Re: Am I missing something here?...

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

Original poster: FutureT-at-aol-dot-com 

In a message dated 11/2/03 2:54:16 PM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:

>Alright, I've setup the coil as described and even though I've confirmed
>through an oscilloscope that it's resonating, I still get nothing even
>beginning to approach the claims that it will shoot 17 inch sparks.


Hello,

Has someone built your particular coil design exactly as you built it
and found that it produces 17" sparks?  What are the 17" spark length
claims based upon?

My formula does indicate a 17" spark for that NST power input, based
on a near-optimal design, but many things can hurt the performance
such as;

1)  Lower voltage NST's generally don't do quite as well as higher
voltage NST's.

2)  Spark gaps are often a weak point.  My work is mostly based on
syncronous rotary spark gaps and triggered sync spark gaps.
Sometimes simply setting up a fan to blow on the static spark
gap can double the spark output.

3)  A good properly sized topload is essential for good results.

4)  Secondaries having 1200 to 1500 turns may out-perform in
many cases.

5) Primaries having a greater number of turns such as 15 turns or
more may outperform.  Of course the secondary and capacitor
value must be such that the whole thing tunes correctly

6) A somewhat LTR valued capacitor is helpful.  I didn't calc your
needed LTR cap value.

7) Low powered coils (under 300 watts), have trouble meeting the
formula's expectations, and spark lengths may be about 10%
shorter than expected

John


>I've the the 5000/20 NST attached to two 2nF/40Kv doorknob caps in parallel,
>for a total of 4nF. From there, I have a single static spark gap which is two
>.5 inch copper pipe elbows which are basically impaled on screws and
>rotatable, and the primary coil which is 4 turns of .25 inch copper tube,
>with turns averaging 1 to 2 inches apart (It's a little messy right now, just
>sitting on the floor bare) which tunes when tapped around 2.5 or 3.5 if I add
>the third doorknob cap (Whew - I'd get marked down for a runon if this were a
>test).
>