoustic engineering. The gener­ator can be used as an aid inacoustic design by amplifying aswept sine wave into a speaker,and projecting that sound into aroom, or perhaps an auditorium.The acoustic response of theroom is picked up by a micro­phone, whose signals are fed intoa linear amplifier. The output ofthe linear amplifier is connectedinto the peak-hold circuit of thesweep/generator. A block di­agram showing the connectionsfor an acoustic response arrange­ment is shown in Fig. 5 . A highquality linear amplifier should beused to pick up microphone sig­nals . Also, the frequency re­sponse of the audio amplifier andspeaker should be known toavoid misinterpretation of theamplifier response with that ofthe acoustic response of theroom.

Figure 6-a shows a line con­tour-display of an acoustic re­sponse of a room with the peak- 'T1

hold circuit in use . The upper HJdisplay is swept over a frequency ::Dcrange of 1 kHz to 3 kHz (200 Hz l>

per graticule division), while the ~lower display varies over a 45 Hz CD

to 5045 Hz range (500 Hz per CD

45

b

FIG. 6-SCOPE DISPLAYS show anacoustic response of a room: (a) shows aline-contour display where the top isswept over 1 kHz to 3 kHz, the bottom isswept over 45 Hz to 5045 Hz; (b) shows afilled-in display which is ach ieved by in­creasing the scope's intensity.

selec ted at 62 Hz, 80-Hz, 97 Hz ,108 Hz a nd 135 Hz. The filter'ss tab ility is illustrated by retrac­ing the same n otch at the variousfrequencies . Figu re 3-c shows alow-end response of an amplifierwith a 180-Hz n otch filter. Onetrace ranges over a frequency of10 Hz to 1010 Hz, the other traceis an expan de d view with a fre ­quency range of 10 Hz to 210 Hz .

Figure 4-a sh ows th e use of acursor in an L-C circuit. The total

Sweep/generator usesAn example of the sweep/gener­

ator being u sed to determi n e thefrequency response of a n otch fil­ter is s hown in Fig. 3-a. The ad­vantage of a s low sweep wit h itsinherent little di s tortion of thesine wave is seen in the two su­p e ri mp o s ed swee ps. Th esmoothest response is at a sweept im e of 30 secon ds. The fastersweep of 1 secon d s hows over­shoots and a d isplacement of then ot ch frequency t hat are n otpresen t at the slower sweep rate.

1\\'0 in teres ting dis p lays a reshown in Figs. 3- b an d -c. Figu re3-b shows five superim pose d re­sponse curves of a 180-Hz notchfilter wi th variable low-end gains

as 35 millivolts peak-to-peak, butany value below 20 mill ivoltspeak-to-p eak will come out as abase-linevalue of abo ut +5 milli­volts peak-to- peak.

Now that we've introduced youto so me of the ope rating fea tu resof the sweep/generator, let 's ex­am ine so me of the scope di splaysit can produce .

FIG. 4-PEAK-HOLD CIRCUIT not in use,note how the mirror image is displayed:(a) shows an L-C tuned circuit, the fre­quency sweep is 50 kHz at 5 kHz per divi-

- sion, with the CURSOR marker at the curvepeak, 52.48 kHz; (b) shows an audio ampli­fier frequency response from 20 Hz to 120Hz.

Theory of operation1Wo PC boards a re used in the

All resistors are 1f.t-watt, 5%, un­less otherwise indicated.

R1-3900 ohmsR2, R5, R1 5, R19, R24, R25, R26,

R39, R41, R58, R59, R77, R99­10,000 ohms

R3, R47-3300 ohmsR4, R28, R31-50,000-ohm potenti­

ometerR6-10,000-ohm multiturn potenti­

ometerR7- 2000-ohm 10-turn potentiome­

terR8-2200 ohmsR9-2000-ohm multiturn potentiom­

eterR10-6800 ohmsR11-10,OOO-ohm to -turn potentiom­

eterR12, R13-1 megohm, 1%R14, R1 7-47,OOO ohms, 1%

- R16:-5000-ohm mLiltitu rn pote riti=- -ometer

R18, R80, R9D-100,000 ohmsR20, R79-1000 ohmsR21 , R23-10,000-ohm potentiome-

terR22-12,000 ohmsR27-500-ohm potentiometerR29,R32,R33,R36,R49,R54,R56,

R67-R71 , R92, R102, R103-4700ohms

R30,R34, R38, R48,R50, R51 , R53,R73, R76, R78, R81 , R82-47,000ohms

R35, R40-68,OOO ohmsR37-15,OOO ohmsR42-1.5 megohmsR43, R83, R87-150 ohmsR44, R46, R91, R100, R101-1500

ohmsR45-50,000-ohm potentiomete r

with SPST switchR52-270,000 ohmsR55-4.7 megohmsR6Q-R66,R94, R95-1000hmsR72-68 ohmsR74-1 megohmR75-10 megohms

grat icu le division).An alte rnate filled-in display is

s hown in Fig. 6-b. The area un­der the response curve is filled­in , r a ther than h avin g on ly abas e line and co ntou r line. Afilled-in display can be achieved

B by increasing the inten sity levelz on the scope . The mat n dis ad­a? van tage of that type of display ist; its inability to display multi ple~ t races.woo~a:

46

PARTS LIST

R85, R86-10 ohmsR84, R87-R89--unusedR93, R97-4.7 ohmsR98-330 ohmsCapacitorsC1, C2, C17, C26, C29, C32, C66,

C68, C69-10 fLF, 25 volts, elec­trolytic

C3, C6, C7, C15, C30, C31, C36,C37, C65, C91, C94-0.001 fLF,Mylar

C5, C9, C11, C14, C23, C28, C33,C61-Q.01 fLF, Mylar

C4, C13, C16, C25, C60, C73, C74,C75-0.1 fLF, Mylar

C8, C64-22 pF, ceramic discC10-470 pF, ceramic discC12, C39-C59, C76-C89--unusedC18-100 fJ.F, electrolyticC19-.0068 fLF, Mylar'C2D-0.004 fLF (four 0.001 fLF 1%

capacitors in parallel), MylarC21-0.8 fLF (0.33fLF and 0.47fLF

wired in parallel), MylarC22-Q.033 fJ.F, MylarC24, C27, C35-0.005 fJ.F, MylarC34,C38, C62, C67-47 fLF,16volts,

electrolyticC63, C95-100 pF, ceramic discC7D-3300 fJ.F, 25 volts, electrolyticC71 , C72-1000 fLF, 25 volts, elec-

trolyticC9D-10 fJ.F nonpolar, electrolyticC92-470 fLF, 16volts, electrolyticC93-see textC95-47 pF, ceramic discC96-Q.05 fLF, MylarC97-2200 fJ. F, electrolyticSemiconductorsIC1 , IC14, IC15-XRL555 timerIC2-CD4040,12-stagebinary ripple

counterIC3-DAC1222LCN D/A converterIC4, ICB, IC7, IC8, IC9, IC23-IC25­

CA3140E op-ampIC5-LM336Z 2.5-volt reference di­

odeIC10, IC26-CA3130E op-arnpIC11-CD4068 8-input NAND gate

sweep/generator: a main board ,co nsis ting of a function ge ne r­ator, cou n te r, and analog-to-d ig­ital co n ve rs ion circu itry, a n d apower su pply bo ard, which alsoincludes the peak-hold circuit. Asc hematic of the main PC boardis shown in Fig. 7. On this board,an XR2 206 functi on ge neratorch ip. lC16, is used as a cu r rent­controlle d os cilla tor. A low- to­h igh fre q uency sweep occurswhen cu r rent flow from grou ndin to p in 7 varies from near zero toabou t 3 milliamps. That current

IC 12-CD4538BCN/BCP orMM14538BCN dual-precis ionmonostable multivibrator

IC13-CD4017 decade counter/di­vider

IC16-XR2206 monolithic functiongenerator

IC17, IC18-RDD1 04 timebaseIC19-74C926 counterIC2D-7812 12-volt positive regulatorIC21-7912 12-volt negative reg-

ulatorIC22-7805, 5-volt positive regulatorQ1 -Q13-2N4401 transistorQ14-2N2219 transistor or

VN0300M MOSFET (see text)D1-D7-1N914 diodeD8, D9, D1D-1N4001 diodeDSP1-NSB3881 , 4-digit,7-segment

LED displayLED1 -7-LN28CAL(US) Panasonic

high-efficiency light emitti ng di­odes

Other componentsS1 , S2-momentary contact push­

button switch, SPSTS3-0N-OFF-ON togg le switch ,

SPDTS4-SPST switch mounted on R45S5-3PDT toggle switchS6-3-pole, 4-position rotary switchS7-SPST toggle switch, 1.0 amp,

125 volts ACT1-120 volts primary, 12.6volts sec­

ondary, 0.6 ampsJ1-J6-RCA chassis mount phono

jacksXTAL1-5-MHz crystalF1-0.5-amp fuseMiscellaneous: Fuseholder, a-con­

ductor 18 AWG line cord, Jamecoenclosure type H2507, DIP sock­ets and hardware.

Note: A set of 2 PC boards is avail­able from John Wannamaker,Route 4, Box 550, Orangeburg,S.C. 29115: $43.00, postage paid,S.C. residents add 5% sales tax.

change takes place when a dig­iti zed ramp, or sweep voltage, isapplied to the bas e of Q1.

The ramp voltage is created byapplying pulses from an astablemultivibrator, lCI, into a 12­s tage binary cou n ter, lC2 . The re­su lting binary-coded outputs areconver ted in to an analog voltageby a 12-bit digital-to-analog con ­verter, lC3 . The output of the con ­verter at pin 1 mus t feed into thevirtual grou n d of op-am p lC4.The output of lC4 h as an appar­en t straight-line voltage rise, but

R2S10K

l~

C13.1

RS910K

RS810K

RH I If10K 7r C37

CURSOR .001

LJ..STOPLIMIT

R7ill2K. . R12STOP • 1MFRED. ..,...C9

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R2212K

1011

1213

IC3 14DAC1222 15

LCN ~_--I

16 +12V

17 - 12V18

1

Cl0T 470pF'='

R56 LEOI h4.7K CURSORd

-

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\

/"t"-o... R37'~, 15K

I rz»:

43

t+12V

131' IC1 1 tt.=:=J.l C354068 2 ' "'T' .005

C23I ::r; .01

Rl3.9K

R3447K

RS7 I ,.....;8::.1.---,15K 2 7

TR f.:.............v-; R4R2 ICl 50K10K XRL555 SWEEP

3 0 _ 6 RATE C5R .01

4 1 SWEEP t-: RANGE MEO.C3 S3 0 FAST -:

.001:r SLQ~ •-: w"-i C4.1

IF12+12V

01 13lN914 11 R

16 IC1 2-a.......---+-....:..:; '12 4538

R35 BCN [ .l..--68K 12 ~ 9

R39 010K 15 14

"::" C25 R38. 1 ~F 47K ;

+12V

n~+ 1 2V

ci b I SI-=lO~F 9bHOL~ 12V

•

+12V R41_In 10K....... ..

,, Ii ' I W-+

, :;:.:~ ;;~6 10_v

F R48 < ~R50 03.?} 1.5K ~ 47K ~ ;>47KlN914

-=

.\... I .r. C31-r- .001

Y' _ B

GND

-R544.7K

1

R473.3K

I I

, 1 j. R5147KI C30

C;::· ~~,~:7":";;-·' -;;;~·~"I~TC;;;H~ .001\R44

1.5K

./>0-.j

FIG. 7-THE MAIN BOARD SCHEMATIC; IC16 IS USED AS a current-controlled os ­cillator-a frequency sweep is generated when current flow from ground to pin 7 variesfrom 0 to 3 lTIilliamps. IC5 is a 2.5-volt precision voltage regu lator used to minimize

0lSP1T883881

R61loon

11b

R66lOon

R62loon R63

10003 6 10 14

fin

R7847K

Rn10K

071N914

C63100pF

"

092N4401

(~

R791K

R7268n

"F: C65.001

sr1\

C60,1

061N914

R704.7K

R694.7K

R741MEG

IC1 974C926

052N4401

1\

R7647K

C61.01

"

042N4401

R7347K

5 16 7 8 8 7 6 5 R75I IC1 8 I I IC17 I10MEG

XTAL1 CJRDD104 RDD104 5MHz4 3 2 1 1 2 3 4

C66 + C6410!lF' .. 22pF;: ...

-::' R83

R81 08 R87 + 12V150n

47K 1N4001 150n I IC20 0 t"- 010P' 7812C73 + ClO :f ~~ C67 2"4401

09 .1 3300!lF G 47!lF rQ1N4001II IC21 10

C71 :+I7912 I

12V+C681000!lF G 10!lF R8247K

BRIGHTEN

LED7LN28CALr»;

R684.7K

051N914

R8510n

C74 *.1

S6-b

o

S6-c

:.~~ ...-_ -l--_ _ --=9c.f---....,~

r-+-_.+- 8:....j r1~1____'

L_+ + -....-:7-j r1.:.,5 +-__-+.......J6 16+--- - ---'=--1 1-- - --+-- - -+- --'

L-_-+-+ --j4 1-1_7 -+- +- -'1-.... -t--lI-- --=3-i 1-1,.;,,8 -+- ...-_ _ ...... ........

1-.... 1-+- 2=1 J.!-1 121-....- - ----- -+-+-------1 I------I----+--~~-_,o<":::_..

...-__...A,/I,1'r-<...-5"-! t-1:.::,3_ _ -I1_ -+-_ -I 1-:..-...J

R714.7K

010

1N4001 I I IC22 ~~I 7805 I .

C75 + C72 G C69 +* .1 * 1000!lF 10!lF *

SHAFT I 6TOS6-a- ' -" '1 0

SINE ~ .....RANGE :

I HIGHI 0-----,IIt »>"l,. ....

120VAC

~S7 Fl =

r---- -,-5A--'rT

R8610n

LO

FIG. 8-THE COUNTER AND POWER-SUPPLY BOARD SCHEMATIC; The time-base forthe counter orig inates from IC17and IC18:A 5-MHz crystal oscillator is used by IC17and isprogrammed via pins 1 and 2. The output of IC18is a square wave which provides a 0.1or1second sampling of the frequency to be measured by the shorting or non-shorting actionofC8.

eno~ . in reality it is composed of 4, 096~ small steps. When the frequencyfa of IC1 changes, the ramp's slopem and durat ion change.o Two inverting uni ty-gain op­~ amps, IC6 and IC7 , provide level­c: shifting controls for a djusting

48

bo th en ds of the ramp. That per­m its a djustable start and s toppo ints as well as some limit-set­ting to protect IC16.

Op-amp IC8 and transistor Q1act as a voltage-to-cu r ren t con­ver te r for the most linear con trol

over the frequency of the IC16.Frequency drift is a problem, es­pecially within the true audiorange, which is at the low end ofthe middle range . When a devi ceoperates in th e audio range, a 1­millivolt drift can cause a changeof 18 Hz. To minimize frequencydrift, a 2.5 volt precision voltageregulator, IC5, is used, and afterone hour of warmup time, the

J5OUT

+12V

R941000

G972200l1F R93

4.70

plied to the inverting input an dan adjustable DC voltage fr omthe C U RS O R potentiometer is ap­plied to the non-inverting input.When the ramp rises to equal theDC voltage, the op-arnps outputfalls to zero and actuates ICI2-bto provide an added marker. Thereason for the complexity of h av­ing two one shots to generatemarkers is that the cursor mark­er must be counted by all mark­ers, not just by ICI3. The.cuas oamarker must hold the astable ICIreset for a period of time.

The MARKER WIDTH control is avariable resistor with a n at­tached switch, S4. When S4 isturned off, there are no markers,but the sweep will cover the samefrequencies as if the m arkerswere present.

The frequency sweep for th emiddle range , or au dio spectrumrange, presents a problem for afour-digit counter display. Reso­lution is poor at the low end if th ereadout is in kHz, and if the read­out is in Hz, the most significantdi git would be missing on th ehigh end. To overcome that prob­lem, the middle range occu p iestwo positions on the S INE RANGE

switch, and the u ser may select areadout in either hertz or kilo-hertz. ;:H

.Th e counter and power-supply ~circuit is sh own in Fig. 8 . The ~timebase for the counter comes ~from ICl? an d ICI8, both a re co

continued on page 70 ~

49

Rl011.5K

J6 G90

It,"'::lOOK

C91• 'OOpF

. OR 2N2219(SEE TEXT)

FIG. 9-A SCHEMATIC OF THE PEAK-HOLD CIRCUIT; IC23 AMPLIFIES the signal fromthe tested device, and reproduces only the positive alternation of the waveform. Tran­sistors 013 and 014 act as switches-when open, C93 charges to the peak value of thepositive alternation, then holds the peak value. The top portion of that charge is onesegment of the positive contour line.

one-second sampling of an un­chang ing frequency can betaken. To keep the u ser aware ofthat, the display is dimmed untilthe readout is valid. An accuratereadout may not be 'ava ilable tothe user until three seconds afterstopp ing on a marker. A three­secon d del ay is provided for allautomatic stops before the dis-play is brightened. .

Integrated circuit IC14 is usedas the one-shot, three-second de­lay for the automatic stops. Athree-second delay is triggeredevery time the marker one-shot,ICI2-b, is activated. The delayedfalling edge out of IC14 at pin 3triggers another one-shot, ICI5,which produces a long duration"b r igh ten " pulse to QlO in thepower su p ply. Once the brightenone-sh ot is triggered, it has thecapacity to remain on for severalminutes, but its time is cut sh or tby ICI2-b , which resets after 15seconds. The H OLD pushbuttoncan exte n d this time if heldpres s ed. The HOLD pushbuttonalso applies a positive voltage tothe input of the 12-stage counterand prevents pulses from en ter­ing. Timers IC14 and IC15 aretypeXRL555 made by Exar. Stan­dard 555 IC's do not work in thisapplication .

The CURSOR marker is gener­ated in a totally different mannerfrom all other markers. A s ingleop -amp, IClO, is used as a com­parator. A digitized ramp is ap-

dri ft averages about 5 or 6 Hz perhou r.

An 8- in put NAND gate, ICll ,provid es a falling edge output at25 % increments as the ramp istaking shape. That fall ing voltagetriggers ICI 2-a , a one-shot mono­s table m ult ivib rator, wh ich thenapplies a lO-millisecond inputpulse to decade coun ter, ICI 3 ,which has one-of- ten d ecodedoutputs. Each of the five countslight separate LED's to indicatewhich marker is in p rogress.

The highlighted m a rker fr e­quency is estab lished b y thetechnique described below. Thepin 9 output of ICI 2-a tr igge rs aone-shot monos tab le multi­vibrator, ICI2-b. Its pulse widthmay be either fixed at 15 secon dsor variable from 10 to 150 millise­conds depending on whether theunit is in the READ or RUN mode.During the time that the voltageat pin? has dropped to zero, asta­ble ICl 's RE S E T pin is h eld andcannot fu rnis h pulses to the 12­stage counter. The cou n te r holdswhatever coun t ex ists a t thattime which ultimately translatesinto a s teady con trol cu r rent atICI6, and a s teady frequency outof it. The contin u ous frequencyout of IC16 is the m arker fr e­quency. Each time t he rampstops, the sweep applied to thescope's X input holds a s teady val­ue. That stops the trace in itstracks and the unmoving elec­tron beam creates a bright spotwhich is the marker. If there is asignal at the Y input, the markerbecomes a brightened verti calline.

The STOP marker is generatedon the cou n t of 4 ,092. After itscompletion, fou r more cou n ts re­turn th e 12-s tage counter to anall-zeros output condition , theramp r eturns to its starti n gpoint, an d a synch ron ized pulseis generate d by trans istor Q2 .That same puls e resets lel3, theLED markers cou nter, an d thevoltage that had previously lit theST O P LED falls to zero. That fallretrtggers ICI2-a and a new se­quence begins.

The built-in counter that di s­plays the marker frequency can ­not give a m eaningful readou twhen it is in the RUN m ode be­caus e t he fre q uency is con­tinually changing. A valid fre­quency readout can be di splayedonly in the READ mode, where a

which has to do with the fact thatat high frequencies, alternatingcurrents tend to travel mainly atthe outside surface, or skin, of aconductor. Since the skin effectessentially removes current fromthe center of a conductor, effec­tively reducing it's cross-sec­tional area, it causes an increasein the impedance of a conductorat high frequencies.

Actually, when frequency ishigh enough, a tube or pipe willhave the same effective resis­tance as a wire of the same diam­eter. That fact can be usedsimplistically to account for theuse of waveguides rather thanwiring at microwave frequencies .But concerning high frequen­cies, how high is high?

Supposedly, the skin effect be­comes important above about 30MHz, but a recent ad for speakercables claimed perceptible bene­fits from reducing skin effect at20 kHz. Soon after, articles ap-

really worth the money?out for sure!

poetically described as a blend ofstraw and chicken manure. Pre­dictably, he soon became dissat­isfied with the quality of the rec ­ord player, and his junior-highand high -school years weremarked by repeated attempts toupgrade the equipment withoutspending any money.

Along came the late '70's, and anew product was aimed at the pu­rists: beastie cables (the namehas been changed to protect theauthor!), which are expensiveheavy-gauge speaker cables. Theold purism surged forward, re­membering the effects of cable re­sistance on damping factor andthe effect of cable capacitance onhigh-frequency response-butthe ads also spoke of skin effect,

Are expensive speaker ca IeThis article tells how we fl u

WILL

"DWTIE"SPEAKER

CABLESIMPROVEYOUR AUDIO?

THE PURIST WILL TELL YOU THAT IF

something's worth. doing at a ll,it's worth doing well-and that'sthe case with the author of thisstory. The author always lovedmusic, and was probably doomedto permanent audiophilia fromday one. Even in 1960 at age 12,when he and his sister pooled re­sources to buy their first 45-RPMrecord (Pat Boone's "Love Lettersin the Sand"), he recalls that,even on a monophonic, crystal­cartridge record player, there wasan audible difference betweenthe quality of a decent LP and the45 . Even though it should havesounded better than an Lp, the 45was bassier, noisier, and some­what distorted, being pressed onwhat a broadcast engineer later

(f)oZoa::f-­oW..JW

oo~ RICHARD A. HONEYCUTT

50

.......... .

FIG. 1-THIS CIRCUIT IS roughly equiv­alent to an amplifier, speaker, and lengthof cable .

Note : The wire must make a com­plete round trip, so there 's 20 feet ofwire in a to-toot speaker cable.

TABLE 1RESISTANCE OF COPPER WIRE

Gauge Resistance(ohms/foot)

RESISTANCE. INDUCTANCE.AND CAPACITANCE OF CABLE

/A. ,

"., YVY 'Y Y

lour} MOO"(OFAMPi :::::: c APPROXIMATION

ICf~ OF SPEAKER

~

Z S P E A K E R

in ser ies with the speaker. Sin cethe s im ple loss calculati on in Fig.2 dep ends upon the com b ined re­sistance of the speaker and thecable, the resis tive power loss willbe related to the damping factor.Thus we can fin d a rela tionshipbetween damping factor an d low­frequency lo s s . In the AudioCyclop edia Howard Tremaine es ­tablished that there is no value intrying fora damping factor great­er th an 204 • Tha t is bas ed on thefact that the speaker's voice-coilres istance appears in the circ u it,an d its value- typically 6 to 7.5ohms for a n S-oh m speaker­sets a practical limit on the bene­fits of reducing other resistances.The effect ive damping factor isequ al to :

TOTALCABLE

RESISTANCE

01 SPEAKERY IIMPEDANCE

1.CABLE RESISTANCE=0.1 x SPEAKER RESISTANCE

2. RESISTANCE PER FOOT =TOTALCABLERESISTANCE

TWICETHEAMPLIFIER-TO-SPEAKER DISTANCE3. SElECT GAUGEFROM TABLE 1

assu m ing a 6-ohm voice-coil re­sistance. With most amplifiersh avlng output impedances onthe order of 0.1 ohm or less, thiswould mean that th e cable resis­tance could b e 0 .3 ohms. The lossin dB corresponding to an S-oh mspeaker fed th rough a 0. 3-ohmcab le is :

=20l0g I 0 ( D SD D)= -O.32dB ~S + 0 .3 c»

That means t hat for a n op- ~timum effect ive damping factor, U;the resistive cable loss should be (0

R VOIC E COIL + R AMP + R C ABLE

A s ta ted amplifier damping fac­tor of 20 would represent a totalresistance of S ohms divided by20, or 0.4 ohms in ser ies with theamplifier. That wou ld g ive aneffective damping factor of:

SD- - - - =1.256D +0.4D

FIG.2-HERE'S THE TRADITIONAL meth­od normally used to determine speaker­cable gauge by loss.

