I recently recycled a couple of computers and salvaged the power supplies out of them. I spent the day converting an ATX computer power supply to a benchtop power supply. Should be handy to test avionics and numerous other devices that need a small amount of power. This idea was suggested in one of the SonexTalk posts. I browsed the web and found several sites with instructions. I used this site: http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply
Cost was about $10 for parts at Radio Shack.
This is a "regulated" power supply, so the voltage should be stable with various loads. The amperage rating varies with the voltage used. See image 2 for this 250 watt P/S.
Voltage output ranges from -5vdc to +17vdc with multiple voltages in between depending on how you pick off the leads. Basically you get the voltage difference between two terminals. Between gnd (0) and 12vdc is 12vdc. Between 12vdc and -5vdc is +17vdc, between +12vdc and +5vdc is +7vdc, etc. I didn't bring out -12vdc which would have given a range up to 24vdc. This was mainly due to space constraints for the binder posts.
I had to move the fan outside the case because the majority of the bulky wires normally leading out of the case are now internal.
