My two cents is, if you want to de rust machine sized parts and not have it take three lifetimes you will need a much larger power supply than something sized for a computer. The amount of surface area exposed in the tank on the rusty part and the anode element used in the tank, along with the strength of the alkaline tank mixture will determine the strength of the current needed. With a improperly sized setup you could spend a month trying to clean one rusty automotive steel wheel clean enough for painting that will hold paint without rusting with the road rash they receive in use.
My tank made from a large industrial chemical tote, about 300 gallons uses a 12V 100A battery charger that was intended for a piece of industrial equipment to charge its onboard batteries. With a large tank, plenty of anode plates hung around the inside, the proper strength of the conduction solution and plenty of low volt DC power you can de rust a set of wheels in a couple of days with a small amount of hand cleaning and repositioning the parts in the tank so that all faces of the parts hang facing the anode plates for a period of time.
With a couple of amps from a computer power supply I would doubt that you could clean a set of wheels for quality painting in several months.
More power in a properly set up tank and solution means less time and work and much better end results. Not to mention the size of the parts you can do in a single batch. But small scale will work if you have no reasonable time limits.
. I have read literally dozens of how to's on the web relating to converting a psu to a bench top power supply - simple steps 1,2,3 and done. I have no idea why this one is so difficult.
