/diy/ - Do It Yourself

>>1430853
If you're extracting the signal from the high-side then you need an isolation capacitor, but form low-side you don't. I don't have such a cap lying about so my one will probably be low-side. I think you get a higher signal:noise ratio with high-side signal extraction, at least if you have a larger resistor on the high-side than the low-side of the tube.

I don't suppose there's anything wrong with pic related, since it has a 10M resistor? Though I'm unsure what kind of signal I'd get, I think a small spike?