Ooops, somehow, I lost the last two "OR's" when copying this scheme into email.
Yahoo has a mind of its own at times.
Here's the whole idea(s):
If you want to measure the voltage at the filament on those follower triodes
may I suggest the following scheme:
Use an AD536 to convert to RMS right at the tube.
Use a LM331 to convert the voltage to frequency.
Send the frequency out over an optical fiber and read it with a frequency
counter or alternately convert it back to voltage with a F-V converter.
Power it with a tiny hi voltage isolation transformer. Only requires milliamps
Or use a power over fiber cable scheme, though those are rather pricey.
Or rectify and regulate the filament voltage to power the interface.
Or eschew the RMS chip, add an absolute value circuit in front of the V-F
converter, and then process the resulting signal down fiber. A small
microprocessor should be sufficient in lieu of that pricey RMS part. There
might be a touch of error down at the lowest transmitted frequency, though it
should be less than .1%.
Just the complete thought,
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