The simplest is get a older PC supply like the pentium 100-200mhz board supplies. Anyway the older PC supplies dont require a load to make them run all you have to do is yank all the wires but the yellow and black there will be maybe 4 or 5 of each cut out the rest red is 5V if you want to add that. but run a couple of the wires to one banana plug to help with carrying current. I have 2 sets of 12V on mine and a cute little Radio shack panel meter I have been using this supply for 3 years now. Got more use out of it than I did the PC.