0.0000980.0001560.0002490.0003950.0006280.0009990.001590.002530.004020.00639

o2468

1012141618

cab le for a m p li fie rs up to 100watts feeding impedances of Sohms or more with runs of25 feetor less. For each halving of im­pedance or doubling of a m plifierpower or di stance, the wire sizewould increase by two gauges ; 16gau ge for 100 watts into S ohmsat 50 feet or 4 ohms at 25 feet, etc.That rule of thumb includes asa fety factor so that the los s willalways be less than 10%.

The National Electrical Codespecifies cab le g a uges b asedupon safety considerations; if awire carries too much cu r re n tover a long enough period oftime, it can become dangerouslyhot and start a fire . Going back tothe rule of thumb, a speaker witha n average impedance of S ohmsfed by a 100-watt amplifier willdraw about 3.5 amperes at fullpower. However, even running atfull tilt, it 's unlikely that the aver­age power will be greater thanone-third of your amplifier's max­imum, so the rule of thumb pro­vides a large safety margin from afire-prevention standpoint.

The damping factor can be de­fin ed as the ratio of a speaker'simpedance to the total resistance

peared in professional trade jour­nals mentioning the likes of Lu­cas film using the enormous ca­bles , s o some real res earch was inorder.

The g oal was to find outwhether b eastie cables did infact:• Reduce the amount of powerlos t in the cable enough to pro­vide a s ign ifica n t improvementin effic iency, or• Increase the damping factor ofthe speaker/amplifier systemen ough to provide audible im­provement, or• Provide any significant benefitin the frequency response of thesys tem .No other benefits are claimed forthese cables , so it is \n ot neces­sary to look for undiscovered orpresently u nmeasurable effects.

The problem was attacked bothanalytically and experimentally.The equivalent circuit of a realloudspeaker driven by a real am­plifier through real ca b les issh own in Fig . 1. Any effects pro­duced by the cables must showup in the cable resistance, capac­itance, or inductance. The effi­cien cy and damping-factor ques­tions depend almost exclusivelyupon the cable resistance, where­as the frequency-response ques­tion is mainly a function of thecap acita n ce. Wire inductance isso small compared with the semi­inductive n ature of speake r im­pedance at high frequencies thatit can be ignored, as we will see.

The cable resistance is madeup of three components : the con­tact resistance, the ohmic resis­tance of t he wire, and anycontribution from skin effec t.The ohmic resistance can easilybe found from wire tab les in mostelec t ron ics reference books . Ta­ble 1 shows the resistance of arepresentative sampling of cop­per cables , listed according togauge. For yea rs, selection of ca­ble gauge has been m ade accord­ing to the cr iter ion of 10% loss. Inother words , for a g ive n cablelength, what resistance will giveno more th a n 10 % (0 .46 dB)power los s at the speaker? Figure2 sh ows the calculations involvedin determining that value . Forshort cab le runs , the resultinggau ge is surprisingly small.

About fifteen yea rs ago whenthe author was an audio consul­tant, he would specify IS -gauge

51

TABLE 2-MEASURED CHARACTERISTICS OF CABLES

FIG. 4-A COMPUTER SOLUTION, or prediction, of the model in Fig. 1 yielded theseresults. The worst-case 1055 is well under 1 dB at 20 kHz.

20K10K5K

-- 4-GA. CABLE

2K

using stranded wire that has lessskin effect.

The actual resistance, capaci­tance, and inductance of a cableare distributed evenly along itslen g t h . Telep h on e engineersfound out long ago that, for anal­ysis purposes, a cable's R, C, and ,L can be lumped into a s inglecomponent if certain conditionsare met. The conditions dependupon the attenuation constantand length of the cable. The at­tenuation constant (a) is givenby:IX = Y(R2 +w2L2)(G 2 +w2C2 ) +RG - w2LC12

where R, L, C, and G are the ca­ble's resistance, capacitance. in­ductance , and leakage con ­ductance per unit length , and wis the angular frequency, or 2nf.

The author does not like to lieawake nights solving equationslike that, and tables of attenua­tion constant versus frequencyare not generally available for th ekinds of cables used for speakerleads. However, tables for 19­gauge pulp-insulated telephonecable indicate that a 3-kilometercab le section can be analyzedusing the lumped-constant

200 500 l KFREDUENCY (Hz)

- ---- 18-GA. ZIP

- '--' 16-GA.ZIP

10050

1

~:---- _.-

-:.=.:~ -_:':~ :i":-.. - - -- _._- --- -- - - ---- -- - - - ..1

2

3

420

LEGEND

- - - 22-GA. CHEAP

_ ..- GUITAR CORD

Cable Type C l R*(pF/ft) (f.l.H/ft) (ohms/ft)

22-ga. cheap 10.7 0.29 0.017818-ga. zip 14.0 0.28 0.00720-ga. twist 18.0 0.36 0.01074-ga. cable 50.8 0.29 0.000716-ga. "drop cord" 22.4 0.38 0.006shielded "guitar cord" 105.8 0.30 0.04816-ga. zip 12.5 0.23 0.0127

+ 2

+3

+ 4

*One-way resistance, not loop resistance; that includes the contact resistance ofthe terminations.

nificantlyabove 1, skin effect maybegin to matter. We say may, be­cause it only matters if the totalresulting increase in cable resis­tance causes a perceptible effectin the reproduction. For a fre­quency of 15 kHz, RAc/Rocequals 1.1 when a IS-gauge solidwire is used. Larger wires will ex­hibit a greater proportional in­crease in resistance as frequencyincreases. Ofcourse, since the re­sistance of large wires is lower tobegin with, the actual change inmeasured resistance mayor maynot matter.

Stranded wire is extremely dif­ficult to analyze. Naturally, eachstrand has a certain surface area,so that all the strands connectedin parallel would h ave a very largesurface area. In actuality,though, much of the surfaces ofthe individual wires are in con­tact with each other, making theactual effective surface area vir­tually impossible to determine­unless the individual strands areinsulated from each other, as inlitz wire. At any rate, we can usesolid wire as a worst case to ana­lyze, knowing that we'll really be

SKINDEPTH

OUTSIDESURFACEOF CONDUCTOR

less than 0.32 dB. Just for com­parison purposes, a I-dB cableloss, which would result from a0 .9-ohm cable resistance, wouldresult in an effective dampingfactor of 1.14, which is not muchlower than 1.25.

As mentioned earlier, skineffect increases the effective im­pedance of a wire, and can bebest expla ined by looking at Fig.3. The skin depth of a conductoris the distance into that conduc­tor, measured from the outsides urface, at which current densityis lie times that at the surface.(The symbol e stands for the baseof natural logarithms, andequals approximately 2.72.) For adirect current, the current densi­ty (amperes per unit cross-sec­tional area) is the same through­out the wire. For AC, the currentdens ity is less at the center of thewire and greater at the surface.

At low frequencies, the skindepth (which depends on charac­teristics of the bulk conductormaterial) is usually greater thanthe radius of the conductor,which means that for all practicalpurposes the current density isthe same throughout the con­ductor. Larger-diameter conduc­tors can exhibit measurable skineffect at relatively low frequen­cies, in clud in g audio frequen­cies.

Th e simplest indicator of skineffect is the ratio RACIRO C ' whereRAC is the resistance per unitlength of a wire to alternatingcurrent of a certain frequencyand Roc is the ohmic resistanceper unit length. As long as RAC /

Roc equals 1, skin effect is negli­gible. When RAciRoc rises stg-

CJ) CURRENT DENSllY HEREINo AMPERES PER SQUARE METER IS~ 1/2.12 TIMES THE CURRENT DENSITYa:: AT THE CONDUCTOR SURFACE.

t5~ FIG. 3-THE SKIN EFFECT increases thew effect ive res ista nce of a wire. The skin6 depth is the distance into the conductor at~ which the current density is approximate­a:: Iy 113 of that at the surface.

52

FIG. 7-SEE HOW THE ACTUAL MEASURED CABLE LOSSES compare to the predictedlosses of Fig. 4.

FREQUENCY (Hz)

FIG. 6-THE MEASURED IMPEDANCE CHARACTERISTICS of the test speaker.

20K10K

10K 20K

5K

5K

_ _ 4-GA. CABLE

2K

2Kl K

amplifier and. if the distance isshort. no serious detriment toefficien cy will result . Dampingfactor is degraded slightly whencables 'lighter than I8-gauge areused, as s hown by the loss ex­ceeding 0 .32 dB. But what willhappen if longer cables are used?

From previous measurements.ordinary Romex house-wiring ca­ble is found to have about thehighest capacitance per foot ofany com mon wire. With the fac­tors mentioned earlier that con­trol skin effect, it is also clear thatsmall wires will not experience

500

500 lKfREDUENCY (Hz)

200

- ----- 18-GA. ZIP__.._ _ 16-GA. ZIP

200

100

100

50

50

j,;" !..--~-l.--i-- i'-... -

4

3

2

1 .

-1 -- - -- - - --2

3

420

LEGEND

___ 22-GA. CHEAP

_ _ GUITAR CORD

~ +w~ 0~<J)

~ -

16

14

C7i 12:<:I: 108-~ 8zC3 6UJ0-

~ 4

2

o20

+

+

+

always trustworthy. so the actualresponse of the cables was mea­sured on the setup shown in Fig .5 . The impedance characteristicof the test speaker is shown inFig. 6. Although the amplifierwas flat within ±0.2 dB from 20Hz to 20 kfiz, the amplifier's cal­ibration curve was neverthelesssubtracted from the measuredresults in order to provide max­imum accuracy. The test resultsare shown in Fig. 7.

Initial results seem to indicatethat virtually anything can b eused to connect a speaker to an

method at 1 kH z wi th a total at­tenuation und er 1 dB and aphase accuracy within 5 degrees .Although it may not be imme­diately obvious to the casual ob­serve r. a tten uat ion constan t ispropor tional to the square roo t offrequency, s o that would meanthat the same a ccu racy couldbe expected at 20 kH z if thelength were reduced by

V20 kHz/i kHzthat works out to a bou t 2100feet. Since we rarel y extendspeaker cab les a n ywhere n earthat far. we ca n s afely u s e the

. lumped-constant method withno qualms. That's what was as­sumed in Fig. 1.

Table 2 shows the types of ca­bles chosen for the analysis,along with their measured resis­tance . capacitance. and induc­tance. .The values were measuredusing a Hewlett-Packard 426IALCR m eter and a test frequency of1 kHz. Instead of a .speaker, a re­sistance of 7.9 ohms and an in­ductance of 6.3 microhenrieswere used in the calculations. In­s tead of "real " beastie cables. weused ones that were on hand. in­cluding a very large (4-gauge)stranded cable. If those cablesshowed no measurable detri­mental effects on efficiency.damping-factor. or frequency re­sponse. then th e alleged beastiebenefits would turn out to be so­lutions to a nonexistent problem!

A computer solution of the cir­cuit of Fig. 1 yielded the resultsplotted in Fig. 4 . A lO-foot lengthwas assumed for each cable, andit included the effects of cable ca­pacitance and inductance. butnot the skin effect. Notice thatthe worst-case loss was well un­der 1 dB at 20 kHz.

Computer solutions withoutexperimental verification are not

"Tlmm:IJC>:IJ-<

10K 20K5K2K200 500 lK

FREQUENCY (Hz)

1005020

1

- -~1

2

3

4

FIG. 8-SIGNAL LOSS OF 40 FEET of 12-gauge Romex cable.

+4

+ 3

_ + 2co"0

;:;; +U>

5 00­U>UJ _

a:

FIG. 5-THIS TEST SETUP was used tomeasure the effects on an aud io signa lcaused by speaker cables.

53

-- INCLUDING SKIN EFFECT

- - - R, L, AND CONLY

FIG. 9-SIGNAL LOSS OF 100 FEET of 12-Gauge Romex cable .

50K20K10K2K 5K

FREQUENCY (Hz)

1K500

l

I

........._~

~~.

~~.\

"\- 5

20

-4

+1

+2

+3

- 3

in 0~Ll.J

~ -1ac,

~ -2c:

Earn Your B.S. Degreein

ELECTRONICSor

COMPUTERS

By Studying at HomeGrantham College of Engineering,

now in our 41st year, is highly ex­perienced in "distance education"­teaching by correspondence-throughprin ted materials, computer materials,fax, and phone.

No commuting to class. Study atyour own pace, while continuing onyour present job . Learn from easy-to­understand but complete and thoroughlesson materials, with additi onal helpfrom our instructors.

Our Computer B.S. Degree Pro­gram includ es courses in the BASIC,PASCAL, and C langu ages - as wellAssembly Language, MS DOS, CADD,and more.

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Write or ph one for our freecatalog. Toll free, 1-800-955-2527, orsee mailing address below.

•Accredited by

(JJ the Accrediting Commission of the~ National Hom e Study Councilzo •a:§ GRANTHAM~ College ofEngineeringCi Grantham College Ro ad~ Slidell, LA 70460

s ign ifican t sk in effec t , an d la rgeones will , but even a large pe r­centage change in a la rge wire'ss mall res is tance is of little con ­seque nce. Tryi ng the RAC/R ocva lues for va r ious cable di ame­ters in conju nction with the com ­pu ter analysis, 12-gauge sol idwire is found to h ave abo u t theworst s k in effec t of any cable.

Therefore, if any typ e of speak­er cab le cou ld cause frequency­response p robl ems , the high ca­pacitance a n d the s kin effect of12-gauge Romex s h ou ld ma ke itthe ideal bad exam ple. Anotherrun was m ade u sing a 4 0- foo tlength of Romex, b oth in to adummy load a n d into the tes tspeake r. In the graph of Fig . 8, wesee a h efty Y2-d B droop at 20 kH z,compared to the respons e a t 20Hz. The overall s ignal loss an ddamping-factor degradation a reless than those of the s maller ca­bles that are shown in Figure 8,due to the lower resi s tance of 12­gauge cable.)

Since that still wasn 't s ignifi­cant. a com puter si m u lation of100 feet of 12-gauge Romex wasperfo r med, w it h respons e ru nclear out to 50 kHz. The results

a re s hown in Fig. 9. Here, at las t.is something the b eas ti e peoplecan sink their teeth into ! Anyo newho can h ear 50 kHz will find afu ll 4 .5-dB drop resu lti ng fromthe u s e of 100 feet of 12-gaugeRo mex- p rovid ing , of co u rse,they're u sing a n a m pli fie r a n dspeake r that can reprodu ce it. Ofcou rse, the s k in effect is s t ill onlya bout h alf a d B, a n d effect ivedampi n g is n o t d egraded , somayb e they'd better drop thosepoints from their ads.

The results of that ra ther in­volved bit of resea rch clearly in d i­cate that ordinary speake r ca­bles , including the ones that anyknowled geable au dioph ile wou ldsneer at, do n ot sign ifican tly de­grade frequency response. Theyvindicate the rule-of-thumb ad­vice (18-gauge for .100 watts , 25feet. in to 8 oh ms ) except for as light d egrada t ion in dampingfactor ; 1.21 with a 25- foot cableru n. For optim u m damping fac­tor, that rule shou ld be changedto 18-gauge for 100 watts, 20 feet.into 8 oh ms. Also, on ly 20-gauge,22-gauge, a n d gu itar-cord cablesare a serious detriment to damp­ing factor. R-E

}'tJ/l lI rc 1IS('C/.:('I' ofsonictruth? You'\,c 1'0 111 (' to the

right place'

54

BUILD ANEGATIVE ION GENERATOR

LAST MONTH WE STARTED

building our negative-iongenerator. Let's now finishup the project. We were dis­cussing the flyback trans­former and what the vari­ous connections are usedfor.

Pin 7 is used as ground,since it presents the highestresistance between itselfand the flyback transformeroutput lead, which 3x39.4isoften quite short to avoidhigh-voltage breakdown, sobe careful how much insula­tion you remove. The bot­tom of the voltage-tripler PCboard, with D6, D8, andDlO, and the attachmentpoints of the ground wireand both high-voltage leadswas shown in Fig. 5 in lastmonth's article.

Figure 6-a shows the topof the main PC boardmounted in the case andheld down with RTV, whileFig . 6-b shows a drawn ex­ploded rendition, giving thesame components withgreater clarity and defini­tion, but adding the top ofthe voltage-trtpler PC board,connecting leads, and emit­ter needle.

The wire shown balancedon top of the emitter needlein Fig. 6-b is the rotor for anion motor discussed later.The foil pattern for the mainPC board in the prototypediffers from the one shownin this article, primarily dueto Tl mentioned in the parts list,which differs from the one usedin the prototype.

In the prototype, the resis­tances between the lower-voltagetaps and the flyback transformeroutput lead were measured, andthe tap corresponding to thehighest resistance (about 100ohms) was taken as the groundterminal, since it was electricallyfurthest from the output lead.The low-vol tage taps generallyhave numbers stamped on themetal bracket surrounding theferrite core, numbered clockwise.

Build this negativeion generator andput some charge

in your life.

ANTHONY J. CARISTI

WARNING!! This article deals with andinvolves subject matter and the use ofmaterials and substances that may behazardous to health and life, Do not at­tempt to implement or use the informationcontained herein, unless you are experi­enced and skilled with respect to suchsubject matter, materials, and sub­stances. Neither the publisher nor the au­thor make any representation as for thecompleteness or the accuracy of the infor­mation contained herein, and disclaimany liability for damages or injuries,whether caused by or arising from the lackof completeness, inaccuracies of the in­formation, misintepretations of the direc­tions, misapplication of the information, orotherwise.

In the prototype, the tapused as ground happened tobe pin 7.

Although almost anyflyback would work in thisproject, use one from asmall-screen black-and­white TV. It'll usually besmaller and have a betterturns ratio, but make sureit's wired for positive out­put, and has an open ferritecore for the new feedbackand bifilar primary wind­ings.

Note the manufacturer,model, and chassis numberof the TV you salvage itfrom, in case you need moreinformation about it later.Either that, or go to any TVservice store and buy a newone, but know the specificsabout it in advance, includ­ing the maximum safeflyback transformer outputwinding voltage, and thenumber of turns in theflyback transformer bifilarprimary and output wind­ings.

If your flyback trans­former has a high-voltagediode attached to its outputlead, remove it beforeadding the new feedbackand bifilar primary wind­ings. Then use an ohm­meter to find the trans­former taps coming off ofthe flyback transformer out­put Winding. One tap is thehigh-voltage common, orig­inally going to the TV chas-

sis; use the highest resistancetap as ground. In the versionshown here, which was used inthe prototype, pins 1-3 are hid­den by the ferrite core, while pins4-7 are shown.

Figure 7 is a magnified view ofthe feedback and bifilar primarywindings, showing how they'readded; use 20-24 gauge enamelwire, for ease of handling and ad- ~

OJequate breakdown voltage . Use ::D

Mylar tape to insulate both new ~feedback and bifilar primary ~

windings from the ferrite core. <0

Start with the feedback Winding, ~

55

C/)ozoa:f­oW.....IW

6o<:a:

56

wrapping a thin layer of tapearound a clear part of the corewhere the feedback winding willgo. Us e nine inches of magnetwire , five inches for the turnsthemselves and two inches foreac h lead, and wind five clo s eturns around the core.

At the end of the fifth turn.form a Ll-loop about 4 inches longas a center tap, and then wind anadditional five turns in the samedirection. as shown. Secure thefeedback winding with tape.mark the start of the feedbackwinding with a "1." the Ll-loopwith a "2." and the end with a "3."using masking tape; rememberthe direction of the feedbackwinding.

The bifilar primary winding isn ext . Although you can windboth halves adjacent to one an­other. as shown in Fig . 7. the per­formance should improve if yousuperpose them, actually wind­ing one halfon top of the other foroptimal coupling . 1\vist twopieces of magnet wire together.with five turns spread along theentire length as a twisted pair. forclose proximity between the twowires during the winding pro­cess. At one end of the twistedpair, mark one wire with a "4."and the other with a "5."

Obviously; for the center tap inthe feedback winding. if youbreak the wire segment makingthe loop at the point where itbends, there's no electrical effecton the feedback winding. pro­vided you route both segments ofthe loop (now two separate leads)to the same pad on the PC board.Thus. if you prefer. you can breakthe loop at the point of the bend.

However, in the case of the bi­filar primary winding. you reallyshould make an effort to super­pose both halves. one on top ofthe other. However. if you do that,you have to wind both halves inthe same direction, and in thatcase, if you bend the enamel wireinto a loop, you'll have to spreadboth ends after completing thefirst half, in order to retrace it onthe second half. Thus, it's proba­bly easier in that case to phys­ically break the wire. and windthe second half separately.

Start with those ends, and al­lowing four in ches oflead length .wind six turns of twisted pairthrough and around the core inthe same direction as the feed-

PARTS LISTAll resisto rs are V4-watt . 5%, un less Other components

otherwise noted. F1--{).S-amp slow-blow fuse with holderR1-1000 ohms, PC-board mounted po- NE1-120-volt AC neon-bulb assembly

tentiometer with 47-100K built-in series resistor forR2-220 ohms the plug -in version (Radio ShackR3, R4-S60 ohms (the former for the 272-712)

astable-flyback transformer combina- NE2-neon bulb, type NE2 (not the parttion, the latter optional for the battery- number). optional for experiment (seeoperated version) text)

RS-R6-200- and 40-megohm ser ies S1-SPST toggle switchhigh-voltage focus div ider, RCA S2-SPST toggle switchSK38681D1V-1 , used for an optional T1-18-volt center-tapped transformerhigh-voltage range extender for a con- (Radio Shack 273-1515)ventional high -impedance (10 - T2-standard TV flyback transformermegohm) voltmeter (see text) (see text)

R7-2.7megohms Miscellaneo us : P lastic caseCapacitors (7.5 x 4.25 x 2.25-inches, Radio ShackC1-1000 lLF, 25 volts, electrolytic 270-224), enamel magnet wire, three-C2-100 lLF, 16 volts, electrolytic wire line cord, emitter needle (madeC3-C8--{).001 lLF, 10 kilovolts, ceramic from either straight pin or sewing nee-

disc die), RTV siliconrubber, heat sinks, fourC9-<>.001 lLF, 500 volts, ceramic disc, alkaline "0" cells (optional for battery

optional for aluminum can/neon bulb operation), 2-liter plastic soda bottle,experiment (see text) and a sewing needle.

Semiconductors 01, 02-1N4004 sil- Note:' The fo llowing are availab le fro micon diode Anthony J. Carist i, 69 White Pond

03, 04-1N4148 silicon diode Road , Waldwick, NJ 07463: Two05-01o-RCA SK3067/502 high-voltage etched and drilled PC boards (one

diode, 12 kilovolts PIV each for the main and voltage-tr iple rLE01-light-emitting diode for the bat- sect ions) for $15.95, 1C1fo r $3.25, 01

tery-operated version and 02 for $2.75 each. Please add01, 02-TIP31B NPN transistor $2.00 for postage and handling withIC1-LM317T adjustable voltage each order; NJ residents please add

regulator 7% sales tax.

FIG.6-THE TOPOF THE MAIN PC BOARD, held down with RTV(a), and an exploded view(b), with D2, D4, and D6 not visible. You can see the new feedback and bifilar primarywindings, wit h Mylar tape insulating them from the ferrite core. The enamel leads are"1"-"6," as in Fig. 1; " 2" and " 5" are paired.

ROTOR

EMITTERNEEDLE

b

"T1mCDJJC:l>JJ-<

to the mai n PC board with suit­able hardware. Using Figs. I, 2,an d 7 as a gUide, co nnect thefee d back a n d b ifilar pri m a rywin dings after cutting the leadsa n d scrap ing the enamel. Re ­me m ber, the re a re two leadsmarked "2 " and two marked "5 ,"s o d on 't mix them up. Wh enfinished, position the leads toavoid a short, and be su re the

really two se parate wires fro m thebifilar primary wind ing. In Fig. 6 ,on flyback trans former T2 , youcan clearly see the low-vol tagetaps. Their correspo nding num­bers a re s tamped on the metalframe of the ferrit e core , increas­ing clo ckwi se when fac ing thetaps , s o th at pin 7 , the grou nd , isat the lower rtght .

Mount the flyback transformer

back winding. The directions ofboth n ew feedback and bifilarprimary windings must be cor­rect to ach ieve oscillation. Placethe closely wound turns directlyover the feedback winding, an dsecu re the biflla r primary win d­ing to the core with plastic tape .

