High voltage generator (20-30 kV)

Hi there. I just made a cool high voltage project and I wanted to share it with you.

I took a flyback transformer out of an old CRT television, an electrical ballast and two random plastic film capacitors. I made a little circuit that looks like this (click to enlarge):




The output is of about 20-30 kV at 15 kHz and 10 mA, but I didn't measure the exact voltage, so this is just an estimate.

Photos time! Click to enlarge
Some arcs:








Burning a piece of paper:








That's it! Feel free to post here if you have any suggestion/question.

P. S. The output of this circuit can be lethal under certain circumstances. Don't try to do that if you don't have any experience with high voltages and currents.

How did you select which primary tap to use?

Jaggions said:

50-60 mA, but I didn't know how to measure exact voltage and current,

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No, not 50-60mA. The arc would be bright white. Your setup is probably in the single digit milliamps, and is therefore not lethal.

Voltage can't be measured with standard equipment unless you rig up a voltage divider with 10s of resistors. Current on the other hand is easy and can be done with any ammeter. The ammeter does not pose a resistive load, so it will not be damaged by the voltage. Simply put your DMM across the secondary to measure short-circuit current (Be sure to have DMM in mA or A mode!). Do not perform this measurement for more than a few seconds though, since the secondary heats up.

Cyparagon said:

No, not 50-60mA. The arc would be bright white. Your setup is probably in the single digit milliamps, and is therefore not lethal.

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I'm not sure about that, back in my physics labs we were all told that it only takes 8mA to stop the heart. I know using low power sources it's unlikely the 8mA will make it to the heart, but with what jaggions is playing with I wouldn't go as for to say "therefore non-lethal"

Cyparagon said:

How did you select which primary tap to use?

Click to expand...

I found the primary by checking the resistance between the pins of the transformer. The correct pins are usually the ones with a 1 ohm resistance between them.

Cyparagon said:

No, not 50-60mA. The arc would be bright white. Your setup is probably in the single digit milliamps, and is therefore not lethal.

Current on the other hand is easy and can be done with any ammeter. The ammeter does not pose a resistive load, so it will not be damaged by the voltage. Simply put your DMM across the secondary to measure short-circuit current (Be sure to have DMM in mA or A mode!). Do not perform this measurement for more than a few seconds though, since the secondary heats up.

Click to expand...

You are right. I measured the current this way and it is about 10 mA.

TheDukeAnumber1 said:

I not sure about that, back in my physics labs we were all told that it only takes 8mA to stop the heart. I know using low power sources it's unlikely the 8mA will make it to the heart, but with what jaggions is playing with I wouldn't go as for to say "therefore non-lethal"

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10 mA should not be lethal (unless you have a pacemaker or some sort of heart disease), but it's still very painful. I wouldn't try that on myself.

EDIT: Very high frequency electric current can also cause tissue burning, even if it does not penetrate the body far enough to cause cardiac arrest.

Nice : )

TheDukeAnumber1 said:

we were all told that it only takes 8mA to stop the heart.

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Yeah, if you've got leads attached directly to the heart maybe. 30mA is generally the low-end of what's considered lethal, and that's in sensitive individuals

You wouldn't want to zap yourself with a flyback, just as you wouldn't want to shoot yourself with a BB gun. Sure, you can argue a BB gun could kill someone, but that doesn't mean a BB gun is considered lethal.

I've heard that tv technicians who get zapped are more badly injured due to their hands being flung into the sharp edges inside the enclosure

ilovegm said:

I've heard that tv technicians who get zapped are more badly injured due to their hands being flung into the sharp edges inside the enclosure

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Having been on the wrong end of an Anode cap countless times back in the 90's during my time as a TV technician, I can confirm this to be 100% true.

The zap you get is more of a burn, unless you get between the isolated/non isolated side of the chassis at the same time, that'll ruin your day every time.

I accidentally got across 2500 VDC capable of 500ma once, that was enough for me.