BELL SYSTEM PRACTICESSW. Bell Tel. Co.

SECTION 463-2l0-900SWIssue A, August, 1977

LSI-12 AND LSI-24 LINESTATUS INDICATOR

IDENTIFICATION AND INSTALLATION

1. GENERAL

1.01 This Section furnishes the identifica-tion, ordering, installation and mainte-

nance information for the Associated Instru-ment Manufacturing Corporation Line StatusIndicators LSI-12 and LSI-24.

2. IDENTIFICATION

2.01 The LSI indicator (Exhibit 1) is avail-able with capacities for monitoring

12 lines on the LSI-12 and 24 lines on theLSI-24. Both line sizes use the same sizecabinet.

2.02 Overall dioensions: approximatemeasurements of the Line Status Indi-

cators are as follows:

Approximately 5 inches wide by 5 incheshigh by 5 inches deep at the base taperedto 3 inches deep at the top.

2.03 Application: the LSI-12 and LSI-24models of the Line Status Indicator,

are intended for non-key systems which arecapable of offering call pick-up service.It provides a means of visually determiningline status - off hook or ringing - as wellas providing common-audible without the useof key equipment or incandescent lamps.These Line Status Indicators are compatiblewith all types of PBX equipment except theDimension Custom Telephone Set.

\,2.04 Power: power is furnished using a

20l2B-50 transformer and a customerprovided l17V/60Hz outlet not under controlof a switch.

2.05 Line Status Indicator operation: theLSI-12 and LSI-24 indicator connects

in series with the T and R leads of linesto be monitored and indicates the status ofthese lines. There is a Light EmittingDiode (LED) associated with each of the moni-tored lines. This LED is off when the lineis idle, on when the line is off-hook andflashes at 20Hz rate when the line isringing. In addition, a common audible toneinside the LSI will sound when any line beingmonitored is ringing. The 20Hz lamp rateand audible signal are activated only whenringing voltage is actually being applied;they are not activated during the silentintervals. Therefore, the LSI-12 and LSI-24indicators will provide the same distinctiveringing patterns provided to stations inthe DIMENSION PBX (CSS20l).

2.06 When a ringing station is to be answeredby someone other than the station user,

the answering location can dial a call pick-upcode. When the pick-up code is dialed, thecall will be transfered to the attendantsphone and the lamp assocaited with the atten-dants line will light but the other lamp willgo out. In the case where more than one phoneis being rung, the determination of which callis answered us made by seeing which LED stopsflashing. If there are dial pulse phonesin the group, the pulse will be indicatedby the lamp but will be brighter and muchfaster than the ringing pulse.

2.07 These items may be ordered thru WesternElectric Company via the Order Invoice

Plan.

(Qty) Indicator, Line Status LSI-12 (Color)

NOTICENot for use or disclosure outside the

Bell System except under written agreement.

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SECTION 463-210-900SW

(Qty) Indicator, Line Status LSI-24 (Color)

The available colors are: beige (60),black (03), green (51), yellow (56),white (58), blue (62), red (53) andivory (50).

(Qty) Transformer, 2012B-50

3. INSTALLATION

3.01 Terminate A25B connector cables onconnector blocks as shown in Exhibits

2 and 3. Tip and ring polarity must bemaintained when terminating line statusindicator leads to incoming CO tipsand rings. Lead assignments for LSI-12unit are shown in Exhibit 4 on Connector -1.Connections for LSI-24 unit are shown inExhibit 4 on Connections 1 and 2.

3.02 Connect the transformer leads toconnecting block as shown in Exhibit

4 using D station wire.

3.03 The audible tone is adjusted by turningthe potentiometer that is mounted

on the metal base of the LSI unit.

NOTE: Avoid locating Line Status Indicatorin direct sunlight or areas of highillumination.

4. MAINTENANCE

4.01 Maintenance of the LSI-12 and LSI-24Line Status Indicator is limited to

the replacement of defective LED units andadjustment of the volume of the audible tone.The audible tone can be adjusted by turningthe potentiometer that is mounted on themetal base of the LSI. The indicator lamps(LEDs) are mounted in sockets that permitreplacement in the field. Replacement lampscan be ordered as follows:

(10) Indicator Lamp, LED

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Order from:

Associated Instrument Mfg. Corp.2313 Brun StreetHouston, Texas 77019

4.02 Do not attempt any maintenance otherthan described in 4.01. If Line Status

Indicator becomes defective, replace it withone known to be working properly and returndefective indicator to the Western ElectricService Center for repair.

