Just out of curiosity, what would happen if the main PSU (DUT) is cutting on/off? Is that still going to be safe since the 12v PSU for the controller will be losing power too?
I remember you saying something about finding a solution for a startup issue but will that still suffice in a situation of DUT dropouts?
If you could include some extra large caps on the 12v rail, that would allow the control circuit to remain running even with repeated short dropouts of the DUT. Provided that does not cause problems with your startup timings solution.
I think we are ok. The problem with power up was the 12 volts had been on but no 24, so the fet was turned on fully because there was no current. When the 24 came on the long time constant of the integrator kept the current very high for quite some time. Now the 12 comes on after the 24 so that problem is gone.
I have played with power down, but not since we said we would go up to 50 volts. There might be a problem there.
When it was just the 24 the maximum current was limited to 4 amps by the pot running off of +12. I have a diode from +12 to +24 to keep current from going backwards thru the regulator so the 12 volts follows the 24 down. It did look like there were some timings (power on/off glitches) that would get the current a little higher than the set point but not higher than 4 amps/FET.
Jeremy, I'm not sure the auto tune circuit is so complicated. But it is often not as simple as it seems. It may complicate this power up/down stuff, but it is more a matter of trying to plug all the possible holes.
Where would you go in Calif. San Fran probably? I lived up that way for a while in San Ramon. Also spent some time in So. Cal. Really liked it, but make sure you get some $. Most companies out there are ready to help with housing and stuff. Or they used to be.