I needed a voltmeter for HV to be able to be seen from a distance at night. Here is my digital voltmeter with HV probe reading 13.06 kV. “Continue reading” for more details and photos.

Digital voltmeter 30 kV DC

I specifically need this for my big pulse capacitor bank which I wanted to run at higher powers. The capacitor bank is rated to 12 kV so the meter needed to cover at least that and also be isolated so running off rechargeable battery power.

Above shows the meter reading 13.06 kV using a 30 kV rated HV probe. The leads and switch are at the back. There is some rudimentary HV protection using a neon pilot globe, capacitor and a small toroidal coil in the main lead.

Analogue Voltmeter 60 kV

My main voltmeter is an analogue one made from parts on hand. Using the meter from my old x-ray unit (with a dial reading of 100 kV full scale deflection – FSD for 125 uA), I added a resistor chain (720 M Ohm, 72 M Ohm, 7.2 M Ohm, 800 k Ohm) to allow FSD of 100 kV, 10 kV or 1 kV. The current is full wave rectified at about 100 V level with fast diodes (BYV-29 500 Volt, 9 A, 60 ns) and is protected by a gas arrester and diodes across the meter itself. A bridge rectifier gives the ability to read DC and mean AC. Voltages up to 1000 V agree with my digital voltmeter to within around 5 % on DC and mean AC 50 Hz. A 30 kV DC power supply seems to read accurately. This is not intended for Tesla type frequencies but it is reasonably non inductive and the diodes are high speed ones. A capacitor divider is needed as well for higher frequencies. All the main workings are behind the acrylic to avoid accidents. Although the resistors have a peak rating of around 100 kV, the spacing between strings is not enough for more than 80 kV before big sparks start jumping everywhere although without damage to the meter.

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Photo Date:  March 1st, 2008, 2004