# How to check the high voltage of a electrostatic device?

I want to build a device with two metal plates which needs to have 3000 VDC between them. The way that I am thinking is to use a ferrite transformer from a 9 VDC transformer with a transistor that switches a low DC voltage on the original secondary side to get 220 VAC on the original primary side. Like described here. But that is not the issue here.

By using a series of voltage doublers (in effect a voltage multiplicator) this voltage needs to be upped to 3000 VDC, like described here. Again, the voltage multiplicator is not the issue, but a way to check that high voltage is.

I would like to know of a way to check the output voltage of that circuit without costly and specialized apparatus.

• For some thoughts see this video. Mar 3 at 12:45
• Electrostatic VM? Mar 4 at 5:32
• How about a bog-standard voltage divider? Mar 4 at 11:16

The best way to measure the resulting DC voltage at the multiplier output is to get a HV probe for your multimeter, but good ones are relatively expensive, I think several hundred \$ for a Fluke one.

With care you could use a divider with a 100MΩ 1% HV resistor, a 10kΩ 1% and a DMM with 10MΩ input resistance to measure the voltage to within a few % for a couple dollars.

simulate this circuit – Schematic created using CircuitLab

A couple caveats:

• This will draw about 10x the current of the Fluke 80K-40 because the Fluke uses a 999MΩ resistor, so more loading of your source, which will reduce the measured voltage. Of course you could try to source a similar resistor or use 10x 100MΩ resistors but that's more complex. You also would have to know and adjust for DMM input resistance for the best accuracy.

• Don't be disappointed if your multipliers run out of steam at high multiplication ratios even without much loading. There's a practical maximum of around 10:1 if memory serves.

• I indeed made the mistake by writing 3000 VAC, I corrected this to 3000 VDC. Mar 3 at 13:54
• Deleted reference to AC. Mar 3 at 14:04