Update on the static electricity doodad

I was over at MHV last … Tuesday, I think. Looking for some help with building a static grass applicator for a mate.

In the end, I bought a small, battery-powered plasma globe. I wired a pair of oppositely-oriented 1kv diodes to the hot end, and put a high-voltage 470nF across them. I then added a pair of 1MΩ resistors and took leads with alligator clips off that.

And it seems to work.

Ideally, you’d want the signal from one of the diodes delayed 180° to more efficiently charge the capacitor. But doing that involves some science that I don’t have. Maybe just using a longer lead on one of the diodes would do the trick. In any case, that sucker is defnitely charging as-is.

I found something interesting inside the generator - an inverter chip. I’m betting that they actually use a minecraft redstone oscillator to generate the RF signal for the transformers: a loop of an odd number of inverters.

So, all’s well that ends well. I never got the other thing going, but I learned a thing or two trying.

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Blog post here.

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I’d like to see it. Can you bring it next Wednesday?

What’s the goal? Are you trying to do crop-circles ? :flushed:

My high-voltage project at the moment is getting a flyback transformer to drive a spark gap.

That’s a great project. I suspect the reason the circuit works is because the HF signal applied at the “input” is finding a ground at RF via the output probes. I suspect it’d be more efficient if you could find the internal ground inside the plasma ball circuitry and apply that along with the hot end as the two inputs into a full-wave bridge rectifier but at the end of the day, what you have works (and who knows, if you made it too efficient you might start exceeding the abs. max voltages on the parts you’ve used :).

FWIW 2kv across 2M ohms is about 1mA current, you probably don’t want to risk delivering much more than that into a human if you don’t need it. For comparison, I think earth leakage/RCDs found in homes in .au must trip at no more than 30mA (with hospital and other medical gear tripping much lower).

Edit: if this was a commercial product, you’d need a more robust current limiting device (resistors are subject to failure and breakdown votlages too).