Re: A 1/4 wave Tesla coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <ajones18-at-bellsouth-dot-net>

>Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
><FutureT-at-aol-dot-com>

>system, but maybe not.  In any case, I would think that for longest
>sparks, you would want a toroid size that gives just one breakout or
>maybe two, even without a bump.  If you're getting a lot of sparks
>all around the toroid without a bump, then the toroid may be too
>small.  Low breakrate (120 bps), seems to need larger toroids in
>general.  Sometimes for longest sparks, the toroid has to be almost
>1/2 the expected spark length. I mean for a 105" spark, a 45" toroid
>may be needed at 120 bps, but a 36" or 40" toroid may be OK.  Also, I
>like the minor toroid diameter to be about 1/10th the spark length. 
>so for a 105" spark, the toroid would be about 10"  to 12" thick. 
>Such a large toroid may increase the spark length about 20% or so? 

I agree with John on this. I use the biggest toroid I can that will
still breakout. Every time I have increased toroid size the spark
length has also increased. Never had one that was too big, just too
heavy.

>Of course there's a range of sizes that will work well.   BTW, Alan
>Jones has done excellent work with large toroids on his coil, and has
>gotten something like 100" sparks from two of those photocopier type
>transformers.  I've never heard of anyone else getting these kinds of
>results.  I think Alan is using 1300 turns on his coil.  Alan is also
>running his coil at 120 bps synchronous.  

I wouldn't call it excellent, but do appreciate the compliments. It's
a large toroid, 9-1/2"x49" and so heavy I can barely get it on top of
the coil. I had to build some shorter supports for the two coils so
that I could get it up there. And it's too small and wants to breakout
in too many places. Even with strips of metal taped to the side it
will still breakout in three or four spots. This can be seen on my
webpage shown in the sig below. I have a large innertube that I may
try someday if I ever run this coil again. Build the biggest toroid
that space will allow and that can be handled is my opinion on this
subject. Of course it has to breakout too. 

Alan
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