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

[Bert Hickman]

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...  :^)

Bert
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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.
> 
> Steve
> 
> 
> www.stephenhobley.com 317 201 4281
> 
> The Laser Harp Project - www.stephenhobley.com/build
> 
> ________________________________
> 
> From: tesla-bounces at pupman.com 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
>> one.
>> 
>> 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... :-)
>> 
>> Steve
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> 
> 
> 
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