Floated HV Pulsar

[johnnypp]

I have a question about the high voltage pulsar that I have designed using Multisim. Just an aside, I also designed this circuit using LTSpice and it works without issues, just simulates very slowly. Okay, so, this circuit is exactly how I intended when the main power supply (V1) is set of 0 V. There are two outputs that are at a common potential when the input TTL pulse is low, however, when the TTL signal goes high the two outputs change to [common + 50V] and [common - 50V]. In reality, I will be floating the power supply and everything will be referenced to 8000V (8000V for this circuit will be ground for everything not including the function generator). When I increase the main power supply from 0 V to anything greater than 200 V, the outputs from the two MOSFETs are no longer pulsed. It appears at the evelated voltages, the first Optoisolator (U1) no longer functions as it should? Am I missing something here? Does Multisim's optoisolator's not function very well? Any suggestions would be greatly appreciated!

Thanks

Johnny

[lcgse88]

Hi Johnypp

Thank you por your post. I have one question, what should be the expected behavior? Do you think you can attach screenshot from LTSpice to see what we should see in Multisim. Thank you.

[johnnypp]

Hi icgse88,

If you run the multisim simulation with the main power supply at 0V. It gives the pulse train that I am looking for. I've attached a screen shot of the LTSpice simulation. Basically, this pulse training repeats every 40 ms. 

Thanks!

Johnny