Scrape away 3fs-inch of enamela t the four en ds of the bifil ar pri­mary Winding , and locate the un­m arked en d con necte d to wire"4" wi th an ohmmeter. That 's thecenter tap of the bifilar primaryWinding, an d is marked with a"5 ," u sing a piece of maskingtape. The duplication is delib er­a te, an d it'll be connected to theother "5 " wire later; mark the re­maining wire with a "6. "

You can also see the new feed ­back an d bifilar primary wind­ings, a n d the Mylar tape insulat­ing them from the ferrite core .The enamel wires are numbered''1'' -''6 ,'' as in Fig. 1; rememberthat "2" and "5" are paired. Lead"2" is really a loop in the feedbackWi n d i ng, wi th t he e na me lscraped off the en d where it'sbent an d folds back , while "5" is

FEEDBACK ANDBIFILAR PRIMARYWINDINGS OVER~

MYLAR TAPE

57

TO MAINPCBOARO___------A~----_,

/ "1" "2" "3" "4" "5" "5" "6'"

rro-I ~~I [ WINDING PRIMARy"l I

: I (ONEWINDING WINDING : I

: : WITH C.T.LOOPl (TWO SEPARATE : :WINDINGS)

FIG. 7-THE NEW FEEDBACK and bifilarprimary windings, wound on the ferritecore of the flyback transformer, using20--24 gauge enamel wire and insulatedfrom the ferrite core with Mylar tape. Dothe feedback winding first, then the bifilarprimary winding. Position all leads toavoid a short, and be sure the high-volt­age common is grounded (see text) .

htgh-vol tage com mon goes togrou nd .

Preliminary checkoutCheck the power-supply be fore

connecting the voltage trip ler.Us e a voltmeter to b e s ure theflyback transformer high-voltageoutput lead isn't s horted, or ashock h aza rd cou ld occur; an os ­cilloscope wou ld be usefu l. Also,you need some way to measurehi gh voltage; if you don't have ahigh -voltage meter, you can use avoltage divide r w ith a normalmeter, as shown in Fig. 8 with a100 :1 ratio.

The RCA focus divider shownis a stan dard TV par t, u s ed toreduce the potenti al at the CRTanode for use on the focus elec­trode. It h as a 200- an d a 40­megohm resistor (R5 and R6) inse r ies internally. To achieve 100 :1reduc ti on, R6 goes in pa rall elwit h R7 (external) and a h tgh-im-

GAV

-l-T-T2.4V

II

II112.8V

tI_.1_

II

-\a

T=43J.1S(l=23.26kHz)

TYPICAL COLLECTOR WAVEFORM

TYPICAl BASE WAVEFORM

III

I'"

GND

GND

b

. FIG. 9-NORMAL ASTABLE WAVEFORMS from the base (a) and collector (b) of either 01or 02. With ICl set to 3-4 volts DC, the fundamental is 23.26 kHz. Both are irregular, withsharp, narrow spikes, upward for the collector, downward for the base. The fly backtransformer you use may create different waveforms, so expect variations.oR6

40MEG

HVDC TV CRT FOCUS DIVIDERRCA PARTI SK38681DIV-1

R5200MEG

HVIRED WIREl

o

WHITE BLACKWIRE~-.J>I\fIr.< .,,----i WIRE

enoZ FIG. 8-IF YOU HAVE NO HIGH-VOLTAGE~ voltmeter, this RCA focus divider extendsb the range of a voltmeter with at least a 10­~ megohm input impedance by 100:1, so itui reads up to 20 kilovolts on a 200-volto scale. R5 and R6 are in series, and R6o goes in parallel with both R7 and the DCri voltmeter.

pedance DC voltmeter. The DCvoltmeter used needs a t least alO-megohm input impedance toavoi d loading. If the meter is setto 200 volts fu ll-sca le , it's fu ll­scale range will now be 20 kilo­volts.

Turri the power off before con­necting to the final h igh -voltageoutput terminal at the anode ofDlO , and dissipate the remainingvoltage to ground with an insu­lated clip lead. Set Rl midway, ap-

pl y power, and measure t hevoltage across C2 . As you adj ustR l , you shou ld see 1.25- 5 voltsDC or more. Set Rl for about 4volts DC, and don 't proceed untilyou do .

Check the orientation of a llsem iconductors a n d e lec ­t ro lytics, di s connect the bi filarp ri m a ry wind ing center ta p(marked wit h a "5" ) to remove theoscillator load, and troubleshootthe power supply until you find

58

t

8

LI.... 61/ 8 INCHES _ ..-

THE FOIL PATTERN OF THE main PC board in the negative ion generator.

the fault. If you use batteries, becertain their terminal potential isat least 6 volts DC.

With ICI set to 3-4 volts DC,measure the astable fundamen­tal frequency with a scope, If pos­sible ; it should be about 20-30kHz. Figure g-a shows a typicalcollector waveform of the pro­totype, for either QI or Q2. Itsamplitude is 2.4 volts pop, doublethe DC voltage obtained from ICI ;it goes 400 millivolts aboveground, and 2 volts below Fig. 9-bshows the base waveform; its am­plitude is 12 .8 volts pop, going 8.4volts above ground, and 4.4 voltsbelow. Both of the waveforms arequite irregular, with sharpspikes, upward for the collector,downward for the base , gener­ated by the high inductance ofthe flyback transformer outputWinding.

Since the inductance, resis­tance, and number of turns inwhatever flyback transformeryou use may differ considerably

by comparison with the versionused in the prototype, as well asthe current gains and saturationvoltages of both QI and Q2, thewaveforms shown here may alsovary considerably, so expect vari­ations. The waveforms shownhere are shown purely to illus­trate typical responses, not asironclad guaran tees of whatyou'll see.

If you don't have a scope, toucha large screwdriver with a plastichandle to the flyback trans­former output. If the oscillatorisn't running, there'll be nospark, so the phasing is wrong.Try reversing wires ''1'' and "3, "and then check the orientation ofQI, Q2, D3, and D4, and the T2connections. When you get theastable working, disconnect thepower and let CI -an d C2 dis­charge.

Final checkoutConnect the voltage-tripler to

th e flyback transformer. For the

connection from high-voltagewinding to transformer and C3,use wire rated to at least 5 kilo­volts, preferably I8-gauge rub­ber-covered test lead. The com­mon of the high-voltage assemblycan be made using ordinaryhookup wire since it's at groundpotential. Don't forget the trans­former and voltage tripler com­mon connections .

With the circuit fully as­sembled and power off, connectthe high-voltage voltmeter adapt­er or a high-voltage DC voltmeterto the 'emitter needle and com­mon with suitable clip leads.Don't go near the high-voltageoutput. and position the clipleads to avoid arcing . Applypower, and note the meter, ad­justing RI for - 9 to -14 kilo­volts. Any more , and you'llgenerate ozone, an undesirablebyproduct, which has a peculiarodor. Correct any arcing or coro­na by insulating the connectionwithRTV.

"T1mcoJJc»JJ-<

1J2-INCH SEGMENTBENT /fJ PUNCH

RIGHT ANGLES INDENTATION

T1r~ ,=_31_NC_~_ES ,_,._ .·,4 -----= 31NCHES

YFLATTENED

REGION

EM ITTER________NEEDLE

SODA ~BOTTLE ~\

NECKJ '-

--- - - 6"- --- -

a b~ .., "'"'. ~-

FIG.10-THE ROTOR FOR AN ION MOTOR; it's a 7-inch piece of16" gauge wire, with two V,-inch pointed ends at right angles to the 6-inch center section, as shown in (a). The centeris flattened, with an indentation made in the middle with a punch (b).

59

FIG. 11-AN EXPERIMENT TO SHOW NEGATIVE ions charging a nearby insulated metalobject to high voltage. Negative ions travel through the air, collecting on the empty can ona rubber mat, with an earth ground. As negative ions hit the can, charge builds; at 90-100volts DC, NE2 fires. The flash rate increases as distance decreases, or when the emitter isaimed at the can.

Cf)

oZoa:f-o aDO __ ....~ La ICi ,.. 33/ 8 INCHES .--ca: THE FOIL PATTERN OF THE voltaqe-trlpler PC board in the negative ion generator.

pi ece of gauge 16 wi re wi th bothen ds sharpe ned to fine p oints ,and bent at right angles, as de­pi cted in Fig. lO-a. The bent endsare each 0 .5 inch long, wh ile thema in body of the rotor is 6 inch eslong . The m iddle of the centersection is s lightly flattened in avise, an d an indentation is madeon one si de wit h a punch, in theexact center of the 6-inch seg­ment, as s hown in Fig. lO-b. Youhave to find the exact bal ancepoint , in order to balance the ro­tor on the emitter needl e at theindentation point of the 16 gaugewire.

However, Fig. lO-b shows therotor from below, with the righttip pointing upward, and the leftpointing downward , Thus, therotor s h own ro tates clockwisewhen view ed from b elow, a n dcounterclockwis e when vie we dfrom above. When the indenta­tion is on the bottom (the r ighttip pointing downward and theleft pointing upward) , the reverseis true. In Fig. lO-a , the ro tors h own rota tes clockwise whenviewe d from above, s ince the tipsare rever sed in orientation tothose of Fig. lO-b. You can ob­vlously make the rotor turn in ei­ther direction as long as bothrotor tips face in opposite direc­tions.

The em itter needle won't workwith its point covered . Instead,the en ds of the rotor now becomethe em itters . Since negative ionsare em it te d in opposite direc­tions from each en d ,' it spins likean a irc ra ft propeller, reachinghigh angu lar spee d in just a fewseconds,

Actually, the word "em itted" isa misnomer, s ince n either then eedl e nor the rotor actually ab­sorb or ge nerate ions, per se .Ra ther, pola ri zed a ir moleculescollide with the s u rface of thepointed tips of eit her the needl eor the rotor, absorb ing electronsfrom the molecules , or releas ingthem to un-ionized ato ms. Theabsorption p roces s producespositive ions , the latter genera­tion proces s p roduces n ega t iveions ,

S ince the effect ive di s charges urface a rea is doubled whe nu sing the rotor, as opposed to theneedle, the negative ion dens ityem itted fro m each ro tor tip isabou t half of that emi tted fro m

co n t i n ued on page 70

.'-

selves to any particles , and fall tothe floor or a nearby grou nde dobject. Other phenomena cana lso demons tra te that it reall ydoes em it n egative ions. The "ionmotor" is qui te dramat ic , an dproves the exis tence of n egativeions and that they can performwork . Ion propulsion is a viablemeans of space travel, s ince esca­pi ng ions at h igh velocity can pro­d u ce s peeds a p p roaching thespeed of light in free space. Theio n -m otor .expe r trnen t d emon­strates the principles that are in ­volve d with Newtonian act ionand reaction.

An ion motor can be built asshown in Fig. 10; it's just a 7-inch

NEONBULBNE1

-

C9.001500V

NEGATIVE_ IONS- --- ---.- -- -======--

-- ~-- - -- ---~-~-=-

r ..

INSULATINGBASE

Using the ion generatorYou can u se the negative ion

ge nerator as an a ir purifier, toclear a roo m of s moke, dus t , orpollen. As the n egative ions arege nerated, they'll atta ch them -

Don't a rc the hi gh voltage toground with powe r on to observea s park , or yo u' ll dam ag e thehi gh vo ltage r ectifi e r s . Yous hould do so when power is off,when no s hock haza rd ex ists.Unplu g the line cord and touchthe grou n d prong to the emittern eedl e ; otherwise you ca n us e aninsulated clip lead connected togrou n d on battery-operated ver­s ions.

60

DGGliOUBLESHOO.,INa

liD[J)0

The horizontaloutput transistor is

a critical componentin any TV set.

Let's examine someof the procedures

involved inmeasuring its output.

BRIAN PHELPS

FOR ANYONE W H O HAS EVER TRIED T O

repair a television with defectives ignals th roughout, or changed aho r izontal ou tpu t transistor onlyto h ave it fail once more. we h avea tec hnique that ca n save hoursof work and n eedles s repla ce­ment of parts . All you have to dois check the "HOT pulse." or thesignal a t the collecto r of the hori­zontal output transistor. Let's seewhy th is waveform is so impor­ta n t, an d so me key proceduresfor measuring the s ignal.

The HOT pu lse is importantbecause it performs many func­tions other than jus t sweep ingthe CRT beam h orizontally. So meof the key functions of the h ori­zontal output waveform are:• It generates 0.7 amps of h ori­zontal deflect ion cu r re nt eve ry63. 5 microseconds.• It generates a 700-1 .500 voltspeak-to-peak retrace puls e every63. 5 micros econds .

• It generates 15 .000-30.000volts DC for the picture tu be.• It generates 3.000-8.00 0 voltsDC for the focus circu it.• It delivers "trace-de r ived" high­cu r ren t DC power from 16 to 30volts to ope rate mos t circuits .• It deli vers " ret race-derive d"low-current DC power of 185 to220 volts.• It provides 6.3 volts for thepu lse cu r ren t of CRT filaments.• It is a critical safety feature.• It provides accu rate pulse volt­ages for the tu ner 's frequency­synthesis power so u rce.

What to look forThe h or izon ta l output p u lse

su pplies operating voItages forthe entire TV It is therefore themos t impor tan t wavefo r m t ocheck on eve ry TV b efore an dafte r changing parts . Note: Inorde r to make any of the follow­ing measurements. you r scope

must be capable of measuring.and have input protection up to 2kilovolts or more. Als o. a digital­readout os cillos cop e. a lt houghnot essentia l to troubles hooting.will make it easier to make themeasurements.

The firs t th ing to check whenanalyzing the horizontal outputpulse is the wave shape ; it shou ldlook lik e the one shown in Fig. 1,an d be sym metrical in shape du r­ing the retrace time. A wide peakat the top of the retrace. or deepsaddle con ditions. can be causedby an off frequency or glitch inthe h orizon tal t ransistor base­drive s ignal. Such p roblems areoften caused by a change in theva lue of t he output-t ransistor

""T1ti m ing capacitors. or by an exces- rns ive load on a B + su pply. :0

cAny excessive ringing or noise }>

is a clear indicati on of de flect ion- 3!sys te m proble m s . s uc h as a <0cracked integra ted high voltage CD

61

rOClJS

e

FOCU S

MODEL SC61

AU V£C TOR

u ,, :;.y;o<1o¥

oS EI'JC:: OF<E

INTENSITY

MODEL SC61

FIG. 5-THE TIME DURATION of the re­trace pulse should be between 11 and 14microseconds; 12.83 microseconds inthis case .

of the waveform. Some di git alscopes are equ ipped to measu repor tions of a waveform with a de­lt a- time fea ture . To make thatmeasurement on a digit al scope, .align the pulse so that the top ofit is at the 100 % graticu le mark­ing an d the bottom is at the 0 %marking, using the volts/d ivis ionand calibrat io n k nobs. (Makesu re your scope will allow accu -

continued on page 70

FIG. 4-THE FREQUENCY of the wave­form is important ; here it is measured tobe 15.7343 kHz.

MODELSC61

·~M."J' '''·''''

"

An VECT ORINU NSlT'fC·;:" . c.,.,

H ' OC.. ..." . ..

oSEI'JC::OF<E

frequency to be 15 .7343 kH z. Ifeveryth ing checks out s o far, youknow the condi tion of the regu­lated B + su pply, that the TV isnot in the sh u t-down m ode, andthat the h or izontal oscillator islocked to the co mpos ite videosync pu lse .

The duty cycle of the hori zontaltrans istor ou tpu t waveform ishelpful in troubles hooting. Themanufacturer specified that there t race tim e s ho u ld b e fr om11-14 microseconds , and thetrace t ime shou ld be 4 9-50 m i­c rosecon ds. Th o s e r e c o m­mended duty cycles s hould beobserved when troubleshooting.

T he ti me-du ratio n m easure­men t of th e re trace pulse shou ldbe made between the 10 % levels

an amplit u de reaching 150 0 voltspeak-to-peak . The nois e cou ldcause sympto ms from drive lin esin the video picture to faint noisethroughout the TV's circuits.

First measure the DC voltagelevel of the horizontal waveform.In Figs. 1 and 2 you can see thatthe digit al display shows approx­imately 118 VDC, which is theregulated B + voltage. Next mea­su re the peak-to-peak voltage ofthe waveform. As you can seefrom Fig. 3 , the di splay shows905 volts peak-to-peak.

The frequency of the waveformmus t also be measured. That's ass im ple as pushing a bu tton on adigital scope . Figure 4 s hows the

FIG. 3-THE PEAK·TO-PEAK vo ltage ofthe waveform should be between 900 and1500 volts peak-to-peak. It's shown hereas 905 volts peak-to-peak.

FO CUS

MODEL SC61

u·"'.....'_c

SEI'JC::OF<E

~=--- •

I

- : ~ . •• I

t ransformer (lHVT) core, or openor shorted IHVT windings . Fig­ure 2 shows a n exam ple of afaulty horizontal output. Makesure the waveform looks good be­fore you proceed.

Check to see if there are anyn oi s e puls es du ring the t racetime. Many of th e noise pulsesmay not b e detected when view­ing the low-level horizontal wave­for ms, but t hey b ecome verynoticeable at the collector w i th

FIG.1-THE WAVESHAPE should be sym­metrical during the pulse retrace time .

(f)oZoa:f-o~ /.w FIG. 2-HERE'S AN EXAMPLE of a faulty6 horizontal output. Make sure the wave­~ form looks good before you check any­a: thing else.

62

MOST P E O P L E INVOLVED I N ELEC­

tronics, either as a hobby or aprofession, star t out by buildingsimple electronic kits . Along theway, th ey become fam ilia r withelectr ical terms like volt age, cu r­rent, resistance, power, and ener­gy, developing a "common-sense"kn owledge of them, wi thout fullyunderstanding th eir meaning.

When asked , "What is a volt ?" ,on e mi ght be temp ted to respo n dby quoting Ohm's law ; "If 1 ampflows through a l -ohm res is tor, aI- vol t po tential is d evel opedac ross it. " Tha t definition, how­ever, isn't much h elp in defininga volt because one elect r ical termis used to define another, which

Here's arefresher coursethat will help you

brush uponstandard

electric quantities.

mass is the kilogram, kg, wh ichis 1000 grams, the var iable beingeither m or M. The difference inusage is that m , with or withoutsubscript, normally denotes themass of an object. Whil e M canalso be used this way, it generallyrefe r s to very large, celes tialbodies , su ch as the earth, su n,and moon.

Mass is a measure of quantity,not to be confus ed with weight.Weight is the force due to gravity,which va r ies s ltgh tly over the su r­face of the ear t h, due to thechange in altitude relative to s ealevel. The standard kilogram is aplatinum-iridium (Pt-Ir) alloy cyl­inder at the In ternational Bureau

DALE NASSAR

( )~( )

~

leads to vicious-circle reasoning.A proper definition of electr icalquantities demands exam in in glength , tim e , m a s s , for c e,ch arge , an d s ome simple atom icphysics.

Standard unitsIn any scien ti fic field , accu rate

and reproducible measurem entsmust be possible. The results of ascientific expe r im en t must be de­scr ib ed in well-defined units.S ince the m e tri c syste m w illeven tually prevail worldwide, allderivation s h ere will be metric,alth ough British units will bem entioned occasionally, as aframe of reference.

We 'll n ow exam ine leng th,time, and mass , the basi c unitsfrom which all other quantitiesa re derived . In some cases, agiven letter may have multipleuses as a var iab le and/or a unit ,such as the letter C, wh ich isus ed as both the variable of ca­p a ci t an c e , an d t he unit ofcharge . Itali c le ttering w ill b eused when a label is used as ava r iab le , to a vo id co nfus io n .Thus , C will denote the variableof capacitance, while C will indi­ca te the cou lomb .

Th e stan da r d vari abl e for

length is 1, a lthough other varia­bles are similarly u sed , es peciallyd for di stance , s for di splace­men t, and x, y, an d z, relative to ase t of axes. The standard metricunit oflength is the meter, abb re­via ted m , equal to 39.37 inches .Th e m e t er i s d efin ed as1,650,763 .7 3 wavelengths of or­ange-red light em itted by Kryp­ton (Kr)-8 6 in elec t r ical di s­charge, a phenomenon th at ca nbe remeasured wi th great preci­s ion an d com parative ease, giventhe right equ ip me nt.

Th e s ta n da r d var iab les fortime a re t an d T, an d the stan­da rd uni t is the secon d, s . Nor­mally, t w ith n o s u bsc r ipt isconside red to be time as a run­n ing, independent variable. Bycon trast , t wi th a su bscr ipt, liketo' t I , an d so on, indicates eit he ran initial or s pecific referencet ime. The va riab le T, wi th orwithout subscr ipts, is normallyus ed in electronics to indica te ei­ther periods or specific ti mes onwaveforms. One secon d is de­fine d as 9, 192,631,770 cycles ofradiation fro m Cesiu m (Ce)-133 .C loc ks u sin g Ce - 133 f ro mHewlett-Pa ckard (HP) Corp. a retypi cally accurate to 1 ps.

The standard m etric unit of

of Standards (IBS), in S evres ,France. When an object exactlybalances the I-kg s tandard on abalance , it's said to be a I-kgmass, we igh ing about 2.211bs onea rth. The British equ ivalen t ofthe kilogram is the s lug, where 1s lug= 14,59 kg.

The first derived quantity isforce, F. The metric unit is theNewton, N, n amed after Sir IsaacNewton. Thus , 1 N is the force (apush or pull) need ed to acceleratea I-k g mass at 1 m/ls -'), written as1 N= 1 kg X m/(S2); this nomen­clature is expla ined below. Notehow th is definition uses length,mass, an d t ime. For exam ple,su ppose you have a toy ca r with amass of 1 kg, and you move ita lo ng the s u r face of a longs mooth ta b le . Neglecting fri c­tion , no additional for ce isneed ed to keep the ca r moving atits present velocity, the va r iablefor wh ich is v.

However, to accelerate or d e­ce lerate an object m e an s tochange its ve loc ity, whether in

"'T1magnitude (speed) or direction. HJTo do so always requires a force, JJ

even in space, in the abse nce of ~gravity. If the ca r uniformly accel- ~erates at 1 m/s per second, that (0

means its speed increases by an (0

63

Quantity Variable(s) and Unit (MKS unless Dimensionaldefining equations otherwise noted) Equivalents

Length (dis- 1,d,s,x,y,z meter (m) mtance or dis-placement)

Time t,T second (s) s

Mass m,M kilogram (kg) kg

Velocity v m/s rn/s(magnitude isspeed)

Acce leration a (general) rn/s-' m/s2

9 (due to gravity) MKS: 9.8 m/s2

CGS : 32.2 ftls 2

Force (a push F(=m x a) Newton (N) kgxmor pul l) S2

Momentum p(=F xt) kg xm kg xm(impu lse) (=m xv) --

s s

Energy (work) W joule (J) kgxm2

S2

Charge, or q, Q, (1)0 coulomb (caul or 6.24 x 1018eelectric flux C) for charge, or

lines for electricflux

Electric V volt (V), or J/C kq x rn-'potential Cxs2

(EMF orvoltage)

Current i,1 ampere (A) Cis

Power P watt (IN), or J/s kg xm2

S3

Power dens ity S IN/m2 kg/s2

Electric field E Vim kg xmstrength (or C xs2

intensity)

Electric flux o= (llo /A 1C/m2 1C/m2

dens ity = 1A x s/m2

Magnetic field H Aim Cstrength (or - -

rn x sintensity)

additional 1 mls with each pass­ing second. The variable for ac­celeration is a, while decelerationis a negative acceleration. On ornear the earth's surface, the ac­celeration due to gravity is pre­sumed constant for practicalpurposes, and is denoted byg =9.8 m/(S2) =32.2 fU(S2) . Thus,1 kg=9.8 N on earth, and since 1kg=2.21Ibs, then 9 .8 N =2.21lbs, or 1 N = 0.225 lb.

A concept that's very closely re­lated to force is momentum (p),also known as impulse and is theproduct of mass times velocity.Momen tum is defined byp =m xv=Fx t. Momentum, likevelocity, acceleration, and force,is a vector quantity, in that it hasboth a magnitude and a direc­tion, whereas energy (whetherkinetic or potential) is a scaler,possessing only a magnitude.

Throughout this article, we'lldiscuss several other derivedunits, all of which are listed in

.Table 1.

The discovery of electric chargeElectric charge was first re­

corded in 550 B.C . by Thales ofMiletus (Greece, c. 640-546 B.C.).He noted that if amber were rub­bed with fur, it attracted smallobjects, such as bits of cork. TheGreek word for amber is "elek­ton," the origin of "electricity. "Healso found that other objects re­acted similarly if rubbed with asuitable material. Such objects,after rubbing in this fashion,possess a net electric charge, orbecome electrified. A glass rodwill become electrified when rub­bed with silk, and a lucite or hardrubber rod will become electrifiedwhen rubbed with fur.

