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Re: The OLTC`s gone pro.

Original poster: Finn Hammer <f-h@xxxx>

Tesla list wrote:

Original poster: "K. C. Herrick" <kchdlh@xxxxxxx>

That's beautiful work, Finn; I'm envious! Congratulations.


It's interesting about the breakouts: When I had my super-complex s.s. coil running, I found I didn't require a breakout at all (with the smooth 6" x 24" toroid). I got very nice 2 1/2 ft. sparks that danced all around the toroid. If you recall, I posted a photo of it with Terry. 2 1/2' ft. didn't satisfy me, I tried to improve it but made it worse & endlessly failing, & finally ran out of motivation...so it no longer runs.

I remember that coil very well, it was one of the coils that inspired me a lot. The videos from that warehouse on the harbour somewhere, was it not Ottalini who had those videos? were the first indication to me, that short bursts could make that "Bang" like lightning experience.

Do you need the breakouts, or are they just for the directing of the sparks?

Yes and no. It will break out from the smooth toroid, but:
Remember that this special coil is designed to simulate lightning, not to be a Tesla coil on display. The fact that it is a Tesla Coil is secondary to the experience to the spectator seing a small lightning. A Marx generator was on the agenda early in the design process, but fortunately, the attraction designers liked the branched streamers of the Tesla coil.

So instead of just running it flat out, to leave the impression of a lightning strike, it is run in short bursts.
The design criteria is that 1 kind of discharge is a forked streamer to air, 90% sure not to connect to the cage and become an arc.
The other kind of discharge is supposed to be 90%certain to connect to the cage and be seen as a white hot arc.

In this case, I have found that the streamer from a breakout point will develop into a 3`12" streamer with 12-15 bangs at 500 BPS. To be more than 90% sure the discharge grows into a connecting arc to the cage, being 4`away, 18-22 breaks are fired.

If I leave the breakout points idle, 1 1/2 feet streamers are produced with these short bursts.

Firing voltage is 900V, primary capacitance is 18µF, so the bang energy on the cap is 7.29 Joule. At 500 BPS, this would corespond to 3645W. Well sort of, because the primary caps are recharged from the resouar electrolytics faster than I can keep up, so the voltage droops during the discharge sequence.
Anyway, power is not an issue here, spark length is neither.
The break out points were just a freak idea I tossed out while negotiating the contract, and the time it took to develop them initially was well spent. It could need some refining, but it already seems to me like it is a necessity to have controll over where the sparks fly.

Cheers, Finn Hammer

Ken Herrick
Oakland, CA USA

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