Re: Charging a capacitor to 6kV

On Apr 1, 5:27 am, birdburdy <birdbu...@xxxxxxxxxxx> wrote:
I would like to charge a very small (1nF - 500pF) capacitor to fairly
high voltage: 6kV (enough to get a reasonable spark). I believe the
easiest way to do this is using a Flyback Transformer, or a Blocking
Oscillator? I would like to use just two AA batteries for this.

I don't especially want to wind my own flyback transformers - is it
possible to use an ordinary audio transformer as a crude flyback, then
use a Villard cascade to get the voltage up?

Two possibilities: I have an "electronic fly swatter" from Harbor
Freight that cost all of about $3 on sale (and sometimes they're even
cheaper), that charges a somewhat higher capacitance to 4kV. It uses
a simple blocking oscillator, and it should be easy to voltage-
multiply that up to 6kV or higher. It runs on, as I recall, a couple
D cells. It would be really simple to remove the little board, add
multiplication as needed, and repackage into a small box.

Or, use the transformer out of an LCD display panel backlight.
Biggest problem with that is that it seems to usually be the
transformer that dies in those supplies, so finding a dead supply to
scrap a good transformer from may be frustrating.

You can indeed use an audio transformer to do the job, along with a
multiplier. Especially if you can find one designed for use between a
small vacuum tube and a speaker, the turns ratio could be reasonable.
I'd be cautious letting the secondary go beyond perhaps 500 volts
though--it's hard to know just how carefully the winding was done with
respect to high voltage insulation.

Cheers,
Tom
.

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