8/6/2019 Print Hobe

1/14

How to build 1.5 - 35 Volt DC Regulated Power SupplySeptember 30, 2010 - category: DC power supply

Description

Here is the circuit diagram of regulated power supply. It is a small power supply that

provides a regulated voltage, adjustable between 1.5 and 35 volts at 1 ampere. This circuit is

ready to use, you just need to add a suitable transformer. This circuit is thermal overload

protected because the current limiter and thermal overload protection are included in the IC.

Picture of the circuit:

Circuit diagram:

http://www.circuit-finder.com/categories/power-supply/dc-power-supply/page-1http://www.circuit-finder.com/categories/power-supply/dc-power-supply/page-1

8/6/2019 Print Hobe

2/14

Transformer selection chart:

Parts:

IC = LM317

P1 = 4.7K

R1 = 120R

C1 = 100nF - 63V

C2 = 1uF - 35V

C3 = 10uF - 35V

C4 = 2200uF - 35V

D1-D4 = 1N4007

Features:

Just add a suitable transformer (see table)

Great to power your projects and save money on batteries

Suitable as an adjustable power supply for experiments

Control DC motors, low voltage light bulbs,

Specifications :

Preset any voltage between 1.5 and 35V

http://www.circuit-finder.com/files/872/1-5-35-volt-dc-regulated-power-supply3_orig.gifhttp://www.circuit-finder.com/files/872/1-5-35-volt-dc-regulated-power-supply2_orig.gif

8/6/2019 Print Hobe

3/14

Very low ripple (80dB rejection)

Short-circuit, thermal and overload protection

Max input voltage : 28VAC or 40VDC

Max dissipation : 15W (with heatsink)

Dimensions : 52x52mm (2.1 x 2.1)

Technical Specifications

Input Voltage = 40Vdc max Transformer

Output Voltage = 1.5V to 35Vdc

Output Current = 1.5 Amps max.

Power Dissipation = 15W max (cooled)

Note:

It has not to be cooled if used for small powers. 28 Volt AC max is allowed for the input

voltage.

How to build Inverter Circuit For Soldering IronAugust 4, 2010 - category: DC to AC inverter

Description

Here is a simple but inexpensive inverter for using a small soldering iron (25W, 35W, etc) In

the absence of mains supply. It uses eight transistors and a few resistors and capacitors.

Transistors Q1 and Q2 (each BC547) form an astable multivibrator that produces 50Hz signal.

The complementary outputs from the collectors of transistors Q1 and Q2 are fed to pnp

Darlington driver stages formed by transistor pairs Q3-Q5 and Q4-Q6 (utilising BC558 and

BD140).

The outputs from the drivers are fed to transistors Q7 and Q8 (each 2N3055) connected for

push-pull operation. Use suitable heat-sinks for transistors Q5 through Q8. A 230V AC

primary to 12V-0-12V, 4.5A secondary transformer (T1) is used. The centre-tapped terminal

of the secondary of the transformer is connected to the battery (12V, 7Ah), while the other

two terminals of the secondary are connected to the collectors of power transistors T7 and

T8, respectively.

http://www.circuit-finder.com/categories/power-supply/dc-to-ac-inverter/page-1http://www.circuit-finder.com/categories/power-supply/dc-to-ac-inverter/page-1

8/6/2019 Print Hobe

4/14

When you power the circuit using switch S1, transformer X1 produces 230V AC at its primary

terminal. This voltage can be used to heat your soldering iron. Assemble the circuit on a

generalpurpose PCB and house in a suitable cabinet. Connect the battery and transformer

with suitable current-carrying wires. On the front panel of the box, fit power switch S1 and a

3-pin socket for connecting the soldering iron. Note that the ratings of the battery, transistors

T7 and T8, and transformer may vary as these all depend on the load (soldering iron).

Circuit diagram:

Parts:

P1-P2 = 47K

R1-R2 = 1K

R3-R4 = 270R

R5-R6 = 100R/1W

R7-R8 = 22R/5W

C1-C2 = 0.47uF

Q1-Q2 = BC547

Q3-Q4 = BC558

Q5-Q6 = BD140

Q7-Q8 = 2N3055

SW1 = On-Off Switch

T1 = 230V AC Primary 12-0-12V

4.5A Secondary Transformer

B1 = 12V 7Ah

http://www.circuit-finder.com/files/799/inverter-circuit-for-soldering-iron1_orig.gif

8/6/2019 Print Hobe

5/14

How to build InverterNovember 8, 2010 - category:DC to AC inverter

Description

Have you ever wanted to run a TV, stereo or other appliance while on the road or camping?

Well, this inverter should solve that problem. It takes 12 VDC and steps it up to 120 VAC.

The wattage depends on which tansistors you use for Q1 and Q2, as well as how "big" a

transformer you use for T1. The inverter can be constructed to supply anywhere from 1 to

1000 (1 KW) watts.

