| General > General Technical Chat |
| High voltage probe and high voltage resistors |
| << < (5/7) > >> |
| 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). |
| Navigation |
| Message Index |
| Next page |
| Previous page |