ATX DC Power Supply


This one is fairly straight forward! I do electronics projects as you might have noticed. Most of these projects use either 3.3V, 5V and on very rare occasions 12V. I would be nice to have a bench-top variable DC power supply but I’m skint! I do however have access to as many scrap computers as my heart desires. Scrap computers have power supplies in them that sometimes work… with a little modification these can be a very nice power supply to give me easy access to the voltages I want without having to faff with batteries. Obviously once I am past the prototyping phase for a project then each project will require its own power supply.

There are loads of tutorials out there on building these so I won’t go into too much detail. Here are some links to get you started.

Usual disclaimer… If you are going to take something apart and plug it into the mains then know what you are doing first! I’m not responsible for your lack of understanding even if I’ve written something down wrong!

Now go and do some reading…

…and here are some images for helpful reminders…

Basic Circuit

ATX Pin Outs

USB Cable Pin Outs

USB Internal Connector Pin Out

I decided on having two boxes for my power supply… an off-the-shelf ATX power supply and then a “converter” box that would allow you to use any ATX power supply.

Note: Having seen how easy it was to make I now wish I’d just crammed it all into one box!

This is the basic front plate I cut from ply, loooks rough at this point but gets better!
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This is my work space for this evening… sleeping child next to my regular lab prevents the use of power tools! Mad Max on the laptop.
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I brutalised the old power supply box with a jigsaw… it didn’t have to be neat, that’s what the front plate is for.
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Its alive….!!! The empty hole is for an additional fuse for the USB sockets that are going to be in the space on the left.
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Possible improvements…

  • Get my mods and the original power supply into one box.
  • Have each supply switched separately.
  • Finish adding a couple of USB ports.
  • Add an ammeter to measure the output of each supply.
  • Finish adding a couple of USB ports.