Is there such a thing as an opto mosfet?
I was just thinking about gain feedback that's DC isolated - is there SATAAOM? ;-)
In my mental imagination's movie screen, I see something like the old incandescent/CDS gain controls. HP used just the filament, but that was to stabilize the gain - essentially, I want to amplitude modulate a resonant oscillator.
Long-tailed pair in push-pull with a variable current source?