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High voltage probe and high voltage resistors

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xzswq21:

--- Quote from: TimFox on August 01, 2021, 01:37:53 pm ---Of the three dielectrics you mentioned, "N4700" has a high temperature co-efficient (-4700 ppm/K), but its voltage dependence should be reasonable.  See others' comments about DC distribution across series capacitors:  you must use resistors to equalize the DC voltages.

--- End quote ---
Yes , I want to use two 500MegOhms or four 250MegOhms resistors.

Gyro:
It sounds as if you should build it out of a series - parallel combination of 500Meg resistors in that case. You don't have your country flag set, but Farnell have a 25% price break at 10pcs. I would think that other distributors would have something similar.


Edit: Sorry, I missed the "or".

TimFox:
The simplest approach is to make a series string of several resistors (more is better) and put equal appropriate capacitors across each one.  Again, resistors have a noticeable voltage co-efficient at high voltage, but ceramic capacitors can have huge voltage dependence—read the data sheet for individual types.  When last I worked with 100 kV, good high-voltage capacitors were easier to find (used in CRT supplies, etc.).

xzswq21:

--- Quote from: TimFox on August 01, 2021, 07:25:22 pm ---The simplest approach is to make a series string of several resistors (more is better) and put equal appropriate capacitors across each one.  Again, resistors have a noticeable voltage co-efficient at high voltage, but ceramic capacitors can have huge voltage dependence—read the data sheet for individual types.  When last I worked with 100 kV, good high-voltage capacitors were easier to find (used in CRT supplies, etc.).

--- End quote ---
I found several resistors as following:

MOX94021007FTE: (MOX940)



MOX96021007FTE: (MOX960)







SM108035006FE:





TimFox:
Choosing resistors with a specification (even “typ”) on VCR is a good idea.  Note that the spec is “ppm/V”, so the ppm (10-6) must be multiplied by the voltage across the resistor to get the fractional deviation (this can be derived from a quadratic function of current vs. voltage, rather than linear).

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