Both rods contain differentkinds of electric charge, shownby the simple experiment in Fig.1. If the electrified glass rod issuspended at its center by a longthin thread so that it rotates easi­ly, it's repelled by a second sim­ilarly charged glass rod nearby, asshown in Fig. I-a. If the chargedlucite rod is brought near thecharged glass rod, attraction oc-

C/)u curs, as shown in Figure I-b.~ That simple experiment illus-

~ ~~~e~~h~~:es:~t;i~~~ll~::~~~~uiu:J ilarly charged objects repel, whileo two oppositely charged objectso attract.~ One very important property of

64

charge is conservation. In anyclosed circuit involving capaci­tors, if a charge of - Qappears onone plate, an opposite charge of+ Q must correspondingly ap­pear on the other plate. In a cir­cuit that's off, the total initialdisplaced charge must be zero .For charge to be conserved, that

TABLE 1-L1ST OF PRINCIPAL

must also apply when the circuitis on. Thus, in any closed circuit,the net displaced charge must bezero, which is something that be­comes very important when dis­cussing capacitance.

The atomTo thoroughly understand elec-

Magnetic flux cPs CGS: maxwell g xcm2

= B x A C xs

MKS: kg xm21 Wb =1 V xs C xs

8= 10 maxwell

Magnetic flux B = ll-xH CGS: 9density 1 gauss (G) C xs

= 1 maxwell/erne

MKS: ~1 tesla (T) C xs

= 1 Wb /m2

= 1 V x s/m2= 1 N/(A Xm)

4= 10 G

Current J =I/A, C Cdensity = ~ x E

- - --m2xs m2xs

Resistance R= VII n, VIA kg xm2=p x l SX C2

A

Conductance G =1 /R siemen (S), NV SXC2[formerly the mho - - -

(n )]kg xm2

Resistivity p n xm kg xm3

= R x A SXC2- -I

Conductivity 2: S/m SXC 2= 1/p ---

kg xm3

Permitivity € F/m C2XS2- --kg xm3

Permeability Il- Him kg xmC2

Capacitance C farad (F), C2XS2= q/V, CN or ---

= T/R, S xskg xm2

= € x A)/d

Inductance L=T X R, henry (H), kg xm2= Il- x N2xA !l x s C2

I

AND DERIVED QUANTITIES

tricity requires unders tandingmatter. All matter is co mposed ofone or more elements that can 'tbe chemically decomposed anyfurther, like gold (Au), alu min u m(Al), and s ilico n (Si). The s malles tcomplete su bdivis ion of an ele­ment is the atom , as shown inFig. 2, with an extremely dense

cen tral nucleus, containing oneor more posi ti vely charged pro­tons , and neutral particles calledneutrons, and one or more n ega­tively charged electrons, equal tothe number of protons .

The atom in Fig. 2 is lithium(Ll), the third simplest atom. Nor­mally, Li has three electrons or-

biting a nucleus with threeprotons and three n eutrons. Theelectrons are much lighter thanthe protons and neutrons , an dorbit the nucleus at very highspeed . If electron orbits weredrawn to scale relative to the nu­cleus, they'd go way off the page.

Allelectr ic charge is quantized,or c o m p os e d of packets ofcharge . The magnitude of chargedepends on the number of elec­trons extra or absent. A s ingleelectron is the s mallest unit ofcharge , usually denoted "e" , andth e magnitudes of a ll othercha rge s are then integer multi­ples of e.

The charge on an electron isdefined as negative, while that ona proton is positive. However, thecharges are identical in magni­tude.

Normally, unionized atomshave as many electrons as they doprotons. The opposite chargescancel, leaving no net charge.Electrons have particular orbitsabout a nucleus; the closer theirorbit is to a nucleus, the tighterthey're held . The outer electronsare easily removed by fr iction orlight, leaving the atom with a netpositive charge, since it wou ldthen contain more protons thanelectrons. An atom may also ga inextra electrons, leaving it with anet negative charge; that's whyrubbing an object produces netsurface charge.

When lu cite is rubbed with fur,electrons are transferred fromthe fur to the rod s ince they'remore loosely bound to the furthan the rod, leav ing the rod withexcess electrons and a net nega­tive ch a r ge (the fur becomespositively charged). When glass isrubbed with silk, electrons aretransferred from the glass to thesilk (they're more loosely boundto the glass than the silk), leavingthe glas s with a net positivech a rge .

Electric field and Coulomb's lawElectric energy, which acts in a

space surrounding an ele ctricch a rge or cha rged body is call ed"lines of for ce. " Figu res 3-a and 3­b show the lines of force of Iso-

"Tllated positive and negative mOJch a rge s, respectively Figures 3-c JJ

an d 3-d show the force field pro- §;duced by two like charges and ~

two unlike charges, respectively. ~

The arrows in the diagrams rep- <D

65

Dimensiona lEquivalents

Unit (MKS unlessotherwise noted)

Variable(s) anddefining equations

Quantity

---- --

QUARTZFIBER

COUNTERr----+- WEIGHT

Electric current and the ampereSince conductors contain rela­

tively mobile electrons, many arealways in motion even in the ab­sence of electric field due to ran­dom thermal vibration . Such

tive ly, of 9 x 109 N.The magnitude of the electron

charge e was first measured in1909 by Robert Andrews Millikan(USA, c. 1868-1953). Measuringthe charges on charged dropletsof oil suspended against gravityin an electric field, he found thatall charges are in teger multiplesof 1.6 x 10-19 C/electron, or6.25 x lOIS electrons/C.

As stated above , a charged par­ticle in an electric field is subjectto a force. Ifelectrons aren't tight­ly bound, as in the outer orbits ofmetal atoms, they actually move;such materials are conductors .Materials where essentially nocharges are free to move are non­conductors , or insulators. Dif­fer en t types of materials havedifferent degrees of conductivity.The unit of conductivity is theSiemen (a), which is the re­ciprocal of resistance, which wewill discuss shortly.

CHARGED PITHBALLS

INSULATEDRODS

FIG. 3-THESE ARE " LINES OF FORCE" DIAGRAMS, (a) and (b) are isol ated posit ive andnegative charges, (c) and (d) are two like charges and two unlike charges, respectivel y.

SCALE ANDPOINTER

TORSIONSCREW

pa irs of charged objects; a basicversion is shown in Fig. 4. Theforce between the charge d balls isde te rmined from t he torsion(twi s t) in the quartz fiber.

Cou lomb found that the force,F, between charges QI and Q2 isd irectly proportional to theirprod u ct , and in vers ely propor­tional to the square of their sepa­ration, R. That re lationship iskn own as Coulomb's law, and isexpressed as F = k(QI x Q2)1(R2),where k is the Coulomb propor­tio nality constant, which de­pe nds on the medium. Cou ­lomb's Law is only valid for Rmuch greater than the radii of QIand Q2' The u n its ofF are in New­tons , N, while R is in meters , m.The signs of QI and Q2 depend onthe type of net charge , whether +or -

The u n it of charge is the cou­lomb , C. In a vacuum, k = 9 X 109

(N x m 2)/C2; the value in air isslightly higher. If QI = Q2 = 1 C,and R = 1 m, then F=9 x 109 N.Thus, 1 C is the charge, thatwhen in vacuum 1 m from a sim­ilar charge of identical or op­posite sign, yields either arepulsion or attraction, respee-

GLASS ROD

LUCITE ROD

.... ..;. + + +- _.-)+

+ + + + ..;.

FIG.1-THIS EXPERIMENT illustrates theacquisition of electrostatic charge. Theglass rods in (a) are both positivelycharged. If one is suspended at its centerby a long th in thread so it rotates easily, itwill be repelled by a second one broughtnearby. If a negatively charged lucite rodis brought near the positive glass rod , at­traction occurs, as show n in (b).

~ + + - C"" -...~~~t.... - - - -

+ - + »GLASSROD + -+~+~

b

resent the direction of force on apo sitive charge , an d the fi eldlines emanate from the charge inall directions . The relative de nsi­ty of the field lines is p ropor tion alto the field s tre ngth .

In 17 85 , Ch arles Augus t inCoulomb (Fran ce, c. 1736-1806)used a torsion b alance to performdelicate ex per iments to lea r na bou t electr ic forces b etween

NUCLEUS(/) (PROTONSAND NEUTRONS)oZ FIG. 2-THE SMALLEST complete sub­~ division of an element is the ato m, aso shown here for lithium (Li). The electron s~ are much lighter t han the protons andw neutrons, and orbit the nucleus at high6 speed. If electron orb its were drawn toCi scale relative to the nuc leus, they'd go-ca: way off the page.

66

FIG. 4-IN 17;85, CHARLES AUGUSTIN COULOMB used a to rsion balance like this tomeasure elec trostatic forces between pairs of charged objects by measuring the torque(twist) in the quartz fiber, to determine the proportionality constant. The force F betweenthem is directly proportional to their product of their charges, and inversely proportionalto the square of the ir separation R.

Resistance and Ohm 's lawWhen current flows in a con -

For exam ple, if a force of 5 New­tons is required to push an ob­j ec t , a n d that object moves adi stance of 3 meters in the direc­tion of the applied force . then 15joules of wo rk is p erformed .Whatever pushed the object ob­viously had to have th e initial en ­ergy to do so.

The concept of work an d poten­tial difference can be illustratedby exam in ing the basic op erationof a battery. Two terminals of abattery con s ist of two unlikecharges (+ and -) that maintaina constan t potential difference bychemical means . Because of thedifference in charge, an electricfield must exist between them.That electr ic field has the ab ilityto do work on an electr ic charge.For instance , if you wanted tomove a positive cha rge from th enegative battery terminal to thepositive, you would have to workagainst the electric field betweenthe te rm inals. A greater po tentialdifference between battery termi­nals cre a tes a higher electricfield . an d therefore. it s tands toreason that greater work must bedone in order to move a cha rgeagainst it.

We have now come to the unitof potential difference, which isdefined as the number of joulesper coulomb (J/C) , or work percharge. This unit is called, as youmight have guessed, the volt (V),and was named afte r AlessandroGu is eppe Antonio AnastasioVolta (Italy, c. 1745-1827). For ex­ample. in a 12-volt battery, 12 J ofenergy are n eeded to move 1 Cfrom one terminal to the other;and 24 J would be needed tomove 2 C. since 24 J /2 C = 12volts. The terms voltage, poten­ti a l difference, a n d EMF areequ iva lent , an d are very oftenused in terchangeably.

"T1mco:0c»

FIG. 5-A DEPICTION OF rando m thermal ~motion in (8), vers us a nonzero drift ve- <0

locity in (b). ~

d

A volt by any other n ame ...The defin it ion of potential. or

electro motive force (E MF) in­volves the concepts of work andenergy. Energy is the ability to dowork. Work results in motion ofan object, and is defined as theproduct of the forc e applied to anobject and th e distance throughwhich it travels . The unit of workis therefore the Newton-meter (N­m). The unit of work, or one New­ton-meter, is called a joule, abbre­viated J, after James PrescottJoule (E n gla n d , c. 18 14-1889).

Many people incorrectly as­sume that electric current flowsat an extremely high speed. whenit literally moves at a snails pace!It is the electric field that movesdown the conductor at very h ighspeeds. It can be mathematicallyshown that if several amps of cu r­rent (ei t h e r AC or DC ) flowsthrough standard h ous eh oldcopper wire, the dr ift velocity ofthe electrons move on ly a fractionof a millimeter pe r second , butthose slowly cre ep in g elect ronsproduce considerable h eat due tofri ction . in the wire.

c

motion is fairly rapid, with an in ­stantaneous velocity of about 105

mls. Electrons undergoing suchmotion in the absence of an elec­tric field follow an er ratic zig-zagpath, rema in ing in the same lo­calized region, as shown in Fig.5-a.

When an electric field is appliedto a conductor, the erratica llymoving electrons drift due to theforce generated by the field. caus­ing an electric current, as sh ownin Fig . 5-b . Drift velocity is muchlower than instantaneous ve­locity ; about 1mmls compared to105 mls for the instantaneous ve­locity when no elect r ic field ispresent.

The variable for current is ei­ther i or I, for AC and DC cu r ren t .respectively. The unit of currentis the ampere, abbreviated eitheramp or A, after Andre Marie Am­pere (France. c. 1775-1836) . Bydefinition 1 A = 1 Cis , indep en­dent of conductor area; the sym­bol A is used for the amp, asdistinguished from A for area . If 1A flows in a wire. then 6.25 x 1018

electrons pass through a cross­section of it every second.

67

ba

v

+v1- +v2- +v3-

+q -q +q - q +q -q

C~::J1::__++1 -+ ..-=-----+1.-=-----+1 -

C1 C2 C3

+ -

Va

V=V1+V2+ V3+q - q

+ -.-- --,+ ­

1/C1= lIC1+1/C2+1/C3

Inductors and inductanceT he in ducto r consists of a

length of wire wound into a sole­noidal or toroidal shape, with orwithou t a center core as shown inFig . 9 . When cu rrent passesthrough the coil, magnetic fluxlines are establis hed, as shownin Fig. 10 . Inductance (L)of a coilis it s ability to store energy in the

+

+V-b

FIG. 8-SERIES CAPACITANCEScombinelike parallel resistors (a). The reciprocal ofthe total capacitance 1/CT = 1/Cl +1/C2 +1/C3 (b). (See text for the derivation.)

FIG. 7-PARALLEL CAPACITANCES com­bine like series resistors (a). The total ca­pacitance CT = Cl + C2+ C3 (b). (See textfor the derivation.)

soning is easily extended to anynumber of parallel capacitors.

To combine capacitances in se­ries, consider C1 an d C2 in seriesacross battery B1 of.voltage V, asshown in Fig. 8-a. To find CT ' asshown in Fig. 8-b , you can seethat V=V1+V2' an d since thetotal charge arou n d the circuit iszero, Q1= Q2 = Q. Therefore , Q/C T = ( Q / C1) + ( Q 2/ C 2) = ( Q /C1) + (Q/C2). Canceling Q givesl/CT= (lIC1)+ (lIC2).

C=QN

where capaci tance is in uni ts offarads (F), named after MichaelFaraday (Great Britain, c.1791-1867).

If a capacitor is rated at 1 F,then 1 C of charge ca n be main­tained on the plates when there's1 volt between them. One farad,of cou rse, is an extremely largeca pacitan ce; most practical ca ­pacitors have values on the orderof microfarads (f.1F) or picofarads(pF). Ideally, assuming there is nolea ka g e current between t heplates through the dielectric, thecharge on the plates can remainintact indefin itely, although suchleakage always occurs in actualpractice.

The factors that affect the ca­pacitance of a capacitor can beseen in the equ a tion

C =EOXEr xNd

where EO is the permittivity of ai r(8.85 x 10- 12 F/m), Er is the rela­tive permi t tivity; A is the area ofeach plate in square meters and dis the d is tan ce between the platesin meters.

The p receding equation revealsthat capacitance will increasewith a la rger plate a rea, or whenthe distance between the platesdecreases. The permittivity fac­tor E is a measure of how well agiven dielectric allows electricfield lines to be established be­tween the p lates . When an in­sulator is used between thep lates , the ca pac itan ce will in­creas e by a factor of Er . The Erfactor equals E/E o' which is betterknown as the dielectric constant,k. As a point of in teres t, the rela­tive permittivity E r of air is1.0006, rubber is 3 .0 and that ofwater is 80.0 .

You're probably aware that ca­pacitances in paralle l add . Toshow this, conside r C1 and C2 inparallel across battery B1 of volt­age V, as shown in Fig. 7-a . Thetotal capacitance CT ' as shown inFig. 7-b, can be found by the fol­lowing analysis . If Q1 and Q2 arethe charges on C1 and C2 , thenQT=Q 1+ Q2' Since the voltageacross both C1 and C2 is V. thenQ1= C1 x V, Q2= C2 x V. There­fore, QT=(C1 xV)+(C2 XV)=(C1 + C2) x v. Dividing by V givesus Q~=C1+C2, bu t CT=Q~s o CT = C1 + C2 . Th e same rea-

across its plates . Capacitance isdefined as

C(FARADS)=QNc

----...". +

Capacitors and capacitanceA capacitor is basically two

con d ucting surfaces separatedby a dielect ri c , or insulator, asshown in Fig . 6 . The capacitanceof an element is its ability to storeelectr ic charge on its plates. Thelarger the capacitance (C), themore charge (Q) will be stored onits plates for the same voltage (V)

ductor due to an electric field ,electrons gain energy because oftheir motion, called kinetic ener­gy. As they move, they collide withatoms of the conductor, dissipat­ing kinetic energy as heat. Theconductor can be said to have adegree of resistance to the flow ofelectr ic current.

Geo rg Simon Ohm (Germany,c. 1787-1854) , for whom the unitof res istance, the ohm (il) isn amed , showed that cu r r en tflowing in a conductor is directlyproportional to the voltage acrossit. That concept may be apparentto you since we know that a high­er voltage produces a strongerelec tr ic field, and therefore exe rtsa greater electr ic force on the

. charges of the conductor. Thatrelationsh ip is known as' Ohm'slaw, and can be written as V= IR,where V is the voltage across theconductor, I is the current in am­peres through t he con du ctor,and R is the proportionality con­stant, which is a direct measureof the electrical resistance of theconducto r. If the equation issolved for R, we get R = VII. Theunit R, therefore, is in volUampsand is called an ohm (il). Ohm'slaw states that if a current of oneampere flows through a conduc­tor when a potential of one volt isplaced across it, the conductor issaid to have a resistance of oneohm.

"/~: v,/ / //

/ / /""///// -

/////"/ / / /11

/ / / /

\~;::g;;i::;l~g;:i=j;;~/ ~J~:1:

:: ~ ~ =~ =~ :: =~ DIELECTRIC

~ - - -- ----r ; LECTRICFIELD

o (8a:o FIG. 6-A CAPACITOR consists of tw ow conducting plates separated by a di ­m electric, or insulat ing material. When theo plates are charged , an electri c field is es-o tablished between th em. Capacitance~ (F) =QIV.

68

a

A

-'­J.I,(CORE)

MAGNETICFLUX LINES

1/:11,\" \\ \\ \I \, tt II II I, ,I I

/ JI I

,-./ /\ ,/'-~

/"-',,I ,._....I I, II I

i :I t

INDUCTANCE !I (L)I \\ II \\ \\ \\ \\ '-\ I, /

<,-~IL ~

FIG. 1Q.-AN INDUCTOR CONSISTS of acoil of wire wound around a core of air orferromagnet ic materia l. When currentgoes through a coil, magnetic f lux linesare estab lished.

Some additional pointsMany interes ting an d impor­

tan t d eriva ti ons can b e m adefrom the concep ts discussed inth is article . We'll take a look at afew examples of some commonlyused electr ical terms.

All t imers use time constan ts,whether capacit ive (RC ) or in­ductive (RL). For an RC t ime con­stan t. the units a re T = R x C =n 'F= (VIA) x (CN) = C/ A = C/ (C Is) = s . Therefore, the units of anRC time constan t are in secon ds.

A cou ple of a dditional, morep racti cal units for both chargea n d energy are t he am p -h ou r(Ah) a n d th e kil owatt-hou r(kWh). A 1-Ah rating is found onmany b atteries . If a battery israted at 4 Ah , it can su pply 4 A forone h our. or 1 A for 4 h ou rs , or0 .5 A for 8 h ours . an d so on.S ince 1 A = 1 Cis . an d 1 hr =3 .6 x 103 s. then 1 Ah = 3.6 x 103C:

The exact charge obtainab lefro m a ba ttery depends on thecu rrent drain. u sually decreas ­ing as cu r ren t drain increases . ."due to h eating. Electric u tili ti es rnd etermine bills from the kWh JJ

Cyo u r h ou s e cons u mes eve ry :J>

month. S ince 1kW= 103W, 1hr = ~3 .6 x 103 s, and 1 W = 1 J /s. then 1 (0

kWh = 3 .6 X10 6 J . R-E ~

cou rse, s ince the atmosphere ab­so rbs a considerable amount ofth is energy, you n ever actu a llyfeel a ll t h a t power. Similarly, a100-W light bulb lit erally radiates100 J /s , but becomes dimmer thefu rther you get from it becausethe power is d is sipa ted over awide r a rea.

Power and the wattPower is a measure of the time

rate of either expen ditu re or stor­age of energy, whether electr ical,the r m a l, or a ny other form .Power, therefore has units ofwork per time, an d is measuredin J /s , called a watt (W) , namedafte r J ames Watt (Scotland , c .1736-1819). To derive the defini­tion of a watt , we must th in k interms of the rate a t which work isbe ing done on electrical charges.Since 1 A= 1 Cis , and 1 W= 1 J /s ,the n t he proportionali ty co n ­stant must have units of J /C, orvoltage . Therefore, P = E x I, andsince Ohm's Law ~ives E = I x R,then P = J2 x R= (E )/R.

Power is directly related to elec­tric an d magneti c field quanti ti esmentioned ea rlier. If you take theproduct of electr ic and magneticfield s trengths E and H , then (VIm) x (Nm) = (V x A)/(m 2 ) =W/(m 2 ).

This is power per unit area , alsoknown as power density, an d isgenerally denoted by S .

In electromagnetic waves , theelec tr ic field s tre ngth E an d mag­netic field strength H vectors areperpendi cular t o one a nother.You can 't s imply take the a rit h ­metic product of the magnitudesof the vectors at a given point toob tain the power density.

For exam p le, the s ola r co n­s tant, or the mean power den si tyreaching the ea rth outside its at­mosphere, at n ormal incidence,an d at a mean orbital radius fromthe sun, is about 0 .14 W/cm2 . Of

rial compared to a ir. As the mag­n etic properties of a m aterialincrease, so do es its relative per­meability. So me materials , suchas steel a n d iron, h a ve p er­meabilities that a re hundreds orth ousands of times hi gher thana ir, or fLr ;:::lOO. A coil with no coreh a s a p ermeability fa ctor offLr = 1. The inductance can be in ­creased by placing a core with ahigh permeability, such as a fer­romagnetic material , within thecoil.

Our discussion now leads us toseries a n d parallel inductors .The total inductance for induc­tors in series ca n be determinedthe same way as ser ies resistors;L,-=L J +L2 +L3 + ... + Ln . For in­ductors in parallel , the total in­ductance can be found the sameway as for parall el r esistors ;lILT = l /L, + lIL2 + lIL3 + .. . + l ILN ·

J,l,(CORE)

fL = fLr x flo

where fLo is the permeability ofai r (4 x Jt x 10- 7 HIm) an d fLr is therelative permeability of the mate-

TI

FIG . 9-TWO TYPICAL COIL con­structions are the solenoid (a) and thetoroid (b). Inductance in henrys (L) is de­fined as L = N2x flAil.

form of a magnetic field . The unitof inductance is the henry. Oneh enry is the a m ou n t of induc­tance n ecessary to produce 1 voltac ross a coil with a cu rren t thatchanges at a rate of 1 am pe re persecond, an d is exp ressed mathe­mati cally as

L= E/(dl/dt)

where E is the induced voltageand dIldt is the rate of currentchange in amperes per second.

For mos t applications, 1 h enryis a very large unit of inductance.Indu ctance is u sually specified inunits of millihenrys (mH), m icro ­h enrys (fLH) or nanohenrys (nH).

Induc tance can al s o b e ex­pressed by the equation

L = N2 x J.!AIJ

where N is the number of turns ofwire, A is the core area in squaremeters, 1 is the co re length inmeters , and parameter fL is thepermeability of the material. Thepermeabili ty of a ma terial is ameasure of its magneti c proper­ti es, and is determined by theequati on

69

NEGATIVE ION GENERATOR

contin uedjrom page 60

the needle directly. When poweris removed, the rotor sp ins untilthe capacitors co m pletely d is­charge. Before removing the ro­to r, turn t he power off, a nddischarge any remaining voltageacross the ca pacitors .

A s im ple experime nt ca n showhow n egative ions t rave l to an earby insulated obj ec t , charg­ing it to hi gh voltage . With thepower on, the n egative ions travelthrough the a ir, an d in doing so,collect on any metal su rface . Youcan s how how that works with anem p ty can a s a collector, a sshown in Fig. 11.

Rest the can on an insulatedsurface, s uch as a rubber mat, sothe charge won't leak off. Use anear t h grou n d for discharging,such as a n AC outlet gro u n dscre w or a wa ter pipe. As thenegative ions hit the can, chargebuilds until the ca n is charge d to90-100 volts DC, NE2 fires, andthe process repeats as long as then ega tive ion g enerator runs.Start wit h the can 1-2 feet away;you will notice how the flash rateof NE2 increas es as the dis tancebetween the n egative ion gene r­ator and the collector decreases ,or if the em itter needle points to­ward the ca n .

Both expe r im en ts can run s i­multaneously; as the ion mo torrotates , dissipating charge intothe a ir, the can collects the nega­tive ions and flashes the n eonbulb. Another experimen t uses a40-watt fluorescent tube in a verydark room; be very ca refu l whileh andlin g th e gl a s s tub e indarkness-they 're very fr agileand you could hurt you rself if oneimplodes.

