Dual Adjustable Power Supply

  • Rajkumar Sharma
  • 49249
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  • medium
  • Tested

004_PIC

This project is a solution to power up most of devices or projects requiring dual (+/-) adjustable power supply.

Description

The circuit is based on LM317 positive and LM337 negative voltage regulators. LM317 series of adjustable 3 terminal regulator is capable of supplying in excess of 1.5A over a  1.2V to 30V DC output range, due to TO3 package of  IC and large heat sink the power supply can handle maximum load  current.

  • Output: +/- 1.2 to 30V DC
  • Output Current: 1.5Amps
  • Supply Input: 24V-0-24V AC, 2Amps Center tape Transformer
  • CN1: Transformer Connections
  • CN3: +/- Dual Supply Outputs
  • P1: Positive Voltage Adjust
  • P2: Negative Voltage Adjust
  • D1: Positive Power Indicator
  • D2: Negative Power Indicator

Schematic

004_Schematic

Parts List

004_BOM

PCB

Downloads

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Benjie

can the transformer be replaced with a higher current rating like 3 or 5 amps?

brirky

Can I use this two 220VAC/12VAC halogen transformer serial connected?
http://www.ebay.es/itm/201209984483?_trksid=p2060353.m1438.l2649&var=500403606005&ssPageName=STRK%3AMEBIDX%3AIT
If they have 12VAC 60W output each, I should get 24VAC 120W 5A output.
Or this one :
http://www.ebay.es/itm/361038813028?_trksid=p2060353.m1438.l2649&var=630376295270&ssPageName=STRK%3AMEBIDX%3AIT
Connected directly to the output of the diode bridge.
Which one is the best option?
Thanks

Demetrio M. Olarte

How can I make the output voltage be 0-30 volts?

saranya

thankyou

Shivenarayan yadav

Very good work

Romar

what would be the output voltage range if i only used a 15 – 0 – 15 transformer? thank you. great work by the way, neat and nice.

Jommy

Please I need to implement this as a 12V, 2A dual output unit what modifications do I need to make.

Riza

why not LM317T or LM337T ?

Ritesh

I used 24-0-24V, 1Amp Transformer as i needed max 1 Amp. The problem with the circuit is, without any load connected o/p is 1.5V to ~33V at positive side and the same with negative side ( obviously with -ve values). (after measuring on multi-meter) But, as i connect any load the +ve side provides stable and proper voltage supply. However, on -ve side it just stuck around 1.5V to 3V. I checked for any short circuits, bypass capacitors, etc. And every thing is seems good. But, only at pin’s of LM337 might be problem . so, i tried with LM905 and the same thing happens with it. no voltage at output when load is connected.
Please, let me know what’s happening? and how to make corrections?
Thanks in Advance…

tianqiu

What is 220E?

tianqiu

Can i change the bridge rectifier into 4 silicon diode (1N4007)?

SARATH SIVADAS

please add pcb layout in pdf format

Yhan

why the starting voltage is 1.2v ? how can i get 0 volts in the start ?

Walter

Because LM317/337 need reference voltage of 1.25V.
It’s possible to go to zero but the design need to change.

Waqas Farooqui

Hi, I just made this circuit but I’m having problem in the – ve voltage section. The positive voltage can be regulated but the negative side voltage has no impact

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