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Re: [TCML] Strike rail hits and loud bangs - streamer shorting primary to strike rail?

Hi Steve,

You may be getting periodic flashovers between the outermost primary turn and the strike rail. The remaining outer turns (turns outward from the primary tap) will add to your normal primary tank circuit voltage through transformer action. When you moved the strike rail lower, it helped to fix one problem but may have introduced another.

Try increasing the height of the strike rail a bit. Or, better yet, remove the strike rail. As long as you have a safety gap with a center ground connection that's tied to RF ground, streamer hits to the primary will be harmless. As you've seen, a strike rail can often create more problems than it solves... :^)

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Stephen J. Hobley wrote:
Yes I moved the tap point out one coil turn - so that would have
higher L (I think).

So could the bang/flash be a streamer connecting the primary and the
strike rail together - thus dumping the tank cap out to ground?

It only happens on the part of the strike rail that has the ground
connection attached to it. Freezing the video shows that the light
flash is coming from the back of the coil, at strike rail level.


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From: tesla-bounces@xxxxxxxxxx on behalf of bartb Sent: Wed 10/1/2008
10:15 PM To: Tesla Coil Mailing List Subject: Re: [TCML] Strike rail
hits and loud bangs

Let me guess Steve, the tap point had a little more L (slightly
higher inductance). Am I right?

Also, yes you can tune a coil into self destruction. Tune it to where
it's "barely" in tune and with slightly high coupling. This will compound into a myriad of racing sparks and sure self destruction is possible (a shorted secondary turn or similar issue). Been there and done that. You can even over power a coil and turn it into a flaming puff of smoke (I haven't done that yet [knock on wood]).

Take care, Bart

Stephen J. Hobley wrote:
We have a fairly simple coil using a 60ma NST. Recently I changed
the tap point on the primary and by chance hit a really sweet spot.

Usually the Tesla Tuner is pretty accurate and gives good results,
but in this case it did not indicate that this tap point was a good

The streamer length has increased by at least 50% - but we did
notice some rather worrying "bangs" from the Terry filter spark gap
when the strike rail is being hit. Is this normal?

Is it possible to tune a Tesla coil into a self-destructive state?

I would take some pictures, but the darned thing scares me to
death... :-)

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