Connect a grou n d wire to a ter­minal at one en d . Hold the tubenear the grou n de d end withouttouching metal. Bring the ot he rend toward the n egative ion gen­erator with out touching it. Thetube shou ld flash or glow, indi­cating the presence of negative

~ ions. As you move the tu be away,~ bo th the flash r ate and g lowa: s ho u ld decrea s e. Wh en yo u 'reG fini shed with the n egative ionwuJ generator, tu rn it off, di schargeo it , a nd be su re to cover the emit-o ter needl e with the cork or other[!f type of in sulator. R-E

70

HOT TROUBLESHOOTING

continuedjrom page 62

rate digi tal readings when it isunsealed.)

Select the dual-channel mode,cou ple chan nel B to grou nd, andalign the trace so it lies on the10% gra ticu le ma rking. S electthe t ime-measu re men t mode ,an d set the "begin" an d "end"knobs s o that the intensifi edtrace section is as s hown in Fig.5. The digital display s h ou ldsh ow between 11 and 14 microse­con ds . (The displ ay in Fig. 5shows 12.83 mi croseconds .)

If you measure, say, 9 mi crose­conds , instead of 11-14 microse­conds, even though the peak-to­peak value, the DC voltage, thewave shape, and the frequencyare correct, the TV will work forawhile, but will more than lik elyfail a t some po int. That's becaus ethe horizontal ou tput sys temsees a 35 .7 % reduction in retracet ime-meaning tha t retrace isfas ter and generates hi gher volt­age . Therefore , the h orizontaloutpu t transistor is on lon ger a tfull-s can con duction, producingin creased heat, increased scan­derived power su pply levels, andhi gher voltages throughout these t. All th e c i rc u i ts a re nows t ressed working at the highervoltages. That, in time, will causecom ponen ts to fa il.

Your scope can also be used towatch for an instantaneousstart-up pulse. Simply connectthe scope and preset it to view theHOT pulse. Then, watch the CRTas you apply power to the TV'scirc u it ry. Ifyou see a pulse appea rand th en disappear, your s tar t­up circuitry is operating an d theset is in the shut-down mode.

If t hat h appens , serv ice thechass is in a "p owe re d -d own "con d it ion by either halving thenormal B + level separately, or re­ducing the AC input power to60- 90 VAC. Then monitor thecollector of the horizontal outputtran s is tor with you r scope .

Many underlying performanceproblems can be uncovered by ex­am in ing s pecific ch a racter is t icsof the "HOT puls e. " The wav e­form shape, symmetry, and dutycycle of horizontal output tran­s is tor is critical in di agnosinga n d troubleshooting elect r ica lmalfunctions in your TV set. R-E

SWEEP/MARKER

continued j rom page 49

RDD104 IC's made by LSI Com­puter Systems, In c . A 5-MHzcrystal oscillator used by IC17 isprogram med via p ins 1 and 2 todivid e by 1000. Its ou tpu t at pin 7is fed to the input of IC18 whichdivides by either 1,000 or 10,000,depending on the position of theSIN E RANGE switch . The output isa square wave and provides ei­ther 0 .1 secon d or 1.0 secondsampling of the. frequ en cy to bemeasured by the s hor ting or non­shorting action of transistor Q8.The s ame precision square waveis differentiated by C61 and R73to originate a positive updatingspike at pin 5 of the counter chip,IC19 . The same s quare wave isintegrated by C60 and R74 to pro­vid e a reset voltage a few millise­conds a fte r th e update . TheRDD104 IC needs about 12 voltsto os cilla te at 5 MHz, and sincethe counter IC requires 5 volt s,dual- voltage s u p plies are reallyn ecessary.

The s chematic of the peak-holdcircuit is shown in Fig. 9 . In thatcircuit, op -amp IC2 3 amplifiesthe si gnal from the device undertest about four times.

The positive alte rnation of thewaveform is squ a red and inver­ted by op-amp IC26 . That near­square wav e is a pplied to thebases of transis tors Q13 andQ14, both of which act as switch­es and behave as either open cir­cuits or shorts to ground. If Q14is a 2N2219 transistor, it shortsto within 5 millivolts with refer­ence to grou n d. If a VN0300Mpower MOSFET is used, it shortsto wi thin 1 millivolt to ground.

When Q13 and Q14 act as opencirc u its , C93 ch a rges to the peakvalue of the positive alte rnat ion ,following the rising edge of thealte rnation an d then holding thepeak value because there is nodi s charg e path. The fla t-topportion of that charge is one seg­ment of the positive contour line.Transi s tor Q13 discharges C93,and the n ext t ime it a cts as as hort ci rc u it. Th is va ry ing b e­tween charge -time and short-cir­cu i t time conti n ues for eac hcycle.

We're go ing to have to stop atth is point. Next month we 'll buildand test out the unit. R-E

DON LANCASTER

HARDWARE HACKERThis month we'll talk about cheap visible lasers, electric motor

resources, induction motor controls, new wavelet math theory, and adual digital potentiometer.

Let 's start off th is month's co l­umn with a very hackablecircuit opportunity that has not

quite seen the light of day. At least notyet...

Ind uction motor speedcontrols

Why sho uld it be cheap, easy, andtrivial to regulate the speed of yourelectric dri ll, yet super expensive andnext to impossible to contro l thespeed of a compressor or blowermotor on an air condit ioner? After all,a motor is a motor, isn't it?

Sadly, the answer is no. Those ACinduction motors simply were neverdesigned to have their speedchanged , and they throw all sorts ofreally ugly hassles at you when youtry to do so . Let's see why that's so.

Just about all electric motors arebased on two fundamenta l electricalprinciples. The first of those is thatlike magnetic poles repel and op­posite ones attract. The second isknown as Flem ing 's Rule , whichstates that " a curre nt carrying con­ductor at right angles to a magneticfie ld will produce a force and attemptto move in a directio n at right anglesto bot h the magnetic field and thecurrent. "

When using conventional current,that produces the familiar right-handgenerator rule, wherein your thumbpoints in the direction of the motion,your index finger towards the southpole of the magnetic fie ld, and yourmidd le finger in the direction of theconventional current.

For a motor, the same rule appliesto your left hand. The only theoreticaldifference between a motor and agenerator is that you input motion toget an output current with the gener­ator, while you input current to get aforce and hopefully a motion with amotor. In reality, all motors do somegenerat ing, and vice versa .

So , your only trick to building amotor is to constantly rearrange yourmagnetic fields and their strengths sothey are either att rac t ing one another

or shov ing each other away, or usesome ongoing combination ofattraction and repulsion together.

A motor usually consists of a sta­tionary part called a stator and a mov­ing part known as a rotor, orarmature. If it's necessary to phys­ically t ransfer current to your rotor,either brushes and a commuta tor, orelse slip rings are used. Slip ringsapply continuous power to your rotor,wh ile fixed brushes and a com ­mutator selectively switch in and outchosen windings that happen to bealigned with the brush axis at anyparticular point in time .

You'll find quite a few different pos­sible motor designs. But by far thetwo most economically important arethe series D C motor with brushes,which is sometimes called a universalmotor, and the AC induction motor.Let's take a look at each one .

Figure 1 shows a universal motorand its torque versus speed curve .You' ll recognize this one in your elec­tric dri ll , hot tub blower, vacuumcleaner, blender, sew ing machine, orolder car starter.

There's a pair of wo und stator coi lsthat, when run on DC, wi ll produce aconstant statio nary magnetic field. Inseries with the stator coi l is a pair ofbrushes w ith a commutator, whichselectively switch rotor windings inand out so that one or more wind ingsis constantly getting attracted to thefixed stator field . As the armature ro­tates, new windings get switched inby the commutator, so that a more orless continuous attraction, and thus arotary motion gets produced.

The same universal motor works

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Don LancasterSynergeticsBox 809Thatcher, AZ 85552(602) 428-4073

almost as wel l w ith AC , except some ­times you have strong fields andsometimes weak ones as the currentalternates. Usua lly, the mec hanica linertia of your load wi ll more or lessaverage all those variations into con­t inuous rotary power.

Even with AC , you sti ll always haveop posite po les attracti ng one an­other. They just happen to changetheir polar ity 120 times a second. Butthey always change together. Notethat you can reverse your universalmotor by placing a DPDT switch be­tween the commutator and the statorcoils . But that can cause excessivewear if the motor brushes were notdesigned for two-way use.

As your universal motor slowsdown , its torque will increase, whichtends to add to the motor stability. Asyou slow down , the available "twist"increases to speed you back up, andvice versa.

Since you have lots of torque atzero speed, your motor self-starts . Itmay overheat if you stall it perma­nently, but given half a chance, a uni­versa l motor easily gets itself up tospeed .

Any motor is simultaneous ly a gen­era tor, and vice versa . A universalmotor that is lightly loaded and run­ning at a high speed produces an out­put voltage and resultant current inseries with your input current. Thevoltage that is generated is known asa back emf, which opposes the inputcurrent. When lightly loaded, very lit­t le current is drawn from the supply,since the back emf and its resultantcurrent nearly cancels out the inputcurrent, whic h is real handy from aconservation of energy standpoint. Ifyou're doing no useful work, and ifyour motor isn't getting particu larlyhot, then you shouldn't need toomuch input energy just to spin things.

As you add mechanical load, your ~

series machine wi ll become less of a ~

generator and more of a motor. The ~

back emf and its canceling current ~

drops, and the input cur rent goes up. <0Your new energy needed is mostly ~

71

STATOR

I

TORQUE ROTOR ~ TORQUE I

ISTATOR ~ !

SPEED SPEED

STATOR

ROTOR

STATOR

FIG. 1-A UNIVERSAL SERIES motor with brushes used on anelectric dr ill , along with its speed-torque characteristics. Thespeed of the motors can be easily electronically controlled byusing simple circuits.

FIG. 2-A SYNCHRONOUS AC MOTOR used on a clock, alongwith its speed- torque characterist ics. The speed is determi nedby the line frequency. The input current determines how strong aload can be driven.

transferred to your mechanica l load.Aga in by conservation of energy,you 're putting more energy in so youcan get more energy out.

Neg lecting nonlinearities such asair resistance, the speed of a univer­sal motor for a given load is deter­mined only by the input curre nt. Youraise your current to go faster; reduce

. it to slow down . That means you canjust throw any old high power resistorin series with your universalmotor tocontrol its speed, just like sewing ma­chine motors used to use. Better yet,you can use a far more efficient triacsty le light dimmer for control.

Best of all, you can sense the backemf or otherwise measure the actua lmotor speed and use electronic feed­back with a triac or SCR circuit whichis only sl ight ly more comp lex than aplain old dimmer. That gives you atight ly regulated speed contro l plusthe ability to run real slow with lots oftorque.

The bottom line is that it's tr ivialthese days to electronically regulatethe speed of a universa l motor. We 'veseen severa l circu its in past issuesand in those Hardware Hacker /I re­prints. LSI Systems is a good sourcefor fancy universa l motor controllerchips, whi le lots of deta iled applica­tion notes appear in the usual triacdata books from Motorola, 50S,Texas Ins t rum en ts , and severalothers .

~ So what's wrong with universalz motors? If they are so universa l, why~ aren't they used everywhere? TheG biggest problem lies in their brushes .~ Brushes wear out. They are ineffi ­6 cient. They are both acoustically andis electrically noisy. They spark and canCi start fires or explosions. And those

problems really get out of hand whenyou need more horsepower.

Look around, and you'll see thatvirtua lly all universa l motors in yourhome only run on an intermittentbasis. Mostly because the brushescannot run continuous ly withoutgrinding themselves into oblivion, ordriving you up the wall wit h noise .

Ideally, we wou ld like to conjure upsome scheme to get power onto therotor w ithout any brushes or otherphysica l contact. And that's wherethe induction motor comes in.

Figure 2 shows a brush less beastieknown as an AC synchronous motor.It has a wound stator and a perma­nent magnet rotor. Assume that weare plugged into the 60-Hz AC lineand that the rotor just happens toalready be spinn ing at 3600 RPM .

On a positive line peak, the northmagnet po le wi ll get attracted to theupper stator coil. By the time yourmagnet is pointing straight up, thecurrent w ill be going through zero andthere will be no mut ual attraction orrepulsion . Soon afterward, the linecurrent swings negative, and that op­pos ite polarity starts repel ling themagnet, continuing it on its merryway. The exact opposite happens tothe other pole, and the motorwill con­tinue to spin .

The synchronous speed is set onlyby the number of poles and the linefrequency, and is totally independentof your input current. The two polesynchronous motor runs at 3600RPM off the 60-Hz line; a four polejob spins at 1800 RPM, and so on.

We can see that a synchronousmotor is real handy for maintaining aconstant speed . Important uses arein e lectric c locks, phonograph

motors, timers, chart drives, andother lower power uses where an ab­solutely constant speed, indepen­dent of the load or input current, isessential.

What happens when we apply toomuch of a load? If your magnet gets90 mechanical degrees out of phase,there wi ll be no attraction or repul­sion, and zero power routed to theload. If it gets further out of phase, itactua lly tries to sta ll itse lf. Therefore,the slower the speed , the less thetorque .

You really have a two-speed devicehere: 3600 RPM and 0 RPM . Oneconsequence here is that any truesingle-phase synchronous motor willnot start by itself. You will have to helpit along w ith a sw itchable startingwinding , a po le shading, an iron hys­teresis cup, or a second or third wind­ing driven from a two -phase or three­phase source.

A second consequence is that thespeed of a synchronous motor withvarying load or current can end upunstab le. If it ever breaks out of sync,you almost sure ly will stall. That hap­pens because a slowdown producesless torque, which in turn producesless speed . Just the same as an autoin too high a gear for the grade .

The load current does decide howlarge of a load it can drive at syn­chronous speed. The more input cur­rent, the more power you can deliverto the load without having to breakyour synchronization .

Figure 3 shows a variation on asynchronous machine known as theAC induction motor. It is by far themost common motor in use today.You will find AC induction motors inyour air conditioners, heater blowers ,

72

FIG. 3-AN AC INDUCTION MOTOR used on a washing machine,along with its speed-torque characteristics. The current controlsthe speed over a very narrow range between the optimum slipspeed and the synchronous speed . To control the speed of thistype of motor over a wider range, you must use a complexcycloconverter circuit that can change both the input frequencyand current.

ANALOG ~POTENTIOMETER

OUTPUTS

SERIAL DATA CLOCK o-------- - ·I......J

SERIAL DATA IN 0>------- - - - 1-----'

DATA LATCH

FIG. 4-A DUAL DIGITAL POTENTIOMETER using the DallasSemiconductor DS1267.A 17-bit serial word determines which ofthe 256 steps for each potentiometer gets selected. UnlikeEEPOT ch ips, the settings are easily read but forgotten on power­down. A serial output lets you daisy cha in your digital com­mands.

+SV

SPEED

TORQUE

...•:.:....ROTOR

STATOR

STATOR

SYNERGETICSBox 809-RE

Thatcher, AZ 85552(602) 428-4073

have to use pulleys and belts or someother spe ed -redu ction scheme. Orgo to lots and lots of poles, as is donein those fancy ceiling fans.

Thus , any attempt to control thespeed of an induction motor with aseries resistance or a simple phasecontro l is doomed to failure. Flat out,

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speed.If you lower the speed slightly, you

create even more torqu e. But if youslow it down too far, your torquestarts dropping radically.

Thus , an AC inducti on motor hasoptimum torque at a speed which ison ly m ode stl y les s than s yn ­chronous. That' s why your "quarterhors e" motor is usually rated at 3450RPM for a two-pole motor and 1734RPM for a four-pole one .

As you can see, we have a we ll­behaved torque -speed curve be­tween the synchronous speed andthe optimum, but only a slight ly slow­er peak torque speed . Below thepeak speed, you 'll have the same in­stabi lity and dropout problem s thatyou'd have with a pure synchronousmachine .

Like a synchronous motor, a single­phase induction motor will not startitself. Usually there wil l be a secondstart ing winding that gets kicked inonly when gett ing the motor up tospeed. Other start ing variat ions caninclude a pole shading or multiplephase windings .

In theory, you could reverse yourinduction motor by reversing the di­rection the start ing method shovesthe rotor. Details vary with the motortyp e. In some cases, the only way toreverse the motor is to remove therotor and put it back in point ing theother way.

An other pro blem with inductionmotors is th at th e opt imum motorspeed is usually far too fast for usefulreal-world work. You almost always

washers , mo st t able saws , di sh­washers, dryers, dr ill presses, waterpumps, and many circulation fans.

Motor s used in thos e types ofproduct s are also the ones you wouldmost like to be able to inexpens ivelycontro l the speed of. You would es­pecially like to raise the efficiency ofheating and cooling systems.

The concept of the AC inductionmotor was positively bri lliant. Teslastrikes again. Somehow you have toget currents onto the rotor, but wedefinitely want to avoid any brushesor other mechanical contacts .

Que st ion : What do you get whenyou have coils and iron driven fromAC current? Answer (A) a motor, or(6) a transformer CD.

Inste ad of brushes or slip rings,you transformer couple the rotor cur­rent in an induction motor. That' s usu­ally don e by creating a spec ial Iow­impedance tran sformer secondaryknown as a squirrel cage. The pur­pose of the squirrel cage is to serveboth as the transform er secondaryand as rotor coil s to simulate the rotormagnet of Fig. 3 .

But not so fast. Literall y. If you'rerunning at synchro nous speed, nolines of flux will be cut, and there wi llbe no current induced into the squir­rel ca ge . Which gi ve s yo u syn­chrono us speed, but ze ro powe r.Now, let your speed slip just a littlebit. There 's now a very low-frequencyAC current indu ced in the squ irrelcage . That creates a changing mag­netic fie ld, and you now have moretorque than you do at synchronous

73

ELECTRONIC MOTORRESOURCES

en()

zoa:r­ow--lW

6is<l:a:

74

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that w ill never work and probab ly wi llburn up your motor as wel l. It's likeplowing with a pig.

Now, you can use current control.toalter the speed of your motor be­tween its synchronous speed and itsslight ly slower optimum speed . Butthat range is usually far too narrow tobe usefu l, unless you're willing to varythe frequency applied to your moto r.But since the impedance of a motorvaries with frequency, you 'll also wantto vary the voltage or the input cur­rent as you change frequency. Keep­ing the magnetic flux at a constantstrength seems like a good startingpoint. so raising the voltage with theline frequency seems like a goodidea. You' ll also have to quite accu­rate ly sense your motor speed at alltimes, ana feed back all of that infor­mation into your controller.

In addition , you do have to guaran­tee that the starting windings do notkick in at slower speeds. Most start­ing Windings are for very intermittentduty only and will rapidly burn up if runcontinuously.

Circuits which sense motor speedand vary both the frequency and thecur rent are o ft e n known ascycloconverters . Yes, you can getth em . One major suppl ier is AseaBrown Bovari, a Swiss firm with awide range of induction motor speedcontrols. But they 're not cheap. Andcycloconverter-controlled inductionmotors tend to whine a lot. owing tonon linear magnetic harmonics in theaudio range , unacceptably so formany uses .

But a $19 .95 wide range and quietquarter horse induction motor speedcontrol is not likely to show up in yourhardware store in the ne xt fewmonths. Even though we do have lotsof better magnetics and new intel­ligent-power integrated circuit s avail­able that should make the task fareasier than it once was. .

What you 're more likely to see aremod ifications of traditional induct ionmotors which can make them moreamenable to electronic speed con­trol. You' ll come across such thing sas dual stato rs , variable-frequencyrotors, and internal speed sensors .

Wh at's the bottom line? A lot atthought and time and effort has goneinto induction-motor speed contro lsfor several decades now, and nothingreally useful has yet seen the light ofday. Despite an incredibly big bag ofnickels waiting for the winner.

An Affi liate of Emerson Electric Co.

Made in the U.S.A.

B e cklTla n Indu§triar "mOJ:DC»:D-<

$149

Probe HoldN

TrueRMS

4 Digits

10,000 Counts

Relative Mode

3Yr. Warranty

Auto MinMaxN

lOA Range (fused)

0.25% Accuracy

ProtectiveHolster

41 Segment AnalogBar Graph

Beckman IndustrialRMS225

1,000 Hour BaUery Ute

Touch Hold@

$159'

3.1/2Digits

FlukeModel 77

3,200 Counts

3Yr. Warranty

0.3%Accuracy

l OA Range (fused)

ProtectiveHolster

31 Segment AnalogBar Graph

2,000 HourBattery Life

Its nofluke.

Instrumentation Products Division3883 Ruffin Road,San Diego, CA 92123-1898

(619) 495-3200• FAX (619) 268-0172 • TLX 249031OutsideCalifornia1-800-854-2708Within California 1-800-227-9781

© 1m Beckman IndustrialCorporation.Specificationssubject to changewithout notice. flukeIsa registeredtrademark01john FlukeMr~ Co. Inc.

Buildingthe best DMMfor themoney is noaccident.The newRMS225 was carefullydesigned togive you what you wanted at a prioeyou could afford. Visit your local distributortoday andyou'llagree the choioe isobvious.

@Touch Holdisaregisteredtrademarkofthe JohnFlukeMfg. Co., Inc. ' 1990 FlukeandPhilips Catalog

Dual d igital potentiometerA ways back (Hardware Hacker.

January 1989), we looked at a Xico rX9 103 digitally contro lled 100-steppotent iometer. This dude was a sin­gle-chan nel device, had a permanentmemory that remembered even whenit was unpowered, and let you incre­ment or decrement the potentiome­ter sett ing with a simple interface.But it had no way to sense the pres­ent setting, nor any way to jump toany sett ing without moving throughall of the intermediate ones.

Dallas Semicondu ctor has just in­troduced a new DS1267 dual digitalpotent iomet er c h i p that hasstrengths where the X9 103 wasweak , and v ice versa . A s Fig . 4shows us, this one gives you two256- ste p potentiometers in a singlepackage in your choice of 10K, 50K,or lOOK total resistance.

Those are not memory devices .They return you to a 50 % " mid­wiper" pos ition on power up andmust get rewrit ten each time. As isbecom ing com mon on many newchips these days, there is a three­wire serial contro l provided, intendedto interface with three computer portlines .

To set up your potent iometers ,cloc k in seventee n data bits by usingthe cue and DQ lines, while keepi ngthe RST line high. Eight of tho se bitsare for the first potentiometer, eightfor the second, with the final bit beingused to optionally cascade the poten­tiometer pair into a single potentiom­eter with 512 steps of reso lut ion.

Drop the RST line to enter the newsettings for the potentiometer pair.There's also a ser ial OUT that lets youread out the present setti ngs or elsecascade ch ips for such things asmulti-band equalizers .

As long as RST remains high, yourold set ting gets saved. Thus, you cando 17 clocks to read out your exist ingsettings, and 17 more to enter thenew ones , w ithout gett ing any noiseor glitc hes.

The digita l end of the chip works offyour usual 0 and +5 volts. The ana­log end can be anywhere from 0 to+5 volts w ith a grounded VB sub­strate pin, or can be used over a - 5to +5 volt range with - 5 volts on

As usual, be sure to send all yourwrit ten entries direct ly to me atSynergetics , rather than over to Ra­dio-Electronics edito rial.

I strongly urge you to try and hackthis one. But don't expect any promptor easy results . Nee dless to say, wehere at Radio-Electronics edi­toria l will be very interested in the firsthackable. w ide-range , and sane lypriced quarter-horse induction-motorspeed -control construction project.

Electric-motor resourcesTo get you sta rte d, I've put to­

ge the r some elec tric -mo to r re­so urces fo r you in th e reso urcesidebar this month. Here's a quickrundown ...

One very good starting po int is the$5.00 Small Motor and Gearmotorhand bo o k fro m B o din e. W. W.Grainger, of course , is by far the lead­ing wholesale distributor of just aboutany type of small motor. And yourbest source for electric motor hack­ing books remains Lindsay Publica­tions .

Good surplus motor sources in­c lude C & H S ales , N o rthern ,JerryCo, Herbach and Rademan, andFair Radio Sales. Two higher-volumesupp liers of sma ller motors areMolon and Fasco.

As we 've just seen , one interna­tio nal source for AC -induction motor­speed co ntro ls is Asea Brown Bavari.

Important trade journals involvingmot o r s in clud e M otion , PCIM ,M a chin e D e s ign , App l ia nce ,Appliance Manufacturer, and DesignNews.

Some of the more scholarly stuffcomes down in either of the IEEETransactions on Energy Co nversionor their IEEE Transactions on Indus­trial Application s. For automotivemotor uses, try the publications in theSAE library.

Uh, even though this is one of ourlonger resource listings, I've got ahollow fee ling I'm miss ing several ma­jor and obvious mot or hacking re­so urces here . Som eth ing that yo uelect rica l types out there might beable to help us on .

So , for the first of this month's con­tes ts, let me know what I've left offthe sidebar in the way of motor re­so urces . They ' ll be all t he usualInc redible Secret M oney M achin ebook pr izes , along w ith an all ex­pense paid (FO B Thatcher, AZJ, tinajaquest for two go ing to the best entryof all.