Circuit diagram

Parts:

C1, C2 68 uf, 25 V Tantalum Capacitor

R1, R2 10 Ohm, 5 Watt Resistor

R3, R4 180 Ohm, 1 Watt Resistor

D1, D2 HEP 154 Silicon Diode

Q1, Q2 2N3055 NPN Transistor (see "Notes")

T1 24V, Center Tapped Transformer (see "Notes")

MISC Wire, Case, Receptical (For Output)

Notes:

http://www.circuit-finder.com/categories/power-supply/dc-to-ac-inverter/page-1http://www.circuit-finder.com/categories/power-supply/dc-to-ac-inverter/page-1http://www.circuit-finder.com/files/152/inverter_orig.gifhttp://www.circuit-finder.com/categories/power-supply/dc-to-ac-inverter/page-1

8/6/2019 Print Hobe

6/14

Q1 and Q2, as well as T1, determine how much wattage the inverter can supply. With

Q1,Q2=2N3055 and T1= 15 A, the inverter can supply about 300 watts. Larger transformers

and more powerful transistors can be substituted for T1, Q1 and Q2 for more power.

The easiest and least expensive way to get a large T1 is to re-wind an old microwave

transformer. These transformers are rated at about 1KW and are perfect. Go to a local TV

repair shop and dig through the dumpster until you get the largest microwave you can find.

The bigger the microwave the bigger transformer. Remove the transformer, being careful

not to touch the large high voltage capacitor that might still be charged. If you want, you

can test the transformer, but they are usually still good. Now, remove the old 2000 V

secondary, being careful not to damage the primary. Leave the primary in tact. Now, wind

on 12 turns of wire, twist a loop (center tap), and wind on 12 more turns. The guage of the

wire will depend on how much current you plan to have the transformer supply. Enamel

covered magnet wire works great for this. Now secure the windings with tape. Thats all

there is to it. Remember to use high current transistors for Q1 and Q2. The 2N3055's in the

parts list can only handle 15 amps each.

Remember, when operating at high wattages, this circuit draws huge amounts of

current. Don't let your battery go dead :-).

Since this project produces 120 VAC, you must include a fuse and build the project in

a case.

You must use tantalum capacitors for C1 and C2. Regular electrolytics will overheat

and explode. And yes, 68uF is the correct value. There are no substitutions.

This circuit can be tricky to get going. Differences in transformers, transistors, parts

substitutions or anything else not on this page may cause it to not function.

Electronic Cricket Circuit Diagram

8/6/2019 Print Hobe

7/14

When the Push Switch S1 is pressed momentarily, the Astable operates and all the LEDs

run very fast sequentially. When S1 is released, any one of the LED stands lit which

indicates the status of the match. For example, if LED D7 remains lit, it indicates Sixerand if LED 8 remains lit, it indicates Catch out.

Label each LED for its status as shown in the diagram. Pressing of S1 simulates Bowling

and Running LEDs indicates running of Batsman.

How to build Fire Alarm Using Thermistor

October 4, 2010 - category:Temperature sensor

Description

In this fire alarm circuit, a Thermistor works as the heat sensor. When

temperature increases, its resistance decreases, and vice versa. At normaltemperature, the resistance of the Thermistor (TH1) is approximately 10 kilo-

ohms, which reduces to a few ohms as the temperature increases beyond

100 C. The circuit uses readily available components and can be easily

constructed on any general-purpose PCB.

Circuit Diagram:

http://www.circuit-finder.com/categories/sensor/temperature-sensor/page-1http://electroschematics.com/wp-content/uploads/2010/10/Electronic-Cricket-Circuit.pnghttp://www.circuit-finder.com/categories/sensor/temperature-sensor/page-1

8/6/2019 Print Hobe

8/14

8/6/2019 Print Hobe

9/14

transistor Q1 via diode D2 and resistor R3. Capacitor C1 charges up to the positive voltage

and increases the on time of alarm. The higher the value of capacitor C1, the higher the

forward voltage applied to the base of transistor Q1. Since the collector of transistor Q1 is

connected to the base of transistor Q2, transistor Q2 provides positive voltage to reset pin 4

of IC1. R5 is used such that IC1 remains inactive in the absence of positive voltage. D2 stops

discharging of capacitor C1 when the Thermistor connected to the positive supply cools down

and provides a high-resistance (10k) path. It also stops the conduction of Q1. To prevent the

Thermistor from melting, wrap it up in mica tape. The circuit works off a 6V-12V regulated

power supply. D1 is used to indicate that power to the circuit is switched on.

How to build On Off Touch Switch CircuitSeptember 30, 2010 - category: Touch sensor

Description

The modern mechanic switches are improved concerning of old technology. We need however

many times to replacement some old switch or to check currents bigger than the durability of

certain switches or simple we need something with modern appearance. For he and different

reasons is essential the up circuit. It is simple in the manufacture and the materials that use

they exist everywhere.

