[clab]

I'm an experienced EE and this looks like a good design to me. If you use a mig welder as a power source, you'll need to add some major capacitors across it to reduce ripple (without them it might be 100%), and check polarity first! Mine can be set up either way, and reverse polarity will fry this circuit instantly. I'd suggest using a fuse of some sort in series with the Mig welder, but after the capacitor connection (so the charging current of the caps doesn't blow the fuse when you turn on the Mig), quick blow. The old rule of thumb is about 1000uF per amp needed, but you can go up from there if you want it really nice. The bigger the difference between input and output voltages, the more heat the fets will have to dissipate for a given current. Use LARGE heatsinks, and keep an eye on the temperature. Here I have a supply about equivalent to a Mig, but on a variac, so I can keep the in out differential voltage close by an occasional manual adjustment.

This design could easily be adapted for lower current used in (non chrome) plating, and ought to work well for that too. For that I would use larger source resistors for the fets and a more dc accuate opamp. It *might* work ok as is if you simply increased the series R from the voltage reference, but that would make it really drift sensitive.