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Re: Newbie Design help



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

In a message dated 9/18/01 7:17:31 PM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes:

> Input: 15kv, 30ma NST.
>  Will this be long enough? Is the thickness opitmal? Is the spacing 
adequate 
> to
>  prevent arcing between turns? I've read that an inverted cone shape 
> increases coupling, so is it worth it?

Patrick

In my opinion, the inverted cone shape gives no benefit, I'd make
the primary flat.  You (or someone) will have to calc or use a computer
program to see if you'll have enough turns in the primary the way
you plan to build it.  1/4" is plenty think enough, and the spacing
is plenty.  I used 10awg close wound wire on my TT-42 TC which
can be seen at:

   http://hometown.aol-dot-com/futuret/page3.html  

There's a link at my site to John Morawa's TC (URL) which uses a 
15/30 nst and a 1/4" copper tubing primary.

It is of course much easier to adjust the tap point using copper
tubing than using any type of insulated wire.  I used insulated wire
to keep the coil compact.
>   
>  Secondary: 4.5" diameter, 24" long winding of #24-guage magnet wire
>   
>  Again, would this be the "optimal" design?

It will work.  I and others have found the best results using a thinner gauge 
secondary wire, but some others disagree.  In any case it must be
remembered that most of the optimal-ness is created by the
value, design, and quality of the spark gap and the capacitor....
not by the design of the coil it self.... which is more tolerant
of variations. 
>   
>  Caps: Saltwater caps - need some help here - how many?

Quite a few for best results.  There're somewhat lossy, but they
work and are cheap.

>  Toroid: Again, no idea. Need some input here.

I use a 4" x 13" smooth toroid on the TT-42 TC, but a 4" x 17",
or a 5" x 20" dryer duct toroid give the same spark length of 42".
>   
>  So how does all this sound? Obviously, I want to optimize my design for the
>  given NST. I'd like it to be upgradable too, as I have lots of NSTs I 
could 
> run together.

Since you want the coil to be upgradable, then it must be built
large.  I would make the secondary 6" x 30" or so, then you can
raise the input power and get 70" sparks or so with adequate
power, even more if you raise the power even more, and run
it at a higher breakrate.

Good luck,
John

>   
>  Thanks a lot!
>  Patrick