Its probably not linear and not too useful but i think its ok for the amount of time i had to put into it. Its basically a mashup of two circuits that i have posted some time ago.
Edit: Alright i had it working 1 sec ago but when i restarted the sim it started to be spastic.
Edit 2: I added a cap at the inverting input of the bottom left opamp so the sim starts up but now it will start at -1kV and create some weird undershoot sometimes... At least one can see its working principle now.
First scroll out a lot and after the orange line crossed 0V scroll in to sth like 5ms to have a rather stable sim.
Edit 3: As @hurz suggested, I added a relay to the now 100mA CC supply.
