Saturday, January 11, 2014

Variable Power Supply Using LM723

Using LM723 regulator can be designed a very simple variable power supply circuit which can provide a maximum current up to 2A and a variable voltage between 2 and 25 volts.This 25v variable power supply is designed using a LM723 regulator and a few common electronic components.Input voltage must be between 28 and 37 volts. Mj3000 transistor must be mounted on a radiator for heat dissipation.

LM723 Variable Power Supply Circuit diagram


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Friday, January 10, 2014

High Current Power Supply

Since my page was first posted, I have received a number of emails asking about a high current power supply. I looked around, but couldnt find one that was suitable. So, I designed this. It is a linear supply, which might have a few of you rolling your eyes, but it takes very few parts, is simple to build and can supply huge currents

High Current Power Supply Circuit diagram :

High Current Power Supply-Circuit diagram

Parts Table :

Part Total Qty Description
R1 1 680 Ohm 1/4 Watt Resistor
C1 1 20,000 - 50,000uF 20-40 Volt Capacitor   
C2, C3 2 100uF 50 Volt Capacitor
C4 1 0.1uF 50 Volt Capacitor
C5 1 0.01uF 50 Volt Capacitor
D1 1 Zener Diode (See Notes)   
Q1 1 2N3055 Or Other (See Notes)
T1 1 Transformer (See Notes)
BR1 1 Bridge Rectifier (See Notes)
S1 1 SPST 250 VAC 10 A Switch
MISC 1 Case, Line Cord, Heatsink For Q1, Binding Posts For Output

Notes :

  1. D1 should be rated at about one volt higher than then desired output of the supply. A half watt diode will do.
  2. Q1 can be a transistor similar to the 2N3055. I chose the 2N3055 for its availability and power handling (150 watts).
  3. T1 should be about 5 volts higher than the desired output of the supply, and rated for about one amp more of current. The voltage overhead is required by the regulator section. The extra current is to keep the transformer from over heating.
  4. The choice of BR1 will depend on the voltage and current of your transformer. The rectifier should be rated for 50 volts more than the transformer, and 5 amps more than the transformer.
  5. The value of R1 will be smaller when supplying high currents. Expiriment until you get what you need.
  6. Heatsink and fans are absolutely necessary!
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Mains Pulser

The pulser is intended to switch the mains voltage on and off at intervals between just under a second and up to 10 minutes. This is useful, for instance, when a mains-operated equipment is to be tested for long periods, or for periodic switching of machinery. Transformer Tr1, the bridge rectifier , and regulator IC1 provide a stable 12V supply rail for IC2 and the relay. The timer is arranged so that the period-determining capacitor can be charged and discharged independently. Four time ranges can be selected by selecting capacitors with the aid of jumpers. Short-circuiting positions 1 and 2 gives the longest time, and short-circuiting none the shortest.

Mains Pulser Circuit diagram:



In the latter case, the 10µF capacitor at pins 2 and 6 of the timer IC determines the time with the relevant resistors. The value of this capacitor may be chosen slightly lower. The two preset potentiometers enable the on and off periods to be set. The 1k resistor in series with one of the presets determines the minimum discharge time. The timer IC switches a relay whose double-pole contacts switch the mains voltage. The LEDs indicate whether the mains voltage is switched through (red) or not (green). The 100mA slow fuse protects the mains transformer and low-voltage circuit. The 4 A medium slow fuse protects the relay against overload.

Source :   http://www.ecircuitslab.com/2011/05/mains-pulser.html
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Build a Room Ioniser Circuit Diagram

This is a voltage multiplier circuit acting as an Room Ioniser Circuit Diagram. Its calculated to feed 220V from mains and the output is about 6KV. Caution should take with the circuit as can be dangerous due to mains. You can place a needle at the output 3cm long. Even you disconnect from mains, capacitors can be dangerous so make sure to discharge them by shorting their pins before you touch the circuit with hands.

Room Ioniser Circuit Diagram

Build a Room Ioniser Circuit Diagram
 
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