OK... Goofing around today on my bench with some power mosfets... found a bunch of "high voltage" capable IRF820s and IRF830s. Sorry about the rough sketching...
I have a variable bench supply that can deliver 100ma, from 25vdc to 500vdc.
100K plate and cathode resistors, same with drain and source... just swapped out the triode tube for a power mosfet.
B+ voltage divider at the grid of the vacuum tube triode and the mosfet gate are both around 3M and a grounded 1M.
# 1 and # 3 work "absolutely fine" with a few hundred milivolts of drive ,
#2 does not work at all... why?
I have a variable bench supply that can deliver 100ma, from 25vdc to 500vdc.
100K plate and cathode resistors, same with drain and source... just swapped out the triode tube for a power mosfet.
B+ voltage divider at the grid of the vacuum tube triode and the mosfet gate are both around 3M and a grounded 1M.
# 1 and # 3 work "absolutely fine" with a few hundred milivolts of drive ,
#2 does not work at all... why?
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