Introduction: Bench Power Supply Using PC Power Supply

Picture of Bench Power Supply Using PC Power Supply

This comes in handy for testing most DC circuits that use 1.2 VDC up to 20 VDC. Total cost was less the $20. I know that this doesn't have the best looking wiring on the inside but I rushed placing components because I really needed it do for testing components at work.

Warning: In this project you wont be inside the PSU but if you do open it make sure to give a day or to unplugged for the capacitors to discharge. The wires coming out of the PSU only have 3 Amps so besides a quick shock there wont issues.

Step 1: Supply's

1. Tape
2. Screw Driver
3. Computer PSU
4. Cable
5. Soldering Iron
6. Drill & Bits
7. Wire cutters
8. Wire strippers
9. Volt Meter
10. Test leads with patch banana clips (red & Black)

superglue or epoxy

Step 2:

Step 3: Circuit Components

Picture of Circuit Components

• Switch
• 2 LEDs of any color (Red and Green)
• 2 Resistors 330 OHM
• Heat Shrink Tubing
• External Enclosure
• Drill and Bits
• LM317, LM338K, or LM350T Voltage regulator
• 100nF Capacitors (ceramic or tantalum)
• 1uF Capacitors Electrolytic
• 1N4001 or 1N4002 Power Diode
• 120 Ohm resistor
• 5k Ohm variable resistor
• Binding Posts

ATX Power Supply Extension Cable ( comes included with most PSU)

Step 4: Circuit

Picture of Circuit

I tested the circuit on a bread board first.

note: the voltage regulator can have different pins from what is shown. make sure to look up the stats sheet.

Step 5: Future Improvements.

Add a USB port to it by connecting it to the 5 DCV.

Add a cigarette lighter to the 12 DCV if I can get it to fit inside case.

a built in voltage meter.

Step 6:


lhj734017 (author)2014-07-01

where in the schematic is the diode supposed to go? I only see the location of the LEDs. I see the diode attached to one of the legs of the regulator chip in the picture but im having trouble following your wiring

klilly1 (author)lhj7340172014-07-01

Thanks for noticing that it goes in between the output leg and + 12 VDC I'll edit that when I get a chance.

jedii72 (author)2014-05-31

Cool project. Question: I was told that when you combine the + and - 12V, yes you get a loss, but you should not sure any of the Outs (+5 or +3) at the same time because the phase difference the 12Vs are using simultaneously will mess up the Vout. Have you experienced any such problem? Note: it was an electrical engineer trying to explain that to me, but since I'm not an engineer I may have lost something in the translation so my understanding my be wrong.

klilly1 (author)jedii722014-05-31

thanks this is all DC voltage so the phase will be constant also you do get voltage loss because the regulator needs to use some of it to work. I hope that helps. I could also explain why I use a negative and a positive voltage to get double the voltage.

mstone25 (author)2014-05-14

Ah sorry ignore my comment, I see you are using + and - 12V. :)

klilly1 (author)mstone252014-05-15

yeah I'm using +12 and -12 the and the most voltage I get out of it is about 20.1 VDC because of the loss.

mstone25 (author)2014-05-14

You do know that you can't get higher Vout than Vin don't you? In fact you'll lose about 1.6V across the regulator so best you'll get is around 10.5V with a Vin of 12V

About This Instructable




Bio: US Army Veteran, Maker and Tinkerer- Makers make things without tinkering or following instructions on a worksheet to complete a project is less about tinkering ... More »
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