Or, as a second contest , just add toour ongoi ng induction motor speedcontro l dialogue in some use ful way.

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Making waveletsThere's a brand-new math revolu­

tion tak ing off that appears certa in topro fo und ly cha nge mu ch of w hatelectronics is and what it wi ll be ableto do . All the noise is over wavelettheory, an incred ibly powerfu l newtechnique that promises to blow the

For our third contes t this month ,just tell me what you wo uld do withone or more cascaded dual digitallycontrolled potent iometers .

yo ur substrate pin. Thu s, yo u caneasily handle bipo lar analog signalsthat go above and below ground.

Your maximum clock frequency is10 MHz , which means you can up­grade your potentio meter setti ngs asoften as 580 kHz or so . Their se riesw iper resis ta nce is typic ally 400ohms, and you're allowed a maximumpotentiometer or wiper current of onemilliampere . Be sure to see the datasheet for additional specs and timingdetai ls.

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FIG. 5-S0ME KEY PAPERS on the new wavelet math theory which is now revolutionizingjust about everything in electronics .

A New wave in applied mathematicsB. Cipra , Science 24 Aug 1990, pp 858-859.

New wave number crunchingC. Brown EE. Times, 5 Nov 1990, pp 31-34

Video compression using 3D wavelet transforms.A. Lewis, Electronic Letters, vol 26 no 6 pp 396-8.

Non-orthogonal wavelet representations in relaxation networks.J . Daugman, New Developments in Neural Computing, pp 233·50.

A theory fo r multiresol ution sig nal decomposit ion.S. Mallat, IEEE Transactions on Machine Intelligence, v11-7 pp 674-93 .

Wavelet transformation in signal detection.F. Tuteur, 8th IFAC/IFORS Symposium, vol 2 pp 1061-5.

Entropy reduction and decorrelation in visual coding.J . Daugman, IEEE Trans. Biomedical Engineering, vol 36 no 1 pp 107-14.

Wavelet transformation in signal detection.F. Tuteur, ICASSP Speech Conference 88, vol 3 pp 1435·8 .

Complete discrete 2-D Gabor transforms.J. Daugman, IEEE Trans Acoustics & Speech, vol 36 no 7 pp 1169-79.

Dispersive noise removal in t-x spa ce.Beresford-Smith, Geophysics USA, vol 53 no 3 pp 346·5 8.

Adaptive dec onvo lut ion by lattice filters.S. Persoglia, Bulletin of Geophysics Theory, vol 27 no 107 pp 169-83 .

A critique of seismic deconvolution methods.A. Jurkev ics, Geophysics, vol 49 no 12 pp 2109-16.

Statistical pu lse compression .E. Robinson, IEEE Proceedings, vol 72 no 10 pp 1276·89 .

200-year-old Fourier analysis, syn­thesis, and transforms completelyout of the water.

Why worry about some obtusenew math theory? Well, first of all,because it's there . Second, becauseit 's a sure f ire winn ing topic for aschool paper. And th ird, there's a lotof electronic doors about to suddenlyget slammed in yourface if you do notouickly pick up on exactly what wave­let theory is and what it can do foryou .

Fouri er ana lysis is , er-bettermake that was, a method of givingyou a second way of looking at anddealing with electronic signals. Be­sides the int uitive or "real-world "time domain, Fourier techniques letyou create a separate frequency do­main. Things not at all obvious in thetime domain become quite clearwhen they are in the frequen cy do­main, and vice versa.

For instance, a square wave in thetim e domain is ju st a si gnal thatkee ps boun cing up and down be­tween tw o levels. In the frequen cydomain, that same square wave canbe shown to co ns ist of an infi nitestring of sine waves. Specifically, youcan build up a square wave from itsfundamental sine wave, one third itsthird harmonic , one fifth the fifth har­monic , and so on up the line.

A few of the zillions of places that

the frequency domain can become. important include spectrum analysis,holograms , video· image compres­sion , music synthesis; side- lookingradar, picture deblurring, etc .

But the big problem with Fourieranalysis is that everything was con- \nected to everyth ing else . Make eventhe slightest change, and you had togo back to square one and recom­pute everything. And while Fourierseries is a great way to handle mostof a square wave, it sure has troub leswith the suddenly changing leadingand trailing edge s.

What wavelet theory does is letyo u se le c ti ve ly mi x and mat chwavelets that can both deal locallywith sudden change s and globallywith average s and backgrounds . Youcan thus selectiv ely apply all yourmath power precisely where it w ill doyou the most good, and do so withspeeds and efficiencies that were to ­ta lly unheard of with t raditiona lFourier analysis .

What wavelet theory does is letyou selectively m ix and matchwavelets that can both deal locallywith sudden cha nges and globallywith averages and backgrounds. Youcan thus selectively apply all yourmath power precisely where it will doyou the most good, and do so withspeeds and efficiencies that were -to­ta lly unheard of with trad it iona l

Four ier analys is.Figure 5 shows a few of the newer

key papers involving wavelet theory.Start out with the Science and E.E.Times overview summary stories be­fore you get into the heavy stuff. Letme know if you want to get into thisany deeper.

New tech literatureThe prices of br ight-red vi sible

laser diodes are start ing t o dropbunches , with a $45.00-in-singlesunit now being offered by Haltek Elec­tronics . They are the newer, high-vis­ib ility 630-nanometer wavelength ,which is same as helium neon . Planon $5.00 visible lasers with in twoyears or so .

New data books for this month in­clude that Special Purpose LinearDevices entry from National. Be sureto check out thei r LMC835 digitally­controlled graph ics equalizer you' llfind on page 1-227.

Three other new data books arethe Logic Databook from theIntegrated Device Technology folks,a new Optoelectronics and ImageSensors from Texas Instruments, andan Integrated Circuits Data Book#33B Supplement from Burr-Brown.

Stat ic memory RAM specs 'cleverly disguised as baseball tradingcards are being offered by SGS in anunusua l promotion . Those are thesame folks that previously gave yousoup cans full of assorted free inte­grated circuits and soap boxes full ofEPROM 's.

Three interesting new surp lus cata­logs showed up in today's mail. Theyi nc lude Circuit Specialists ,International Micro Electronics, andH&R Enterprises publications .

Turning to my own products, for thefundamenta ls of digital integrated cir­cuits, be sure to check into my clas­sic TTLand CMOS Cookbooks. And ,as you can tell from my nearb ySynergetics ad , we' ve now gotHardware Hacker III and Ask the GuruIII reprints available, as we ll as somenew PostScript books.

Also, a reminder that I do have thisgreat new PostScript PSRT roundta­ble and library up on GEnie. You'llalso find lots of Hardware Hackerandall of the M idnight Enginee ring re- ri1prints and other resources here. gJ

Finally, I do have a new and free ~

mailer for you whic h includes dozens ~

of insider hardware hacking secret re- <0

sources . Wri te or call for info . R-E ~

77

COMPUTER CONNECTIONS

Windows pains land pleasures)

JEFF HOLTZMAN

FIG. 1-HERE IS WINDOWS AT WORK, showing a few of the best Windows products.

Phone Book Entries In E:\XTALK\XWP

Font issuesI love my LaserJet II. but some­

times wish I'd never bought it. For the

use it's very hard to notice much dif­ference.

Enhanced doesn't work for me,however. The problem manifests it­self as an occas ional keyboard lock­up, seeming ly w ithout cause. Onlythe keyboard dies; I can still use a .mouse to save files and shut downWind ows. Then it's time for a coldboot. Not e: The probl em happen sonly in Enhanced mode, not in Stan­dard mode or DOS.

It first happened when I installed asca nner- interface card. In t rackin gdown the prob lem. I spoke with Mi ­crosoft and the PC manufacturer tono avail. and ended up locating thecard in another com puter. However.after installing a Lantastic network in­terface card. the problem resurfaced .This time. however. the adapter hadto remain in the computer. Trying toreso lve the problem. I have spe nthours on the phone wi th Microsoft,the PC manufactu rer. and the man­ufactu rers of the inte rface cards. Inthe process I've received severa lBIOS upgrades . hin ts abou t key­board sett ings in Windows' initializa­tion files, and lots of finger pointin g.all to no avail.

The only solut ion is to operate ex­clusively in Standard mode. 1 lose myenvelope printer. the ability to multi­task DOS apps, and the ability to runthem in w indows . In standard mode,when you make a DOS app current,W indows clears the screen, swapssome stuff to disk . and then lets theDOS app do its thing . The swappingprocess is slow and distracting .

On the other hand. standard modeis more than bearable when runningonly Windows applications. For ex­ample. you can start a 2400-bps filetransfer and go do some thing else . Iregularly transfer megabytes of datawhile working undistracted in Wordfor Windows, Corel, ToolBook, etc .

Prlnll:r In OulCaptur e

c uss ed be low) . I use d t o runProComm in a window. uploading anddownloading files. while I worked in aWindows word processor. Tech ­nically. it worked; I was able to sendand receive files at 2400 bps withouterror. However. keyboard responsewas ext remely slow, and screen up­dates were distracting . If you've everused Desqview, yo u know how itfeels.

Another example of why enhancedmode is useful : Several years ago Iwro te a TSR (term inate and stay resi­dent) progra m for printing envelopes .On a word processor. I put the cursoron the address bloc k of a letter. loadup the LaserJet , press a hotkey. andout comes a nicely formatted enve­lo pe. When runn ing in Enhance dmode. I can bring up the word pro­cessor (in the graphical simulated­text mode ) and the TSR still works .

A s for sp e e d. I ' ve s ee nben chmarks th at show Enhancedmode to be about 15% slowe r thanStandard mode (while running Win­dows . not DOS. prog rams), but in

..~ [lie f.dit Yiew In!O ert f orma! Utilities MiCrO-W indow _.!J.~!P.

Font: [~.~~~~m Pt:;: [Om C!lI0 .u.. Jt!

Style: INormlS1 1m'!f Ox 0.; -;:; _

t .' f ile f dll Actions Eetup

-- MicrosoftWord · BENCH912.DOC

Last month. we discussed howand why Windows is going toirrevocably change the PC in­

dustry. Now let's look at how to putWind ows to use today.

You probably know that Windowscan run in three different modes:Real. Standard. and Enhanced. Realmode should have been called Unrealmode. because it is so slow that it'sunrealisti c to expect anyone to use it.Real mode was created for marketingreas ons . not techn ical ones . W in­dows will run on an 8088. and olderapp licat ions w il l run under it. Butyou'd have to be crazy to want to.Even on a relat ively fast (16-M Hz)386. real mode is much slower thanthe other two mode s.

Technically, Enhanced mode is themost sophist icated. It allows you torun regu lar DOS appl icati ons on ­sc reen in graphics mode . in si mu­late d text -mode w indow s. simu lta­neously w ith regular Win dows ap­plications. For example. before I got areal W indow s co mmunica t ion pro­gram (Crossta lk for Windows , dis-

(J)oZoa:I­oW-lW

6o. «a:

78

R-E Computer AdmartRates: Ads are 2Y.t x 2Vs". One insertion $995 each. Six insertions $950 each. Twelveinsertions$925 each. Closing datesame as regular ratecard . Send order with remittance toComputer Admart, Radio-Electronics Magazine, 500-B Bi-County Blvd ., Farmingdale, NY11735. Direct telephone inquiries to Arline Fishman , area code-1-516-293-3000. FAX1-516-293·3115. Only 100%Computer ads are accepted for this Admart.

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BP135-Abeginners guideto the Commodore64 pre-sents massesofusefuldataand programming tips, aswell as describing how toget the best from thepowerful sound and graph- '- --'ics faci lities. We lookat how the memory isorganized , random numbers and ways ofgenerating them , graphics-color-and sim­ple animation , and even a chapter on ma­chine code . Get your copy today. Send$5.00plus$1 .25 for shippingin theU.S.to Electronic Techology Today Inc., P.O.Box 240 , Massapequa Park, NY11762-0240.

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amoun t of unbillable t im e I havewasted on soft fon t prob lems, I co uldhave bought a PostScript printer.Wind ows has a mech anism for insta ll­ing so ft fon ts , but soft-fon t installa­tion programs have a habit of reallymessing up WIN.IN!. Several t imesthe file has gotten so badly screwedup that I had to re- install Win dowsand so me apps from sc ratc h. Anddon 't forget about ded icating 10 or 20megabytes of space just to sto re theco mmon sizes of ha lf dozen fonts.

That said, I've fo und Bit st reamfont s to be the most reliable and ofthe highest visual quality. They are ,however, expensive compared withthe fonts sold by some ven dors , andth ey' re also limited as to specialeffects . The best package I've foundfor generat ing w ild headline fon ts andthe like is M oreFonts , from Micro­Logic Corp.

Flash : a copy of Ado be 's ATM(Ado be Typ e M anager) just arrived. Itis the eq u iva le n t o f p u t t i ng aPostScri pt font engine insid e W in­dows itself, and be cause fon ts arescaled as they are ne eded, disk stor­age is minimal-abo ut a megabytefo r 35 fonts, eac h of w hich can besca led as needed to any reasonablesize . Of co urse wh at yo u gain in stor­age space, you lose in processingspeed ; f ile print ing and screen up­dates take lon ger becau se fo ntsmust be built as they are needed .

To alleviate that problem, ATM re­serves a user-selected amou nt ofmem ory for a font cache; figure atleast lOOK; 500K works, and for doc­ument s with lot s of font changes, amegabyte is better. The basic ATMincl udes Times , He lveti ca, C ourie r,and Symbol fonts; at abou t $ 100 list,it's a stea l. Note: ATM does its tri cksw ith PostScript print ers, LaserJ ets,and most common do t -matrix de ­vices (Proprinter, Epson, etc .r, buton ly wi th text ; it can 't print PostScri ptgra phics . The Plus Pack adds 22 ad­ditional fonts , rounding out the typi calPostScri pt co mp lement.

Windows applicationsI'd like to be able to operate ex­

clu sively in Windows, but cannot doso yet. There are extre me ly powerfulprograms in some areas , and a com­plete dearth in others . W hat I missmost is a decent f ile manager-Win­dow s' ow n fi le manager is awkwardand limited. It doesn't even show theamount of free and used space on adisk drive . What's needed is a W in­dow s version of Magellan, probablythe best DOS fi le manager on themarket.

Even so, the bas ic Windows pack­age is surprisingly powerfu l. Severalo f the major applicat ions-Write ,Paint , Terminal-are as powerful asdecent stand-alone packages of justa few yea rs back . In a way, the Win -

dows apps really are more powerfulthan the old stand-bys , because theywo rk together, smoothly and eff i­c ient ly. You can use Term inal to trans­fe r fil es in th e backgro und w hi leworking elsew here. You can crea teattract ive draw ings using Paint andpaste them direct ly into w rite . BothPaint and Write w ill us e wh ateverfonts yo u have install ed on you r sys­tem . I can see W indows 3.0 beingused by anyone w ho doesn't needthe utmost in power.

The follow ing are my pick s for bestW indows product s.Word processing: Word for Win ­dows. A llows multi-fi le ed iting , multi ­ple views into the same file via (w hatelse) panes ; a macro language aspowerful as some versions of BASIC;efficient style sheets; the ability toload and save fi les directly in Word­S tar, W ordPerf ect , and other fo r­mats; out lining ; grap hics import andprintin g. Cou ld substi tute fo r desktoppubli shin g in many circ ums tances ,but it is indisputably large and slow.Telecomm: C ro sstalk for Win ­dows. Ext remely powerfu l script lan­guage for automat ed t e leco m msessions . Run s beaut ifully in thebackground ; minim ize it to an ico n,and it displays pe rcent of tra ns fercomplete, beeps w hen done.Ut ilities: hD C's Fir s tApp s. Pro ­vi des rea l-time me mory-usage di s­p lay, ab i l i t y t o s ave c o m p le t e

"mco:DC}>­:D-<<D<D

79

• CrossTalk for Windows ($195),DCA, 1000 Alderman Drive, Alpha­retta, GA 30202-4199.(404) 442-4000.CIRCLE 47 ON FREE INFORMATION CARD

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• Gorel Draw ($XXX) , Gorel Sys­tems Corporation, 1600 Carling Ave­nue, Ottowa, Ontario, Canada K1Z8Rl.(613) 728-8200.CIRCLE 34 ON FREE INFORMATION CARD

ITEMS DISCUSSED

• Adobe Type Manager ($99), Plus • FirstApps ($99.95), hOC Cornput-Pack ($198), Adobe Systems lncor- er Corporation, 6742 185th Avenueporated, 1585Charleston Road, P.O. NE, Redmond, WA 98052.Box 7900, Mountain View, CA (206) 885-5550.94039-7900. CIRCLE 46 ON FREE INFORMATION CARD

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• Windows 3 Companion, Lori l .Lo renz and R. Michael O'M ara($27.95) , Too/Book Companion,Joseph R. Pierce, ($27.95) , TheCobb Group/Microsoft Press, OneMicrosoft Way, Redmond , WA98052-6399.

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ASK RE

tro ller is hard eno ugh even when youhave all t he documentation for thecomputer. To try doi ng the same thingwith a complete ly unknown machinethat has no support ing paperworkand (so you say) no I/ O ports stri kesme as an exercise in futility.

How yo u expect to contro l lightsusing a machine w ith no I/ O ports isbeyond me. And adding them to amachine for which you have no paper­wo rk , and built by a company youcan't get in touch with is a job onlySisyphu s would want.

If you've got the urge to build ahom e co ntro lle r, yo u ' ll be much,much better off spending five hun­dred bucks or so for a PC clone andusing that as the basis for the project.You' ll have a known machine w ith realports and languages available to w ritethe softwa re.

I don't like to discourage anybodyfrom doing whateve r project they setth e ir minds to , but yo urs is onlyslightly less diffi cult than striking amatch on a bar of soap. R-E

co ntinued from page 16

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Wind ow s enviro nme nt and rel oadlater. Good alarm clock too. Updateswill provide file manager and Lap-Linktype co mmunicatio ns.Desktop Publisher: Ventura Pub­lisher 3.0 is pretty much a stra ightport from the GEM version; it pro­vides exce llent table and equat ionedit ing, automatic counters, table ofcontents, indexing. PageMaker 3.01mere ly adapts 3.0 for Win 3; PM 4 isdue out around the t ime you read this,and is eagerly awaited .Illustration: Co rel Draw has a mini­malist user interface that continuesto amaze me with its power. I w ish itdid a better job with small font sizes,displayed a visib le grid, did arrays,and allowed symbols.Screen Capture: My unabashedfavorite screen -capture and print pro­gram is Pizazz Plus. The current ver­sion only partially supports Windows;full W indows support should be out ­by the time you read th is.'Development Environment:Tool Book . For use r-interface pro­totyp ing, there's noth ing like it. Ex­t remely powerful and fun.Games: I'm not much of a gamester,

but I've seen a few Windows gamesthat are att ractive. Microsoft has re­leased an Entert ainment Pack w ith avers ion of Tetr is, several card games ,a screen blanker, and more. A lso , I'veco llec ted a few shareware gam es(Ch ess , Checkers , a Tetri s c lo ne)that I'll post on the R-E BBS.Books: M icrosoft's W indowsUser's Guide is infinitely better t hanprevious versio ns, but is really a refer­ence guide. The Windows 3 Co mpan­ion provides a view from the user 'sperspec tive. For ToolBook program­ming, the Too/Book Co mpanion in thesame series is quite useful.

ConclusionIf I complained about Windows, it's

only because it's wo rth complainingabout-I see plenty of bad softwa rethat isn 't wo rth the magnetic ink it'sprinted on. In spite of my comp laints, Ireally like Windows. The program isnot perfect, but it got a who le lotbetter with vers ion 3 .0. This versio nis more than just a passing fad be­cause it represe nts not just a newway of doing th ings, but a bette r way.Try it-you really wi ll like it. R-E

80CIRCLE 67 ON FREE INFORMATION CARD

Last month we traced the inter­twi ned history of some of theimport ant New England-based

loudspeaker manufacturers. Withoutexag ge rat io n, it ca n be sa id th atth ose companies es tabl ished newtechnical standards for home loud­speakers. In general. their productswere smoother, had w ider range, andhad far less co lo rat ion than ei therprevious designs or those of most ofthei r co mpetitors on the West Coas t.Al thou gh I covered on ly the mostprominent New England compan iesand desig ners , I'm sure that there areothers wh o made con tr ibutions thatalso advanced the state of the speak­er art .

As discussed in last month 's col­umn, one of today's leading manufac­turer s of high-qu ality speaker sys ­tems is Boston Acou stics. Last fall Ihad the pleasure of vis iting BA 's new,highly auto mated plant and spendingthe day with the president of the com­pany, And y Petite. In the cou rse ofour convers ations , we touched on anumber of issues and matters thatare of co ncern to anyone interestedin how loudspeakers are designedand manufactured-and particularlywhat makes them sound good. Whatfoll ow s is a rando m se lect io n ofAndy 's views, somewhat condensedand paraphrased.• As you know, the crossover net ­works found in today 's speake rsrange from the incredibly complex tothe surprisingly simple. We try to de­sign the simplest possible crossoverthat will do the job in a part icular sys ­tem. Man y of the co mponents thatyou see in co mplex crossovers are inthere to co mpensa te for the deficien­cies of the system 's drivers. For ex­ample, if you design a woofer wi th asmooth respon se at the crossover­frequency area and above-which isthe right thing to do with respect tooverall performance-you can con­siderably sim plify your crossove r net ­work . Not only does that save money,but it also minimizes power losses

AUDIO UPDATE

The Boston Sound: Part II

and provides a smoother impedancecurve for the amplifier to drive.• In pr od uc t io n, o ur asse mb ledcrossovers are checked against a ref­ere nce net work to a to lera nce of± 0 .5 dB. Aside from helping ensurethe frequen cy performance of thesys tem as a whole, that procedureeliminates the crossover assembly asthe cause if system response is notup to spec in the final checkout.That's impo rtant because, while it'seasy to replace drivers if necessary,it's a real pain to get to and fix acrossover once it's finally installed inan enclosure.• We usually prefer to use aco ustic­suspe ns io n woofers rath er thanbass-ref lex or vent ed des igns for tworeasons: The woofer in a vented sys­tem is inherently uncontrolled belowits low-frequency cuto ff. The very lowfrequencies generated by turntablerumb le and tone-arm resonances cancause excessive cone excurs ions inthe infrasonic area and, therefore, in­termodulat ion dist ort ion at aud iblefrequencies . Of course, as LP's fadefrom the marketplace, the sonic prob­lems produced by the equipment thatis used to play them will also disap­pear.

Another difficulty has to do with the

FIG . 1-BOSTON ACOUSTICS ' SW10powered subwoofer features a 100-watt in­ternal amplifier with electronic crossover.

LARRY KLEIN

way a woofer ages . Its suspensionbecomes more compl iant over time,which can mistune a crit ically tunedvented sys tem. In contrast, an acous ­tic suspension design is relatively im­mune t o bass-response changesthrou gh woofer aging. Both of thoseproblems are a lot less severe thesedays, although we question how wellsmall and/or inexpensive vented sys­tems react to the strong low bassfound on many CD's.• When it's tech nically and eco nom­ically feasible -to do so , there's a defi ­nite advantage in direc tly powering awoofe r o r su bwoofe r. By elec­troni call y con t ro lling the cha rac­teri sti cs of the s igna l fed to thewoofer you can easily achieve verylow frequency crossovers, responsecurves, and very steep rolloff s thatwo uld be quite impractical with pas­sive inducti ve/ capacit ive networks.That allowed us to use a vented sys ­tem fo r our powered subwoofer­which has the advantage of reducedexcursion at low frequencie s com­pared to an aco ust ic suspension­with out ,running int o th e infrasonicproblems I just mentioned.

You can also avoid many type s ofacous tic problems wi th non-poweredvented designs by des igning them fora goo d low-bass response. If the cut­off frequency is made low enough,the speaker will be contro lled prop­erly down to the lowest musical fre­quencies.• There 's a com mo n ass ump t io nthat the larger the woofer in a system,the better the bass. But for a largewoofer to be effec tive it must be in­sta lled in a large enough enclosure.For examp le , if you put a 12-inchwoofer in a 1.5-cubic-foot enc losure ,the small volume of the enclosed airraises the system resona nce, and thebass response decreases. To restore riithe bass you have to add more mass ~to the cone, and then use a heavier j;magnet to maintain effic iency. That is ~

not a ve ry cost -effecti ve process . (0

The only advantage of a large cone (0

81

been giving papers on phase-correctcrossover networks. At one point heand a grad student dec ided to build aspeaker system based on the pro­fessor's theories . It turned out thatthe system didn't work very wel l be­cause real-world drivers have a com ­plex imp ed an ce , quite unli ke th eresistors on which the des ign calcula­tions had been based. The next yearhis paper was based on his work withreal world drivers .• Except w hen dealing with au­dioph iles, speaker designers have al­ways had a tough job satisfyinginterior decorators , architects, andothers who wou ld prefer that speak­ers be heard but not seen. Elect ronicwoofer co ntro l has made possiblesubsta nt ial reductions in cabinet sizewhile sti ll realizi ng adequate bass .However, the laws of physics put alim it on how loudly a very smallwoofer can play and how low it can goeven with everything optimized. Built­in wall speakers and subwoofer/sat­ellite systems are two variable solu­tions to make speakers invis ible, orat least unobtrusive in the home orworkplace.

