Power Supply

I recently extradited a power supply from an old computer with the intention of using it as a power supply for a project I"m working on. I realized though that I do not know how to turn it on. I plugged it in, but then I guess I would need to trigger some kind of short circuit right? Like when you push the power button of a computer, isn't that what's happening?

I think so. old PS were a bit different They were switched on when you short two specific points and turmed off when you open those points(a simple switch), The new ones are controlled electronically.


Which one is your power supply

Here it is!

If your power supply is a ATX type Then you should connect a RED wire and a BLACK wire to high power (5 or 10 W) 10 ohms resistor, and connect ORANGE wire which is 3.3 V to BROWN voltage sensing wire. You can’t use 3.3 V in this arrangement nor should you use same red and black wire you used to connect to resistor. You can now connect GRAY wire to 330 ohms resistor, LED and BLACK wire. Finally connect a GREEN wire and BLACK wire to DC off/on switch. When you hit the switch ON your PS should work. If you have different colored wires or missing some tell me so I can tell you what to do! Now you only have to use leftover wires to make some connectors or something like. BLACK wire is GROUND, YELLOW is +12 V, RED is +5 V, WHITEis -5, BLUE is -12 V. As about current I’ll tell you when you check if you have ATX or AT PS and if are colors ok.

P.S. You don’t need PURPLE wire, and GREEN and one BLACK can be shorted if you prefer to use rear on/off switch. This works mostly identical with AT PS but is aimed to ATX. Power load resistor tends to get hot so it should be mounted to some kinde of heatsink.