- Joined
- May 27, 2016
- Messages
- 3,479
You do exactly what I do for monitoring high voltages. I made a divider chain for displaying the kV from a adjustable 4kV 200mA power supply for a Varian transmitter tube, but at the low end, I included metering shunt extras as safety circuits in case the bottom end inadvertently went open. Also, after getting into a job using Cockroft-Walton multi-stage multipliers, I salvaged the project leftover high voltage capacitors from 20pF to about 500pF, before they were collected up for disposal in a "tidy-up". Honestly, they have not moved in years, and might be called clutter, but occasionally see use, like now with things like scintillator PMT setups.
I know you will have had a brief mental estimation on putting caps in series, so halving the capacitance while simultaneously doubling the voltage, which still remains unhelpful if the capacitors have available have values too high. In practice, it works OK, but they need high value resistors across them to share out the voltage equally. If the resistors have high enough ohms to not waste energy getting hot, then the whole thing takes ages to discharge.
For me, when you proposed using a X-ray sensitive photodiode instead of an electron tube, it brought a smile, and I readily went for it, even though it was in the face of a completely proven high voltage alternative!
I know you will have had a brief mental estimation on putting caps in series, so halving the capacitance while simultaneously doubling the voltage, which still remains unhelpful if the capacitors have available have values too high. In practice, it works OK, but they need high value resistors across them to share out the voltage equally. If the resistors have high enough ohms to not waste energy getting hot, then the whole thing takes ages to discharge.
For me, when you proposed using a X-ray sensitive photodiode instead of an electron tube, it brought a smile, and I readily went for it, even though it was in the face of a completely proven high voltage alternative!