Dell PS Conversion

From Fozzee.net

I've wanted a "bench" power supply for testing and development for some time, but I've never come across quite the right thing. Cleaning some stuff up in the garage, I came across this Dell Tiny-ATX power supply, and figured it fit the bill. I snipped all the leads, added a power switch (to ground the ATX-ON pin) and connected the ground, +5v and +12v lines to some banana plugs salvaged off an old breadboard.

I flipped the switch and the fan came on. I put the slightest bit of load on the +12v rail, and the supply stopped cold. After a quick power cycle, it came on again. Loaded again, same effect. The +5v rail seemed to work fine, though. A bit of help from google revealed that most ATX power supplies won't run at all without a bit of load on the +5 rail. I added an external load to the +5v and then loaded up the +12v, and it worked great. You can see where I've zip-tied a sandblock resistor to the inside of the case, using masking tape to prevent any shorts.

In retrospect, the +12v output of this supply is pretty whimpy at like 7 or 10 amps... If I had to do it again, I'd go find some giant old AT supply with a 20 or 30 amp +12.