Variable Input to OpAmp outputs voltage to MOSFET pair

[johnnypp]

Can someone with more EE experience with me help me understand exactly how this circuit works. It takes two +- 500 V rail supplies and varies the output using an analog signal from 1-10V into an opamp. I don't see how the opamp is controlling the output but clearly it is. 

[Rscd27]

Can you let us know from where do you get the circuit and what is supposed to do? I will suggest that you place pictures of your analysis too.

[johnnypp]

Hi,

Well, I reverse engineered this circuit from a PCB that isn't working currently. Basically, that PCB as two channels where each channel is the circuut in the simulation file that I posted several days ago. This PCB has a +/- 500V supply rails that are used to output the correct voltage. An analog input signal varying from 0-10 volts corresponds to an output of 0-100V. The company that made this PCB is out of business and I am trying to figure out exactly how they got this PCB to work. I believe they are using the FETs as a variable resistor to output the appropriate voltage. I've attached a few charts to review. The current output from the Optoisolator decreases with increasing analog input (0-10 V).

Thanks

[Rscd27]

Hello,

I have to be honest, I do not understant the circuit or how it works. However if you have questions with the Multisim enviorment or how to configure it to do a certain operation I can help you out then. I believe only an Electronic Engineer can help you out at this point.

Regards