A final word : Andy Peti te's viewson speaker des ign should be par­t icularly interesting to anyone wholikes to know the techn ical thinkingand design process behind commer­cial audio products . As the proof ofthe pudding is in the eating, so toothe test of any des ign approach is theperformance of the product. To myears, Andy's thinking-and des ignapproach-make an exce ptiona lamount of sense. R-E

woofer is a somewhat higher max­imum output level-assuming that it'sinstalled properly in an adequatelysized box. If you can get the loudnesslevels you want with sma ller cones ,you are better off using them-inpairs if necessary. Using small conesin pairs has definite advantages.• Some of the bas ic enclosureground rules change when you 'redealing with car-stereo speakers orspeakers meant to be flush mountedin a wall. In both cases , we design thewoofers wi th a fa ir ly st iff-suspen­sion-which makes them more rug­ged-because their free-air reso ­nance is not shifted upward to anydegree by the mounting. In genera l,there is not a significant variat ion inthe rear loading seen by woofers inmost car installations. We get a verygood correlation between tests in acar door or rear package shelf andtests done with the woofer mountedon a simulated infin ite plane baffle­in other words, a large sheet ofplywood.• Over the years I've observed thatthere is a real dichotomy between theviews of the emp irical and the the­oretical speaker des igners . For ex­ample, for years the academictheorists wou ld give loudspeaker-de­sign papers at various Audio Engi­neering Society conventions . Thosewere frequently greeted by snickersfrom the des igners in the room, be­cause it was clear that the theoreti­cians had not tried out the ir ideas bydesigning and buildi ng systems. A fa­vorite example: One particular pro­fessor of acoustics had for years

FIG. 2- BOSTON ACOUSTICS ' 380 is the sm allest 8-inch, two- way, f lush-mount speakersystem availab le.

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ARTWORK created for use in printed circuit boardproduction from your engineering schematics. Pro­fessional quality hardcopy, Gerberfile, or Photoplot­ter outputs. Reasonable rates. Send for details to:JTD ENGINEERING , 10628 Grandview Place, AltaLoma, CA 91701.

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CB Tricks II book. Power amplifier design and theo­ry, UHF CB tune ups. Send $19.95 MEDICINE MANCB, PO Box 37, Clarksville, AR 72830 .

CATALOG: hobby/broadcast ing /HAM /CB: CableTV, transmitters, amplifiers, surveillance devices,comp uters, more! PANAXIS, Box 130-F2 Para-dise, CA 95967 . '

AMAZING device disables any remote keychain caralarm via radio! Cheap one evening project. Sell tocar "Repo" companies for hundreds $profil! Or justfool friends and neighbors. Complete theory andplans $12.95. HUMAN MOVEMENT SYSTEMS,131-30 234 St., Rosedale, NY 11422.

DESCRAMBLlNG, new secret manual. Build yourown descramblers for cable and subscription TV.Instruct ions, schematics for SS AVI, gated sync ,sinewave, (HBO, Cinemax, Showt ime, UHF, adult)$12.95, $2 .00 pos tage . CABLETRONICS, Box30502R, Bethesda, MD 20824.

TRANSMIT VCR to any set in house. Inexpensive.No constructio n. Complete instru ctions. $4.00 .VENTURA, Box 377, Beverly, MA 01915.

AUDIO ! Plans/products - inexpensive, profession­al, amps, mixers, more! Literature/casse tte - $3.00!DAVISOUND , Box 521, Newberry, SC 29108.

INVESTIGATORS, experimenters - Quality newplans. Micro and restricted devices. Free catalog.Self addressed stamped envelope required KEL­LEY SECURITY INC., Suit e 90, 2531 SawtelleBlvd., Los Angeles, CA 90064 .

MIDI and music accesso ries, plans, kits, and as­sembled, catalog $1.00, M-SEQ, Box 231233, SanDiego, CA 92194.

Jerrold, Zenith, Hamlin, Sci. Atlanta. Pioneer& MORE! OUR PRICES ARE BELOW WHOLESALE!

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BUILD from easy-to-follow schematics: audio mix­ers/e qua lizers (stage, stud io , bu sin ess , hom e,basic to sophisticated), feedback controllers, activefilt ers. guitar supe r-fuzz box, loud speaker en­closures (including carlvan), power supplies, more.vSSE reliability. Send $5.00 for descriptions. Rea­sonable prices. VON SPRECKEN SOUND ENGI­NEERING, Dept. B, Box 1315, Clinton, MS 39060.

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pcrrv interface - RGB to TVlV ideoN CR. Switcha­ble between PC and composite video inputs. Chan­nels 3 or 4, RF output. Complete PC card kits$59 .95 . PC boa rd only $19.95 . INNOVONICSCORP., 9 Bartlet St., Dept. 36, Andover, MA 01810.

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MOOEL H'xw· x O' MATCHING PRICELG·1273 3' 12' 7' TA·2800. TA·377A. TA·2200 .. S22 85LG·1684 4' 16' 8' TA·323A. TA·377A. TA·2200 27.50LG·1924 4' 19' 11'h TA·802. TA·820A. TA·1500.TA120MK2. TA·800. TA·l000A 32.80lG·1925 5' 19' 11'h TA·477. TA·800. TA·1500. TA·l0 00A. TA·3600 3580lG·1983 2",19' 8' TA·377A..TA·2800. TA·2200. TA·120MK2 29 25

SM-666 m-eta fc abinet• Free gift for any purchas e before April

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S69.502176217623.65

KIT ASSEMB.

..... s

.. . .. 15.65..15.65

....... .... ......... 16.75

OESCRIPTIONDIlJital Voice Memo ........•.. . .. ..... ........................• S30.00Multi-PurposeMelody Generator . ,.. 1284Multi-PurposeMelody senerarcr a . . . 13.6535WClass"A' Main Power Mono Amp , ...... . 31.5030W Multi-PurposeSingleChannelAmp. .. . 20.0060W+ 60WStereo Power Amplifier (With Mic. mput) .30W X2 StereoPre-main Amp. .... . 31.50Hi-Quality FET StereoPre-Amp. . . 59.9540W Solid StateMono Amp . . 28.00120WMostet Power Mono Amp. . 6800120W+ 120W low TimPre-Main StereoPower Amp ,.' ,63,9280W+ 80W DCStereo Main PowerAmp ,.45,94 59,7260W+ 60WDCl DC Pre-MainStereoAmp, , 40.39 4937100W DynamicClass 'A"MamPowerMono Amp 59.69 80.58100WX2 Class "A"DCStereo Pre-Main Amp , 73.70 95.81FetSuperClass'A"DCPre-Amp. 47.70 5824Electrcmc Echo & Reverberation Amp. * 96.00HQPre-Ampwll0 band graphic equalizer * ._........ 6880HI-FETICPre-Ampw{J waytonecontrol 48.90 63.57Stereo Simulator(For MonoTVor Any MonoSource) ...... . 27.00 3850300W HQ HI-F. Power MonoAmp . 85.00 110.00

0-15V2A Regulated DC Power Supply (W/Casej* ...0-15V5A Regulated DC Power Supply .0-30V3A RegulatedDC Power Supply .0-50V3ARegulated DCPower Supply .

POWER SUPPLIES

MOOELTA·28MK2TA·50A /BTA·5OCTA·120MK2TA·300SM·302TA·323ATA·377ATA·400TA·477TA·BOOMK2TA·B02TA·B20ATA·l 000ATA·1500TA·2200TA·2400ATA·2500TA·2800TA·3000TA·3600

TR·l00ATR·355ATR·355BTR·503

.,'" k , -c- ".1,';' c-eo: c.ra.-. t.lo· L·1 O'OC'S c,,,_·;: ~ .1"0 COD Q'dt!ls CO D le e ,5 55 00 M,nLmUm o-oe- ,5 $20 00 • We snIp DrUPS OIOuno .oao e USIm,n S3 00 1ana Sf',p by USmaLi Business & Show room hours : (Pacific Time)c ..t-, o- vs P ' ·, l ~t· C.I.. CI ..' "'.1es dt'P. l' !"'t"'! '0' c-oco 0 ~1'" 2 os OIIOft:'911 Of(Jt~IS • Allas!>Cm~ro unllS ha ve a J Ooay s w,lflanly • OYal'ly or v orcroe c.scocet a va ,lable upon f€'QuI'SI • Res~nls Mon. thru Fn. 9:30 am to 5:00 pmo' CA ;It·.I ,· .100 :"1 ""' 1,1' 6 :5 , • A · "C ' l " .l '·d , ~ t· ,Ire s"O,ec t to Pf,O' S,lil' P rc c s a te sul>jt.'C110 eh,lnge w.tnc ut O',Of oorce We a rc nOl euspcn sb'e 10f lyPOgrall'cal eftOfS Sat. 10:00 am to 5:00 pm

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INSTRUMENTS KIT ASSEMB.

"III '

3lo'1 Multi-Functional led D.P.M. (w/ABSplastic easel _ S34.504~ Hi-PrecisionoP.M "''' . _ 38.004\1: HI-PrecisionD.P.M. (w/ABSplastic case)............••... .........•.. 41.2031h Multi-Functional LCD O.M.P. {w/HoJd FunctIOn)...... .... ...... 36.00150MCDigital FrequencyCounter........ ...79.001 GHz FrequencyCounter * ....

"· ; 11

"I

'III'II

MODEL001002003004005006007

OESCR IPTIO N28Vx 2 6Ato 30Vx2 6A36Vx2 3A40Vx2 6A24Vx2 6A26Vx2 3A18Vx2 5A53Vx 28A

MATCH ING PRICETA·800. TA·802. TA·820A. TA· l000A. TA·1 500 S2700TR·503. TA·323A. TA·400. TA·300 2200TA·477 ." 2800TA·120MK2 ....2200TR·355B .... 16.00TR·355A . 1550TA·3600 . .. .. . .....43.00

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CIRCLE 93 ON FREE INFORMATION CARD 91

BeaTV/VCRRepair Specialist

NOW youcantrain at homein spare time lor a money-makingcareer as a TVNCR Repair Specialist. No previous expen­

ence necessary. No need to quit your lob or school. Everythingis explained in easy-to-understand language vllthplenty 01 draw­ings. diagramsand photos. We show you howto troubleshootandrepair video-cassette recorders andTVsets. howto handlehouse callsandshop repairsfor almost anymake01television orVCR. Tools are included with your course so you can get" hands-on" practice as you follow your lessons step by step.Send lor free facts aboutthe exciting opportunities In TVNCRRepair and find out how you can start making money in thisgreatcareer. MAIL COUPON TODAY '03C

r CS SCHiiiiLOF WNCR REPAiR;-DeP'i.ADEiiliSI ",c"'oo 925 Oak Street, Scranton, PA 18515 II

Please send mefulhntorrnation andcolor brochureonhowI canIlearn TVNCR Repair at home in my spare time. I understand

I fhereis noobligation andnosalesman will visit me. IName Age__1

I Address Apt.#__I City/State zip 1L!.h~ L _ l ::J

MAGIC! Four illustrated lessons plu s insid e infor­mation shows you how. We pro vid e almost 50 tri ck sincluding equipme nt fo r four professional effec ts .You ge t a binder to keep th e mat eri al s in, and a one­year membersh ip in th e Intern ation al Perfor mingMagi cian s w ith a plast ic membershi p card that hasyou r nam e go ld-embossed. You get a one -year sub­sc ription to o ur qu arterl y newslett er " IT's MAG IC !"Ord er now ! $29.95 for each cou rse +$3.50 pos tageand handlin g . {New York res iden ts add applicablestate and local sales tax}. THE MAGIC COURSE,50 0- B BiC ou nty Boulevard, Fa rmi ng dal e , NY11735.

EC.C . Commercial General Radiotelephone li­cense. Electron ics home study. Fast, inex pensive !" Free" details . COMMAND, D-176, Box 2824, SanFrancisco, C A 94126.

LEARN IBM PC assembly language. 80 pro­gra ms . Di sk $5 .00. Boo k $18 .00. ZIPFAST, Box12238 , Lexin gt on, KY 40581-2238.

CONSUMER advocate. Help so urces, any prob lem .SASE for descr ip t io n. HELP!, Bo x 132, Ind ianRocks, FL 34635.

ENTER THE WORLD OF PROFESSIONAL VID­EO! Pro 's tell techniques and secrets of U-maticVCR 's 32 pg . Ill us . Send $12 .9 5 to ANIBALNEGRON, 64 Mason Blvd., S.I. , NY 10309.

Copiesofarticles from thispublication are nowavailable fromthe UMIArticle Clearinghouse.'res: I would like to knowmore about UMIArticleClearinghouse. I am interested in electronicordering through the following systemtsl:

o DIALOG/Dialorder 0 ITT Dialcom::JOnTyme ::JOCLe ILL Subsystemo Other (pleasespecify) _CJ I am interested in sending my order bymail.Q Pleasesend me your current catalog and user instruc­

tionsfor thesystemls ) I checked above.

Name _

Title' _

Institution/Compen,' ~---_

Department, _

Address, _

Citv State Zip, _

Phone1__ )' _

,,'IiM'ITlUl 11JJ.\ rtid pcrean nghOlISe

!'-1ail to: UniversitvMicrofilms International300North Zeeb Road. Box 91 Ann Arbor, ~II 48106

Try the

Eliii!:;mll,r;s®bulletin board

system

(RE-BBS)516-293-2283

The more you use it the moreuseful it becomes.

We support 300 and 1200 baudoperation.

. Parameters: 8N1 (8 data bits, noparity, 1 stop bit) or 7E1 (7 databits, even parity, 1 stop bit).

Add yourself to ouruser files toincrease your access.

Communicate with other R-Ereaders.

Leave your comments on R-E withthe SYSOP.

RE-BBS516-293-2283

UNICORN - YOUR I.C. SOURCE!EPROMS

MK4027 .59 .56 .50 4464-100 4.79 4.55 4.104116-120 1.39 1.32 1.19 4464-120 4.19 3.98 3.584116-150 .99 .94 .85 4464-150 3.99 3.79 3.414116-200 .89 .85 .77 41256-60 4.79 4.55 4.104116-250 .59 .56 .50 41256-80 3.49 3.32 2.994164-100 2.59 2.46 2.21 412S6-1OO 2.99 2.84 2.584164-120 2.29 2.18 1.96 41256-120 2.69 2.58 2.304164-150 1.99 1.89 1.70 41256-150 2.99 2.18 1.964164-200 1.59 1.51 1.36 511000-70 12.99 12.34 11.114416-120 5.99 5.69 5.12 511000-80 11.99 11.39 10.254416-150 4.99 4.74 4.27 511000-100 10.99 10.44 9.40

STOCK # 1·24 25·99 100+ STOCK # 1·24 25-99 100+

1702 3.99 3.79 3.41 2764A 3.29 3.13 2.822708 6.49 6.17 5.55 TMS2564 6.79 6.45 5.812716 3.29 3.13 2.82 27C64 4.19 3.98 3.562716-1 3.79 3.60 3.24 27128-20 5.79 5.50 4.95TMS2716 6.29 5.98 5.38 27128 5.09 4.84 4.3527C16 3.99 3.79 3.41 27128A 5.79 5.50 4.952732 3.79 3.60 3.24 27C128 5.79 5.50 4.952732A-2 3.79 3.60 3.24 272S6-20 5.29 5.03 4.532732A 3.69 3.51 3.16 272S6 4.79 4.55 4.092732A-4 3.19 3.03 2.73 27C2S6 5.29 5.03 4.53TMS2532 5.79 5.50 4.95 27512-20 7.49 7.12 6.41TMS2532P 1.99 1.89 1.70 27512 6.99 6.64 5.9827C32 4.19 3.98 3.58 27C512 6.99 6.64 5.982764-20 3.99 3.79 3.41 27Cl 024 17.99 17.09 15.382764 3.79 3.60 3.24 68764 13.99 13.29 11.962764A-20 3.99 3.79 3.41 68766 14.99 14.24 12.82

DYNAMIC RAMS

STOCK # 1-24 25-99 100+ STOCK # 1-24 25-99 100+

PRICE

$6.99$6.99

PRICE

$49.99

10010 Canoga Ave., Unit B-8 • Chatsworth, CA 91311OUTSID E CALIFORN IA : {800} 824-3432 {Orders Only}IN CALIFORNIA: {818} 341-8833ORDER BY FAX: {818} 998-7975

Minimum Order $15,00

DESC. PRICE

25 $1.99100 $4.99

• Includes:Cleaning swabs. head­clean ing fluid , ant i-staticcleaner, screen wipesand cleaning diskette.

STOCK # DESC.

581099 3'12' kit581100 5'1. ' kit

STOCK #

581104581107

STOCK #

L59200

• Individually wrapped• Dispenser pack

• Output: 3 mW• Current: 85-100 mA• Operating Voltage: 2.3-3.0V• Wavelength: 670nm

••• •: ..

Calton

DISC DRIVE& COMPUTERCLEANING KIT

ANTI-STATICSCREEN WIPES

LASER DIODE(VISIBLE-RED)

PRICE

$19.99

PRICE

$39.99

• Output: 4 mW (max.)• Cu rrent: 20 rnA• Operating Voltage: 2.2-3.0V• Wavelength: 665nm

STOCK # PRICE

L53200 $119.99

STOCK #

L5022

• Output: 5 mW (max.)• Current: 65-100 mA• Operating Voltage: 1.75-2.2V• Wavelength: 780nm

STOCK #

581052

• Output: 10 mW (max.)• Current: 90-150 mA• Operating Voltage: 2.2-2.5V• Wavelength: 820nm

STOCK # PRICE

581053 $9.99

• Output: 2.5 mW (max.)• Current: 90-150 mA• Operating Voltage: 2.2-2.5V . ~Ii!'!.:O~'~

• Wavelength: 820nm• Collimation: .18mrad (typ.)• Size: 11mm diameter

Al\=~=

1- JI VISA'

LASER DIODE(VISIBLE-RED)

LASER DIODE(INFRA-RED)

~=

COLLIMATOR PEN(INFRA-RED)

LASER DIODE(VISIBLE-RED)

c~

(f)oZo((I­oW-lW

oo«((

CIRCLE 194 ON FREE INFORMATION CARD

92

BrandNEW ~automotive-type ~.>-$solenoid (relay). 0 , 1(912Vdc, 4 ohm coil. <::>SPST normally open .Negative chassis ground .

Designed for switching veryheavy loads. 5116"copper screws

on switch terminals.CAli SOL-32 $4.50 each

Phonemate# 104210Base station for a cordless telephone,this transceiver contains hundreds ofuseful parts. Indudes power transformer ,600 ohm phone coupling transformer,crystals , heat sinks, voltage regulator ,power cord, phone cord and jack, \relay and 30" telescoping antenna. . \The beige chassis box has only a few holes in the back panel and would be anexcellent housing for other projects . 7.25" X 5.87" X 2.15".CAli PMB-1 $3.75 each SOLD AS-IS For PIITtS Only. No rMurns accepted.

Rubicon CE210 Mfd 330 Voltphotoflash capadtor.0.79" dia. X 1.1" high.These are new capacitors thathave been prepped with 1.4" blackand red wire leads soldered to theterminals. CAli PPC-210 $1.25 each

10for$11 .00 • 100 for $100.00Large quantities available.

Call for pridng .

MAIL ORDERS TO: ALL ELECTRONICS CORP· P.O. BOX 567· VAN NUYS, CA 91408toto

"TlrnOJJJC~JJ-<

L.E.D. FLASHER KIT

This si""'e device cam be set to dickfrom 20 to 1,000 beats per rri nute.Easy to build, ind udes circuit board, allcomponents and instruct ions. Oper­ates on a 9 volt battery (not Included).CATII METRO $3.75 each

Learn about

stepp ing~.~ - .motors wh ile ~~\ ,. 'building thissimple drcuit.Includes circuh board, stepping motorand all parts except 12 Vdc powersupply. CATII SMKll $lS.oo each

METRONOME KIT

~

Build this variable , " • , .. .. • ..speed led chaser . ;, ~iR1U.R~10ledsflash ~'(\ .,,;.. .sequentially atwhalever speedyou set them for .Easy to build kI1 includes pc board,paris and Instructions . Ideal for speciallighting enects. costumes. etc. Oper­ates on 3 to 9 vahs. PC board is 5" X2.25" . A great one hour projecl.CA Til AEC $6.50 each

STEPPING MOTORCONTROLLER KIT

Two L.E.D: s flash In 1

unisonwhena9vo~ ' ~,;...~battery Is attached .This kI1 includes a ~

p.c. board , alilhe partsand instruc1ions to makea simple flash­er circuit . A quick and easy projecl foranyone with basic soldering skills .CAlli LEOIOl $1.75 per kl

L.E.D, CHASER KIT

OPTOSENSORS

Honeywe ll ;'i'lc'III HOA 0866 -N55 ~"!. 'jU-shaped ooto I' \lsensor . l /S" gap .4 pc leads .

CATIl OSU~ 75c each

TRWII OPB-S1S~U-shapedopto sw~ch . r'O.Z' gapbetween sensor and emitter.

CATIl OSU -9 75c each

TRWII OPB S22SD

Relleclive ~scanner rrodule.U-shaped devicewith 4 leads each e'l.,side (S total) 0.09" gap .0.75" mount ing centers.

CATII OSU-10 75c each

TRWII OPB·7OS (4. C(:,Wedge -shaped I [ 1\reflective opto ~sensor,CATIl OSR-5 75c each

Standard JUMBODIffused T 1-314size (5 mm)

-==RED CAlIILED-1

10 tor $1 .50 "lOOfo1$13.00

GREEN CATII LED-210 fo<$2.00" 100 for $17.00

YELLOW CATII LED-310 for $2 .00 " 100 for $17.00

FLASHING LEDWI bu ih in flash ing clrcuh5 voh operation. T 1-314

(5mm) I=-::'

RED $1.00 eachCA TIl LED-4 10 for $9.50

GREEN $1.00 eachCATIl LED-4G 10 for $9.50

YELLOW $1.00 eachCATII LED-4Y 10 for $9.50

LED HOLDER

Two piece hold ... . :~ eCA TIl HLED 10 for 65c

INFORMATION (818) 904·0524•

ONE MINUTE TIMER

RG-11/U VIDEO CABLE

INSTRUMENT ENCLOSURES L.E.D."5

This white box witha blue button willdrive you crazy.Box measu res 3 1/4"square X Z' high.When the button is peessed 4 LEOs lightand a beeper pulses . Every 15 secondsone led goes out and the speed of thebeeping increases. At the end of 60 sec­onds the unlt gives 011 a long beep followedby a low squelch, all LEOs shut off and theunit stops . Unh requires a 9 voh transisto<battery (not induded) to operate .CAT II TMR-1 $2.25 each " 10 for $20.00

Minimum Order $10.00' All Orders Can Be Charged To Visa, MastercardOr Discovercard • California, Add Sales Tax· Shipping And Handling $3.50For the 48 Continental United States - All Others Including Alaska, Hawaii,P.R. And Canada Must Pay Full Shipping' Quantities Limited· No C.O.D.•

Prices Subject to change without notice.

100ft. or 200 ft. rolisof RG ll/U 75 ohm cableterminated to heavy dutyF connectors. Includes75 ohm terrrinator and 4.a:I=F-61 splie..- on one end . New cables manu­factured for IBM PC networks. IBM PiN150190S COM/SCOPE.CATII RG-11-1 100 ft. roll $15.00CATII RG-11-2 200 ft. ro1l$27.5O

High qualhy moldedQ'~ABS Instrumentenclosures. Integrated ~PC board standoffsand two sets ofvertiQa)mount ing slots for front and rearsub panels. All enclosur es are 6" wide X6 1/4" deep. Choice of thr.... hIS. Includesnon-s kid rubber feet and hardware .Availab le in beige, ivory , black, andblue.P-anlllht. CAn2 1/." CAnMB-A $7.50.aen 101orS65.oo251S" CAn MB-B $7.75.aen 10 lor $57.503' CAT. M~ $5.00 aaen 10 lor $70.00

Please spec~y color.

HEA VY DUTY "C"

RECHARGEABLEBATTERIES

Experimentors Delight ATARI5200 Vidio Game

YUASA1800CNickel -cad heavyduty "C" cell1.2 von, 1800 mahPrice reduced on 10 or more.

