I know there cheap, but on a radio forum I'm on the guys convert server power supply to run high current amplifiers. I know they hold up reasonably well, both up to 10 Amps with no external shunt, and up to 100 Amps with external shunt. I see what Ian is saying about not being viable to run off the supply its measuring. I probably will opt for a dedicated power supply, I should just be able to squeeze it in. I'm just curious if it would run off a separate regulator from the rectified and filtered input voltage. Its 15 Volts AC so around 21 Volts after rectification and filtering. I was going to try a 7812 off the filtered input. Diagram 2 does work, I wired it up to an atx power supply with a 50 watt halogen lamp. I'm thinking meter power wires to added 7812, yellow sense wire to main output. And current wires red black thick wires on negative side of the output. I've no idea what a capacitive rectifier is. Couple of what I'm messing about with. 5 Amp and 10 Amp units, in various stages of completion.