Using a computer power supply as bench supply

I've got a power supply out of an old computer I think it's an AT not an ATX style but I'm not 100% positive. I'm not really sure if there is any dead give aways here.

If it is an AT I'm wondering if I need to hook up a "dummy load" to operate it. I've been told when using an ATX it always needs to see some load to operate.

Thanks.

Rationalphi,

If the motherboard connector has only six pins, then you have AT, otherwise you probably have ATX. All you need to do is connect the PS_ON pin to ground and the power supply will work. For more info go here: ATX power supply connector pinout and signals @ pinouts.ru

DavidBear

Okay, looks like I've got an AT then. It is out of a quite old computer.
There is no grey or green wires either.

So I don't need to do anything else to this power supply?

I was intending to use this to provide power to a micro-contoller and some transducers all 5 volts and I was going to use the 12 volt outputs to power the coils of some mechanical relays.

I've heard these power supplies create a lot of noise. Do you think it will be a problem in this circuit? If so what might be the best filtering methods.

Thanks again.