Reuse - Re-purpose an Old Computer Power Supply


Introduction: Reuse - Re-purpose an Old Computer Power Supply

Old computer power supplies are a great resource for ham radio gear, CB radios, chargers, or any other item that needs a regulated 12 volt source.  Many of these older power supplies do not have an on/off switch on the unit.  By tapping the green wire and any of the black wires on that connection plug that goes to the motherboard a standard switch can be wired in.  

Another benefit is that these supplies have several wired 12 volt and 5 volt outputs.  A custom supply with USB plugs and several cigarette-style receptacles could be constructed.

Be safe.  Have fun!

Thanks for watching.



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    7 Discussions

    Just a note to let you know I have added this instructable to the collection:
    Encyclopedia of ATX to Bench Power Supply Conversion
    Take a look at about 70 different approaches to this project.

    1 reply

    I used one for power for my 1/4 inch impact cordless drill. The batteries wouldn't recharge and i loved this drill, so I isolated the 12v, gutted the battery, wired it in, and I have a corded cordless, ha, ha. Seriously it works, though not as fast because it is an 18v drill, but gets the job done.

    I read a book on repairing PCs and it had all sorts of dire warnings about the danger of shock in opening these power supplies. I had a couple fail, and eventually opened them. I was careful to short out the capacitors with a well-insulated screwdriver, and had no problems. I harvested parts I thought I might one day use. Of course my power supplies had failed and were not really useful any longer, unless an obvious fault might be found and repaired. Thank you for your Instructable.

    1 reply

    Ah the good old no user serviceable parts inside warning. I'm not a typical user. I like tools so I don't like to burn my screwdrivers. If I need to bleed a cap, and all of the high voltage caps in a PC PSU are circuit bled anyways, but if I do need to bleed a cap I use a bleeder resistor to do it. It saves my tools, and the capacitor. PC PSUs have some high current diodes in them. They look like TO-220 or TO-3P power transistors but there is a pictogram of 2 diodes facing each other on them. I used one in this project as a diode

    In the schematic I subbed it for the LT10A04 The diode out of the PSU was rated for 50 amps or something silly like that. You can just see it in this picture it is the topmost left hand part on the circuit board that looks like a power transistor. Between the black and the red wires.

    That is the power supply I use for my CNC project. It is a lot nicer than some junky old PC PSU. About the handiest thing I've found with PC PSUs is the metal case itself. I use those more than anything else I've ever salvaged out of a PC PSU. I guess the wire is handy too. It is nice stranded hookup wire. Sometimes I get a decent heat sink out of a PC PSU, most of the time they're those aluminum sheet heat sinks and they're pretty terrible. Other than that the rest of it I've never found much use for myself.

    Thanks for your comments and taking a look Phil. Yeah, some electronic parts I don't like opening up and power supplies fall into that category. I've been zapped once or twice from charged capacitors. Not fun and pretty serious stuff. This little video was to show that a power supply doesn't need to be opened up to be slightly modified for other uses.