5. CIRCUIT DESCRIPTION

5.01 Each line entering the Line StatusIndicator has its own isolated circuit

to indicate the status. Each circuit con-sists of a light emitting diode and anoptoelectronic photocoup1er plus severalother components that have a supportive role.(See Exhibit 5.)

5.02 The LED is used to provide the indicat-ing light for each line. The LED chosen

by Associated Instrument Mfg. Corp. for usein the Line Status Indicator is red and hasa typical forward voltage drop of 1.8 voltsD.C. at 25 mA thus providing an averagepower dissipation of .045 watt.

5.03 The optoelectronic photocoup1er isthe main component in the ring detector

portion of each circuit. It consists of aneon lamp coupled to a photoconductor. Theneon lamp is connected across the tip andring sides of the line. The talk signal,being either twenty-four or forty-eightvolts, has no effect at all on the neonlamp. However, when the ringing signa1 isapplied, the neon ionizes and light shineson the photoconductor changing the resistancefrom approximately two megohms to approximatelytwo thousand ohms.

SECTION 463-2l0-900SW

5.04 The photoconductors from each line,either twelve or twenty-four, are

placed in parallel with each other, thus pro-viding electrical isolation of the individuallines but still furnishing a common audible.

5.05 The tone itself is achieved by usinga 555 clock as an astable multivibrator

and using this to drive a small speaker. Thephotoconductive elements of the photocouplerare then connected between Vcc and the resetpin of the 555. (See Exhibit 6.)

5.06 The talk signal lights the LED buthas no affect on the neon lamp. The

ringing machine provides a high enough voltageacross the neon lamp to induce breakdown andthe lamp lights. When any of the lamps light,the photoconductor will decrease to abouttwo thousand ohms thus putting a positiveinput on the rest pin of the 555 clock causingit to oscillate.

l ,...--...,

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SECTION 463-210-900SW

EXHIBIT 1

LSI-12 and LSI-24 Line Status Indicators

Page 4

--------

EXHIBIT 2

SECTION 463-2l0-900SW

Method of Connecting Line Status Indicator Using 66-Type Blocks

Conn. Block

ToCO

Conn. Block

Conn. Block

ToTelSet

ToLS1

----- --------------

Page 5

SECTION 463-2l0-900SW

ToCO

EXHIBIT 3

Method of Connecting Line Status Indicator Using 88-Type Blocks

Conn.Block

~~IIxIx

XIXXXXI

XI_X

Bridging Block

XI ] To' Tel.

IXI SetXIxl

----------

1 ToLSI

\)

LXI X

XI XI

X XXI XIXI XI

XI XI Conn.[ C [_XI _XI _:: Blo'k

L----------------x/---

xl

X

XX

XX

Page 6

X

XXX

X

SECTION 463-210-900SW

EXHIBIT 4

CONNECTIONS FOR LSI-12 AND LSI-24 LINE STATUS INDICATORS

26 ~] 26 Tr]1 127 T1 Line 1 27 Line 132 R1 2 R1

28 Tr] 28 Tr]3 329 Line 2 29 Line 144 R1 4 R1

30TrJ

30 T~]5 531 Line 3 31 Line 156 R1 6 R1

32 Tr] 32 Tr]7 733 Line 4 33 Line 168 R1 8 R1

34 Tr] 34 Tr]9 935 Line 5 35 Line 1710 R1 10 R136 T~] 36 Tr]~ 11 1137 Line 6 37 Line 1812 R1 12 R138 Tr] 38 Tr]13 1339 Line 7 39 Line 1914 R1 14 R140 T~] 40 T~]15 1541 Line 8 41 Line 2016 R1 16 R142 Tr] 42 Tr]17 1743 Line 9 43 Line 2118 R1 18 R144 Tr] 44 Tr]19 1945 Line 10 45 Line 2220 R1 20 R146 Tr] 46 Tr]21 2147 Line 11 47 Line 2322 R1 22 R148 T~] 48 Tr]23 2349 Line 12 49 Line 2424 R1 24 R1

~ 50 AC~J To 2012B-50 5025 AC2 Transformer 25

CONNECTOR - 1 CONNECTOR - 2

---'"

Page 7

SECTION 463-210-900SWEXHIBIT 5

LINE CIRCUIT

I-------------------~1 _ - I

I II LED :

T

Page 8

lN4002

220KCl

C

To ToneCKT

lOOK

R ~----------------L---------------+_---------Rl1

II I1 I1 J

EXHIBIT 6

TONE CIRCUIT

SECTION 463-210-900SW

100uf

1N4744A 1Ke lOOK JL 8 .ri

AC1

8 7 6 5

555Clock

2 3 4

~ .01 100u£AC2100.fl.

10K .JL

C

To Line CKT

C1

Page 99 Pages