CAlli HDNCB-C10 for $42 .501100 for $375 .00

FAX (818) 781·2653Call Or Write For OurFree 60 Page Catalog

Outside the U.S.A. send $2.00postage for a catalog,

SWITCHES

Alar i video game controll ...s relurned to thedealer because of various delects .None of them wo<k properly. but theyhave lots of great parts . A RF videorrodulalor,eight 16K dynamic RAMsin socket s, rricroprocessors and D-Aconverters in sockets , two va~age regulators on a heavy -duty heatsink andlots of other ICs, capacitors. resistora , connectors and other component.Does not indude the power transformer or controis (joysticks).

___- ..- ...............CATIl A-5200 $7.50 each" 2 for $13 .50 SOLDAS-IS Fo, Pa'" Only.

POWER SUPPLIES

5Vdc3AMP~."ACDC Electronics ' 0115N3-1 New, ~ ~~Iprepped power . •supply w~h wires : :c1 .and connecto<s soldered to the Inputsand outputs. Open frame style . Regulat­ed. 4.94" X 4.03" X Z' . UL and CSAlisted . CATII PS-53 $10.00 each

12Vdc5AMPACDC Electronics II 12N5 or equiv.Input: 100-240 Vac (wired for 115 Vae)Output : 12 Vdc @ 5 amps .Open frame style . 7" X 4 314"X 3" high .Regulated . CATIl PS-125 $37 .50 each

24 Vdc 2.4 AMPPower-One Inc. IIHC-24-2.4

Input: 115r.'30 Vac (wired for 115 Vac)Outpu t: 24 Vdc @ 2.4 amps. Opne

frame style. 5.6Z' X 4.S7" X 2.50" CSAlisted. CATII PS-2424 $30.00 each

THUMB WHEEL SWITCHr'\ ~ ~ 6 Volt 1 Amp/Hour

pole 10 position r , '''. Il~: .~ '. . Japan Storage Battery Co.ledmal enc?ded C fit Il :~.., I, I PortalacsPE6V1 _ r.:l,wttches whICh "l.U ~ .., 6 Voh 1 Ah ~EfJ' .F--nte/Ioc k to make rechargeable ' "")'ip desired nurTt>eror digits . Terminates sealed011 pc pins (1 common and 10 poles) . lead-acid (ge" cel~.

;ach section measures .31" wide X.2(1' Z' X 1.635" XZ' high.ligh X .7S" deep. End plates can be add- Batteries are prepped with 5"odto form a .94" high bezel . black and red leads term inal-

CATI SWTH-9 $1.25 each ad with 2 pin connector.10 for $10.00 CATI GC-61 $4.75 each

2 END PLATES 10 for $42.50CATt SW-9EC $1.OOISet

MINIATURE TOGGLE ~.~/Cke~IC;. dRated : 3 arrps@ 120 Vac ~37 ill ~

S.P.D.T.(ON-ON) P.c.mount, AAASIZE $1.5Oeach:ATI MTS-4PC $1.00 each 1.2 volts 180 mAh10 for $9 .00 - 100 for $80.00 CA TI NCB-AAA

S.P.D. T. (ON-ON) solder lugs M SIZE $2.00 each:ATII MTS-4 $1.35 each 1.25 volts 500 mAh10 for $12 .50- 100 for $110 .00 CATI NCB-AA

I). P.D.T. (ON-ON) sold ... lugs , M SIZE $2.20 each:ATII MTS~ $1.75 each -' WITHSOLDERTABS

10 for $15.00 CATI NCB-SAA

rJ.P.D. T. (ON-ON) P.C. mount C SIZE $4.25 each:ATII MTS~PC $2.00 each 1.2 volts 1200 mAh

10 fo< $17.5O CATIINCB-C

D SIZE $4.50 each1.2 volts 1200 mAh

CATlNCB-D

CIRCLE 107 ON FREE INFORMATION CARD 93

Freedom of Choice.

GoldStar 20MHz Oscilloscope Global Specialties Protcboarde Design Station

UVP EPROM Eraser.....r·~ t r

• Erases all EPROM's • Erases 1 chip in15 minutes and 8 chips in 21 min

• UV intensity: 6800 UW/CM2

A.R.T. EPROM Programmer

• Programs all current EPROMs in the 2716 to27512 ra nge plus the X2864 EEPROM

• RS232 port · Soft war e included

PB503 $299.9!

Featu res:• Ideal for analog, digital and microprocessor circuits• Triple DC regulated power supplies, +5V. +15V. -15V• 8 logic probe circuits• Digital pulser• Function generator with sine. square. and triangle waveforms• Includes power supply. instrumentation and breadboarding

• Max Frequency 80MHz • Minimum detectablepulse: 1ons • 120KU input impedance • Max.supply voltage: ' 25V • TIL threshold: (Lo).0.8V, 0. 1V (Hi) . 2.3v ' O.2V • CMOS threshold: (Lo)30% VCC " 0% (Hi) 70%VCC , , 0%

• Compatible with TTL. DTL, RTL, HTL,HNIL. MOS and CMOS ICs. • l Mn Syncinput impedance • Pulser mode outputcurrent: 10mA • Square wave currentoutput: SmA · Audible tone

Features:• 6" rectangul ar CRT display, internal gratitude & sca le• Phase differe nce measu rements between two forms under two methods

x-y scope and Dual Trace• Two different scale probes: x1 and x10• Bandwidth from DC to 20MHz• Includes: Two 40 MHz probes. two fuses. power cord, operation manual.

schematics and block and wiring diagram• High sensitivity: 1mV/div• Two-year manufacturer's warranty

GS7020 $499.95

Jameco Logic Pulser Jameco Logic Probe

:!G£9(3@L

LP540 ;$16.95 MS104 $24.95 EPP $199.95 DE4 $79.95

EPROMs - for your programming needs

Part No. Price Part No. Price Part No. PriceTMS2516 $4.95 2764-20 $4.95 27256-15 $5.9!TMS2532 6.95 2764-25 4.75 27256-20 5.7!TMS2532-35 7.49 2764-45 4.49 27256-25 5.2!TMS2532A 7.95 2764A-20 4.25 27C256-15 6.9!TMS2564 5.95 2764A-25 3.95 27C256-20 4.9!TMS2716 5.95 27C64·15 4.49 27C256-25 4.4!1702A 4.89 27C64-25 3.49 275120TP 5.9!2708 6.95 271280TP 4.95 27512-20 7.9!2716 3.49 27128-20 6.95 27512-25 6.9!2716·1 3.95 27128-25 6.25 27C512-15 8.9!27C16 4.25 27128A-15 6.95 27C512-20 6.9!2732 4.95 27128A-20 5.95 27C512-25 6.4!2732A-20 3.95 27128A-25 4.95 27C010-15 14.9!2732A-25 3.75 27C128-15 5.95 27C010-20 13.9!2732A-45 3.49 27C128-25 5.75 68764 14.9!27C32 3.95 272560TP 4.95 68766-35 12.91

Soldering and Desoldering Stations

60 Watt Ana log Display Soldering Station • Electronic •tempe rature control from 200 0 to 878°F • Cart ridge heat-

'~ing element for a longer life of the soldering tip

XY1683.................................... ...................$69.95/~ -

30 Watt Electronic Temperature Controlled Desoldering ../Stat ion • Electronic temperature control from 2120 to842°F • Self contained high rotary vacuum pump XY999

..,

• 3.5 digit LCD with automatic polarity indication• AC/DC voltage measurement up to 500 volts• ACIOC current measurement up to 200mA• Resistance measurement up to 20MU • Con­tinuity checker with audible tone • Diode andlogic tester ' Auto/manual range and data holdfunctions · All range protection and function in­dication s

M4650 on ly : • Data hold switch , 4.5 digit

M3650 & M4650 on ly :• Also measure frequency and capac itance

Metex Digital Multimeters .

Ge nera l Specs :• Handheld. highaccuracy ' ACIDCvoltage. ACIDCcurrent, resistance,diodes, continuity,transistor hFE

• Manual ranging wIoverload protection

FAX: (415) 592-2503(415) 595-2664 DMM905 $49.95 XY999 $299.95

• Par tial Listing • Over 4000 Electronic and Computer Components in Stock!CIRCLE 114 ON FREE INFORMATION CARD

J AMECO24 Hour Order Hotline

(415) 592-8097

PROTOTYPING PRODUCTSJameco Solderles s Breadboards

JE21

Part Dim. Contact Binding M361 0 3.5 DigIt Mult,meler............... ......$59.95No. L" x W" Points Posts Price M3650 3.5 Digit Multlmeler w/Frequency &

Capacttance .............................$74.95JE 21 3.25 x 2.125 400 $4 .95 M4650 4.5 Digit wiFrequency. CapacitanceJE 23 6.5 x 2.125 830 $6.95 andData HoldSwitch...... ............$99.95JE 24 6.5 x 3.125 1.360 $12.95JE 25 6.5 x 4.25 1,660 $17.95 Handheld MultimeterJ E26 6.875 x 5.75 2.390 $22.95JE 27 7.25 x 7.5 3.220 $32.95

94

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CA Residents Add6.25%, 6.75%or 7,25% Sales Tax

Shipping - Add 5% plus $1.50Insurance(May vary acco rding to weight and shipping method)

Terms: Prices subject10 changewithout notice.Items subjectto availabilityand prior sale.Complete list of termszwarrantres is available upon request.IBM ISa regIstered tradem ark of lntemanenat BUSiness Machines

$50 .00 Minimum Order

Let usshow you what we have tooffer;call orwriteforthe latest Jameco catalog!

• Much, much more!

• Power Protection EqUipment

• Computer Accessories

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Additional items that Jameco offers:

1355 Shoreway RoadBelmo n t, CA 94 002

• Con nectors

FAX: (415) 592-2503(415) 595-2664

• Cab les

24 Hour Order Hotline(415) 592-8097

• Wide selectio n of integratedcircu its and components

• Q uality prototype and testequipment

• Comp uter kits a nd accessories

Look to Jameco.....

I v~1 1 iYI~j;I•. ..~~~

HardDrives

• Max resolution:720 x 480• Bandwidth:30MHz• Input: DB15-pin (analog)

RE9513 $449.95

Jameco 16-bit VGA Card

Conner (16-bit IDE)CP3044 40MB 35' LowProfile $469 .95CP3184 80MB3.5·HH ".".$699.95CP3104 100MB 3.5·HH""."" "" $799 .95

ADP20 Host Adapler $29.95

Relisys 14" VGAColor Monitor

l"" ~,, .

Jameco 16M Hz 80386SXDesktop Computer Kit

Includes:• 80386SX Motherboard with

2MB RAM (expandable to 8MB)• 101-key enha nced keybo ard• Multi I/O Card .• Tosh iba 1.44MB, 3.5" DSHD

floppy disk drive• Baby sized desktop case• 200 Watt power supply• DR DOS 5.0 by Digital

Research and Diagsoft'sQAP lus diagnostic software

Assemble Your own Computer Kit!

Jameco 16MHz 80386SX Desktop Computer Kit• Building your own computer provides you wit h a better unders tanding of

compon ents and their functions• In-depth assembly instructions included• Have your new computer assembled and running in an eveni ng,

using common tools• Software included• Purchase computer kits configured by Jameco or desig n your own

• Supports VGA, EGA, CGA, MOA andHercule s modes • Comes with 256KBvideo RAM upgradable to 512KB (eight41464-80) • Capable 01 640 x 480 with256 colors, 800 x 600 with 16 colors

VG2000..... .. .. .. . ....... .. ...$149.95

Integrated Circuits Miscellaneous ComponentsPart No. 1-9 10+ Part No. 1-9 10+ Pofenfiometers

74LSOO $.25 $.15 74LS154 $1.29 $1.19 Values available (insert ohms into space marked "XX"):

74 LS02 .25 .15 74LS155 .49 .39500n, 1K, SK, 10K, 20K, SOK, 100K, 1MEG

43PXX 314 Watt,15 Turn .................... ........ $.9974LS03 .25 .15 74LS 156 .49 .39 63PXX 112 Watt, 1Turn.; ..... .. .. .. .. .. ... .... .. .. .. .. .. .. ..... .. .$.8974 LS04 .25 .15 74LS157 .45 .35

Tra,nsistors And Diodes74LS05 .28 .18 74LS158 .39 .29

PN2222 ........ $.12 11N4735 ........$.25 12N4401 ...... $.1574LS06 .59 .49 74LS166 .79 .69 PN2907 .... ...... .12 2N3904 ........ ...12 1N4148 .........0774LS07 .59 .49 74 LS169 .99 .89 1N4004 .......... .10 1N751 .......... ...15 2N3055 .........6974L S08 .28 .18 74LS173 .49 .39 2N2222A ........25 C106B1 ..........49 1N270 .......... .25

74 LS10 .25 .15 74LS175 .39 .29 Switches

74LS11 .29 .19 74LS181 1.39 1.29 JMT123 SPOT, On-On (Toggle) ............................ $1.25

74LS13 .35 .25 74LS189 3.95 3.85206-8 SPST, 16-pin (OIP).................................. $1.09MPC121 SPOT,On-0ff-Dn(Toggle)...... .... ........ .. .. ...... $1.19

74L S14 .49 .39 74LS190 .59 .49 MS102 SPST, Momentary (Push-Button) ................ .$.3974LS20 .28 .18 74LS191 .59 .49 D-Sub Connectors and Hoods74LS21 .29 .19 74LS193 .69 .59 DB25P Male, 25-pin....... $.65 1DB25H Hood .......... $.3974LS27 .35 .25 74LS194 .69 .59 DB25S Female, zs- pln.. . $.75

74LS30 .28 .18 74LS221 .69 .59 LEDs

74LS32 .28 .18 74LS240 .59 .49 XC209R T1, (Red) ....... $.14 1XC556R T1 314, (Red) ... $.12

74LS38 .35 .25 74LS241 .59 .49 XC556GT1 314, (Green) ... 16 XC556Y T1314, (Yellow).. .16

74LS42 .49 .39 74LS323 2.49 2.25 IC SocketsLow Profile Wire Wrap (Gold) Level 1/2

74LS47 .85 .75 74LS541 1.09 .99 8LP ......... ..................$.11 8WW ....... ....................$.4974LS48 .85 .75 74LS590 5.95 5.75 14LP .......................... .12 14WW ...... ...................... 6574LS112 .39 .29 74LS670 .89 .79 16LP .......................... .13 16WW ......................... .. .69

74LS122 .55 .45 74LS688 2.19 1.95 24LP .......................... .19 24WW ......................... 1.0528LP ....................... ... .22 28WW ......................... 1.29

74LS123 .49 .39 81 LS95 .99 .89 40LP .......................... .28 40WW .......... ............ ... 1.7974 LS125 .49 .39 81 LS97 .99 .89 Soldertail Standard& HeaderPlug Sockets Also Available

• Customer Serv ice ·Technical Assistance- Credit Department. All Other Inquiries· (415) 592-8097 • 7AM - 4PM P.S.T.CIRCLE 114 ON FREE INFORMATION CARD 95

ADVERTISING INDEXRADIO-ELECTRONICS does not assume any responsibility for errors that may appear inthe index below.

Beckman 75

.92

.30

.29

... 7

. .. 2 1

... 89

. .. . 76

.... . 82

.. . .. 76

Viejo Publication s

U.S. Ca ble . . .

Unicorn .

Pr int Produ cts International .

People 's College ..

Radio Shack .

Parts Express .

Sta r Circuits ..

SCO Electronics . . .

189

178

182

177

194

193

78

56

.. 36

.. 93

.96

Page

... 19

.. . 80

... . . 42

. . . . . g2

... .. 17

Amazing Concepts . .

Ba nner Technical Book s

All Elect ronics

B& K Precision . . .. .

C&S Sales . . .

180 Alpha Products .

109

108 AMC Sales

107

67

Free Information Number

75 Ace Products . .

77

98

LASERS AND SCIENTIFIC DEVICES3mw Vis Red LaserDiode System Kit $159.50l aserBeam"Bounce" ListenerKit $199.50Visible Simulaled 3 Color Laser Ki!.. $44.5040 WallBurning Culling Laser Plans $20.00Hi Powered PulsedOrillingLaserPlans $20.00lto 2mwHetle VisRed LaserGun Assembled $199.00LaserLiteShow- 3 Methods Plans $20.00See in the DarkKit $299.50Electromagnetic CoilGun Ki!.. $69.50Hi Velocity CoilGun Plans $15.00Levitating OevicePlans $10.00ElectronicHypnotismTechniquesPlans $10.00

HIGH VOLTAGE AND PLASMA DISPLAY DEVICES75,000 VollOC Variable Output Lab SourceKit $149.50IonRayGun Kit, projectenergywithout wires $69.5012V/115 VAC Hi Out Neg IonGenerator Kit.. $34.50Telekinetic Enhancer/ElectricManAssembled ........ .•.$99.50Lightning DisplayGlobe Kit $54.50Worlds SmallestTesla CoilKit. $49.50250KVTable Top Tesla Coil Kit $249.501.5 MillionVollsTesla Coil Plans $20.00Jacobs Ladder- 3 Models Plans $15.00AntiGravity Generator Plans $10 .00Plasma FireSaber Assembled $59.50Dancing Plasmato Music andSoundsAssembled $79.50

HVM7KIDG3KNIG9KEMA1KLG5KBTCIKBTC3KBTC5JL3GRAlPFS20DPl 20

VRL2KLLlS1 KLHC2KLC7RUB4LGU40LLSlSD5KEMLIKMCPlLEVlEHl

. . . 42

. .. . ....... .. 86WPT Publications

Xandi Electronics.

ADVERTISING SALES OFFICE

Gernsback Publications, Inc.500·B Bi·County Blvd.Farmingdale. NY 117351-(516) 293-3000President: Larry StecklerVice President: Cathy Steckler

For Advertising ONLY516-293-3000Fax 1-516-293-3115Larry Steckler

publisherArline Fishman

advert isi ng directorDenise Haven

adve rt is ing assistantChristina Estrada

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cred it manager

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SALES OFFICES

EAST/SOUTHEASTStanley Levitan, Eastern Sa les ManagerRadio-Electronics259-23 57th AvenueLittle Neck, NY 113621-718 -428-6037. 1-516-29 3-3000Fax 1-718-225-8594

MIDWESTITexas/Arkansas/Okla .Ralph Bergen. M id west Sal es ManagerRadi o-E lectronics540 Frontage Road-5uite 339N orthfi e ld, IL 600931-708-44 6-1444Fax 1-708-446-8451

PACIFIC COAST/ Mountain StatesMarvin Green, Pacific Sal es Manag erRadio-El ectronics5430 Van Nuys Bl vd . Suite 316Van Nuys, CA 914011-818 -986-2001Fax 1-818-986-2009

191

190.. 9 1

.. .9

. . . 16

.. . 42

. . 27.26

. . ... 54

. .. .. 42

...... 29

... .. ..... 5.25

.. .. .... .. ..... 42

Heathkit

ISCET ..

Granth a m Co llege . .

Deco Indust ries . . . . . .42

Fluke Manufacturing . . . . . . .. CV2

Gene ra l Technics . .

G lobal Specialti es ..

Electronic Goldmine . . . 96

Electronics Book Club . . . . . 11.32

D&D Electronics . . 3

Contac t Ea st.

Cook 's Institute . . 18

Co mmunications Speciali sts . . . 86

CompuServe . CV4

Comma nd Productions .. 30

C henesko Products . . .

eEl . .

CIE . .

Caig Laboratories

114 .Jameco . . . . .. . . . 93.94

104 Ja n Crystals .. 18

Kin g Wholesale ....... 8g

53 MD Electronics. .. 90

93 Mark V. Elect ronics .. .9 1

61 Micro process ors Unltd . . .79

NRI Schools . . .. .. .. . . 15.85

181 O ptoelectro nics ... . . . .CV3

185

121

186

188

127

184

86

58

187

179

183

50

55

10

laroesl Horseshoe lure 'Ml havee....er seen! Make a behemauth I

srotetofriQtten everyoll! onHal­oween.onse dlnawecceuadisco strobe! Size: 2' tallx1-1/8"wide. glass tubing dia. 5/16".Opemles on :IDlOC ar<I can beused 'Nith OCIr 4KV triooer trans­lormer. (stockl 111700 10 lell).

G76 2 $7.00 EAOI

C6430

CDS CElL

~~O~Th~~.hundreds 01 '~-? ~'projects andexperiments.These change t'

their resistance withIil)hlSd~erenllypes.

G7645 for $2.00

INVERTER .aTRANSFORMER ilII1S.,.14 lea:l liansformerloruse with 5551C tocon'otl112VOC 10 2:IJoI for sIroill'lIuorescerilut:es with schematic.

N1103 $2.00 EA.1,000 fa' $ 1,500

4KV TRIGGER con.use " h any slrolle~IUOO lhalreedsa •3 Iea:I 4KV oq,cr. ,'-

N17 00 $ 1.25 FA100 lo< $80.00

* CIlIecIs All TW'Sof Radialion* Uses sensilive AVilaWiooow tubs __* ();Jerates Irarn go; Bal1ery (nol loci ) _ Q rt1 '"'"* Comes wilh PC Board, Parts, 0 "'""-~ 1]lJ

* S:~f~g:~:~'~ 19' 0@~~¢O CO. . = - =00 00

SECURITY AND PROTECTION DEVICESITM10 100,000Vollintimidator upto20' Assembled $129.50IPG70 Invisible Pain Field BlastWave Gen Assembled $74.50PSP4K PhasorSonic BlastWave Pistol Kit... : $S9.S0L1sn o IntinityXmtr, Listen in Via Phone Assembled $199.50TAnO Automatic Tel Recording Device Assembled $24.50VWPM7K 3 Mi. FM Auto Te l TransmillerKit.. . .. ..$49.50FMVI K 3 Mi. FM VoiceTransmiller Kit $39.50HDDI K Homing!TrackingBeeper Transmill erKit $49.50

EAsY ORDERING PROCEDURE TOLLFREE 1-800·221 -1705or24HRs ON 1-603-673-4730 orFAXITTO 1·603·672-5406

VisA, MC, CHECK, MO INUs FUNDs. INCLUDE 101'0 sHIPPING. OROERss100.00& UPONLY ADD $10.00.CATALOG $1.00OR FREE WITH ORDER .

(f)

gZoa:r­uui....JW

oo~a:

96 CIRCLE 188 ON FREE INFORMATION C A RD

2210AFull RangePocketSize LED,$239 .

8030Bench Portable (Fits in an attach~case) w ith ALL the Hcndl-CountertFeatures p lus More, $579.

Range SignalLow Display Display Strength Universal TCXO

Model High 8 Dlglf LED 10 DlglfLCD Bargraph Counter Option

8030 10Hz • • • ± . l pp m2.4GHz add 5125.

3000 10Hz • • • ± .2ppm2.4GHz add $ 80.

2600 1MHz • • • ± .2ppm2.4GHz add $ 80.

2210A 10Hz • ± .5pp m2.4GHz add $ 75.

1300H/A 1MHz • ± .5ppml.3 GHz add $ 75.

Sensltlvltv: <1 to <lOmV typ ical. NICad s & AC Charger/Adapter Included , Car ryCase , Antennas and Probes extra. One year pa ris & labor wa rranty on all prod ucts .

1300H/ALow Cost UltraSensitive (HF,UHF, VHF),$179.

There'snothingnew#uthaW1geve~,-youneedmoneplace. _ -, ~•

WithCompuSetve, itsallatyour fmgertips.live entertainment to interactivespace and fantasy adventures.

We've got airline schedules,so you can check out the bargainsand book your own flights online.We even have listings from over35,000 hotels.

It's not hard to get here. Toget to CompuServe, all you needis acomputer and amodem. We'llsend you everything else, includ­ing a$25.00 Usage Credit. In mostplaces you'll be able to go onlinewith alocal phone call.

To buy aCompuServe Mem­bership Kit, see your nearestcomputer dealer. To receive ourinformative brochure or to orderdirect, call 800 848-8199.

CompuServe·

access to the latestnational and interna­

tional news. And ourspecial financial filesoffer complete statistics

on over 10,000NYSE,

En!....When you become amember ofCompuServe, you join avital,active community of over 500,000friends and neighbors from all overthe world.

Small-town friendly. Wekeep in touch with electronic mailand faxes, and by posting messageson our bulletin boards.We even meetin forums to discuss everythingfrom science fiction to sharingsoftware, and to get invaluablepersonal computer softwareand hardware support. And that'sone of the best things about smalltowns: people helping people. AMEX, and OTC securities.

Big-city opportunities. But We can even trade online withwe can also shop coast-to-coast , our local discount brokers.at hundreds of natior:l,aiifmbwn And, just for fun . . .We've"stores, arid take advantage of-a.. also got games - everything fromworld-class library. We have \ :;( . lkiyja to TV-style game shows with

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