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Re: My Coil: Problems?



---------- Forwarded message ----------
Date: Wed, 1 Oct 1997 07:58:01 +1200
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
To: tesla-at-pupman-dot-com
Subject: Re: My Coil: Problems? 

Hi Tom,
        There is a problem I've noticed when trying to run caps 
considerably smaller than the size required to match the supply at 
Fmains....

> From: Esondrmn-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Re: My Coil: Problems?
> 
> In a message dated 97-09-28 10:13:49 EDT, you write:
> 
> << 
>  Hey, I am back. I was away for a while but now I'm back at coiling.
> <SNIP>
>  concentrate all of the coil's output (torroided) on a breakout
> point. Now I
> get
>  sparks all around the torroid and the breakout point. When I remove the
>  breakout point I see a lot of discharge from higher secondary windings to
> lower
>  ones.
>  
>  I'd appreciate any input on these.
>  
>  Thanx
>  
>  Tom Heiber
>   >>
> Tom,
> 
> You now have 120 ma of current available (theoretically) and perhaps your
> spark gap isn't quenching as well at this higher power level.  When I used to
> run neon transformers on my 6" coil, I used a cylindrical spark gap with 6
> total gaps of about .028" each and it worked well.  If you have sparks or
> arcing on the seconday, you either are way out of tune or your coupling is
> too tight.  Find the best tune and if you still have the problem, try raising
> up the secondary (up away from the primary) about 1.0" at a time until the
> problem goes away.

You can get into the situation where the gap needs considerable 
forcible quenching to put the transformer fire out. Unfortunately, 
some kind of airblast may be the only way to do this and you can take 
that to the point where you increase the primary losses pretty badly.
Even relying on a rotary to quench can be a problem. Anything that 
causes the primary spark to stretch is bad news from this angle. As 
was noted in "High Power Electronics", switches like to close much 
more than they do to open :( More series gaps with the same overall
setting might be needed.

Malcolm