Riggin an ATX or AT Power Supply as a general power supply

[Rainsford]

I have some old power supplies lying around, and I'm also starting a project to do some lighting in my room with LEDs. I need a DC power supply for this, and I figured I might be able to use one of my old ATX or AT power supplies. Now I don't want to hook them up to a computer, so is there some way to rig them at act as general power supplies, or do they need a large load at all times and special feedback circuits or something?

Any help would be appreciated, thanks!

 

[phisrow]

An AT power supply can be used as a general supply just by turning it on(the external switch actually switches mains current). Depending on the age and quality of the said power supply, it might be a good idea to load it up decently before turning it on, and I wouldn't stash it next to your gasoline-soaked-rag collection in any event; but it should work just fine.
ATX supplies can be induced to turn on by shorting the appropriate rail to ground. On the 20 (or 24) pin motherboard plug there will be a single green wire. Short that to ground(any black wire) and you should be all set to go. Again, load probably isn't a bad idea; but I've run supplies before with very small loads and nothing has exploded or anything similarly exciting.
N.B. All my references to colour apply only to real AT or ATX standard PSUs. Some of the proprietary manufacturers have been known to do rather kinky things with their power supply pinouts, so be careful if you pulled the PSU from a Dell box or something.

 

[DrPizza]

Incidentally, how proprietary are Dell power supplies? My kids died and I have to replace it..

 

[Bassyhead]

Originally posted by: DrPizza
Incidentally, how proprietary are Dell power supplies? My kids died and I have to replace it..

there are adapters that allow standard power supplies to be used on dell motherboards with a proprietary power connector pinout.

 

[BigBadBiologist]

Originally posted by: DrPizza
Incidentally, how proprietary are Dell power supplies? My kids died and I have to replace it..

They pretty much have the same wires, just rearranged. I can't find the link now, but if you google dell power supply pinout, you should be able to find a diagram.

As far as using the power supply for a general supply, I did it with an old AT supply and it works fine. (I used it for part of the initial working of this contraption: http://mysite.verizon.net/vze85qtq/id15.html )

 

[TitanDiddly]

You're going to want to load the unused rail. If you're using the 12 and not the 5v, put four 25-ohm, 15 watt resistors across the leads. If you're using the 5v and not the 12v... you'd have to do the calculations, I don't know the specs for that one. Good luck! 😀

 

[Runamile]

Originally posted by: DrPizza
Incidentally, how proprietary are Dell power supplies? My kids died and I have to replace it..

How do you kids dying have anything to do with replacing a PSU?

Had to read it a few times to get what what going on.

And yes, Dell PSU are proprietary(as far as I've seen). The bastards make you go through them to get a new one. Now you might make you own, using google and a multimeter...

 

[KoolAidKid]

Originally posted by: DrPizza
Incidentally, how proprietary are Dell power supplies? My kids died and I have to replace it..

Sorry to hear about your children. 😉

 

[Calin]

A power supply will keep its rated voltages on the outputs only if there is a certain current flowing thru them. If there is not enough power absorbed, the voltage will grow to the maximum DC voltage that is generated by the source (and it can be quite a bit more than rated voltages).

Calin

 

[VirtualLarry]

I know that some people have repurposed old AT (and possibly ATX) PSUs , for use in old rebuilt arcade machines, you might check that out. Google for "MAME cab" or "JAMMA" and something to do with PSUs. You'll probably find many examples.

 

[mjia]

Dell motherboards can have a significantly different pin configuration for the power supply feed. Although they still use the same voltages, the number of pins for a particular voltage are not the same. Meaning, you can't just relocate the pins in a standard ATX PSU. You'd have to collect a few more feeds to certain pins. Some Dells also require an auxillary 6 pin connector (not the type used an servers).

There are adapters sold that will allow an ATX PSU to be used on most dells. I'm using one without any problems (purchased at endpcnoise.com). You could probably build them yourself, but I don't think the cost is worth it (was only $13).