DIY Power Supply

Today we take a look at re-purposing a computer power supply.

If you’re anything like me you probably have a couple of computer power supplies lying around your home. I collect mine because I like having a replacement power supply on hand just in case the one inside one of my computers stops working. But the fact is, PC power supplies tend not to die, which recently got me looking for other ways I can use them. What I found to be a good use for them is to use them as bench top power supplies.

Here is the end result. A small box that sits on top of my desk. It has 4 posts: Ground, 3.3 volts, 5 volts and 12 volts.

I looked at many tutorials on converting computer power supplies into bench top supplies. All of them attach the banana posts to the power supply case itself, which I really don’t like. It means the power supply has to be on top of the desk in order to be used.  My desk tends to be cultterd with many things as it is. I decided to have a small box that just holds the banana posts. The box sits on my desk and has wires running to the power supply, which I keep on the floor. This way, the power supply is just as useful but now takes up a lot less space on my desk.

The box with the banana posts also has  a toggle switch and an LED. The Toggle switch turns the power supply on and off. The LED glows when the power supply is on.

I modified the computer power supply to use my multi-core cable instead of the standard power supply cables. The cables have been cut off and instead the chassis has been fitted with a plug. The plug has 7 pins, which are used for 12v, 5v, 3.3v, Switch, and the remaining three pins for Ground. Each wire of the power supply has a specific voltage. Here are the wires I soldered to the plug:

RED wire – 12 volts
ORANGE wire – 5 volts
YELLOW wire – 3.3 volts
GREEN wire – Switch
BLACK wire – Ground


Before and after. On the left is what the power supply used to look like. On the right is what it looks like now after I cut down the wires and installed the connector.

7 pin jack7 pin plug

Here is a close up of the female and male part of the connector. They where bought purchased from The power supply wires used to come out of that hole, now there is a plug mounted there.  Lucky, the hole in the power supply case turned out to be just the right size.

Here is what the inside of the breakout box looks like. The switch on the black box turns the main power supply on and off. The power supply has this feature built in already. All that was needed to be done was to wire the green wire to the Switch along with Ground. When the Green wire is connected to Ground, the power supply turns on. When the Green wire is left disconnected, the power supply turns off. Normally the motherboard does this, but by connecting the wire to the Switch I can turn the power supply on from the black breakout box without having to bend down and turn on the Switch on the power supply itself.

If you’re thinking about building your own power supply out of a computer supply I recommended this tutorial.

Leave a Reply

Your email address will not be published.