Circuit diagram:

Parts:

R1 = 3.3M

R2 = 3.3M

R3 = 10K

R4 = 1K

C1 = 10nF-63V

D1 = 1N4007

http://www.circuit-finder.com/categories/sensor/touch-sensor/page-1http://www.circuit-finder.com/files/869/on-off-touch-switch-circuit_orig.gifhttp://www.circuit-finder.com/categories/sensor/touch-sensor/page-1

8/6/2019 Print Hobe

10/14

D2 = Red LED

Q1 = BC547

IC1 = NE555

RL1 = 12V Relay

Circuit Operation:

This circuit is based on the well known timer IC 555 (IC1), which drives a relay of which the

contacts play the role of switch. The metal surfaces can have what form we want, but it

should they are clean and near in the circuit. In order to it changes situation it suffices touch

soft somebody from the two plates. Plate MP1 in order to the contacts of RL1 close [ON], or

plate MP2 in order to the contacts of RL1 open [OFF]. The current that RL1 will check

depended from his contacts. The Led D2 turns on when the switch they are in place ON and

the contacts of RL1 closed. Two small pieces of metal can be used instead of MP1 MP2.

Because MP = Metal Plate.

6V to 12V Converter

This inverter circuit can provide up to 800mA of 12V power from a 6V supply. Forexample, you could run 12V car accessories in a 6V (British?) car. The circuit is simple, about75% efficient and quite useful. By changing just a few components, you can also modify it fordifferent voltages.

Circuit diagram

PartsR1, R4 2.2K 1/4W ResistorR2, R3 4.7K 1/4W ResistorR5 1K 1/4W ResistorR6 1.5K 1/4W Resistor

http://www.diy-electronic-projects.com/projects/61/bigs/6_12conv.gif

8/6/2019 Print Hobe

11/14

R7 33K 1/4W ResistorR8 10K 1/4W ResistorC1,C2 0.1uF Ceramic Disc CapacitorC3 470uF 25V Electrolytic CapcitorD1 1N914 DiodeD21N4004 DiodeD3 12V 400mW Zener DiodeQ1, Q2, Q4 BC547 NPN TransistorQ3 BD679 NPN TransistorL1 See NotesMISC Heatsink For Q3, Binding Posts (For Input/Output), Wire, Board

Notes1. L1 is a custom inductor wound with about 80 turns of 0.5mm magnet wire around a toroidalcore with a 40mm outside diameter.2. Different values of D3 can be used to get different output voltages from about 0.6V to around30V. Note that at higher voltages the circuit might not perform as well and may not produce asmuch current. You may also need to use a larger C3 for higher voltages and/or higher currents.3. You can use a larger value for C3 to provide better filtering.4. The circuit will require about 2A from the 6V supply to provide the full 800mA at 12V.

Circuit diagram

8/6/2019 Print Hobe

12/14

LIE DETECTORThis circuit detects the resistance between your

fingers to produce an oscillation. The detection-

points will detect resistances as high as 300k and

as the resistance decreases, the frequency

increases.

Separate the two touch pads and attach them to theback of each hand. As the subject feels nervous, he

will sweat and change the frequency of the circuit.

The photos show the circuit built on PC boards with

separate touch pads.

ROBOT-1

8/6/2019 Print Hobe

13/14

A simple robot can be made with 2 motors and two light-detecting circuits, (identical to the circuitabove). The robot is attracted to light and when the light dependent resistor sees light, itsresistance decreases. This turns on the BC547 and also the BC557. The shaft of the motor has arubber foot that contacts the ground and moves the robot. The two pots adjust the sensitivity ofthe LDRs. This kit is available from Velleman as kit number MK127.

8/6/2019 Print Hobe

14/14

This simple programmer will accept any device that's supported by software (eg, IC-Prog 1.05by Bonny Gijzen at www.ic-prog.com). The circuit is based in part on the ISP header describedin the SILICON CHIP "PIC Testbed" project but also features an external programming voltagesupply for laptops and for other situations where the voltage present on the RS232 port isinsufficient. This is done using 3-terminal regulators REG1 & REG2. The PIC to be programmedcan be mounted on a protoboard. This makes complex socket wiring to support multipledevices unnecessary. 16F84A, 12C509, 16C765 and other devices have all been usedsuccessfully with this device.

Circuit diagram:

Simple Universal PIC Programmer Circuit Diagram

http://www.blogger.com/www.ic-prog.comhttp://www.extremecircuits.net/2010/05/simple-universal-pic-programmer.htmlhttp://www.extremecircuits.net/2010/05/simple-universal-pic-programmer.htmlhttp://www.blogger.com/www.ic-prog.comhttp://www.extremecircuits.net/2010/05/simple-universal-pic-programmer.html