Re: "I want bigger sparks!" (me too)

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

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

> but the
>  maximum spark length is about 12" for any of these combinations.
>  
>  If anyone else does better on a coil that is only 12" high I'ld like to 
know
>  how also!!!

Peter, all,

In some of my tests, I obtained at least 28" from a 3" x 12" 
secondary.  THe sparks may have been longer, I'd have to 
check my notes.  More below.
>  
>  
>  I've seen my sparks go from ~6" on 6-30 NST, 8~9" on 7.5-30 NST, to 10~12"
>  on 9-30 NST, so I expect the trend to continue, but perhaps as your 
> experience shows it might level off instead. 

The trend should continue.

> since I burned out my 7.5-30 NST I ALWAYS use a safety gap, and my 
> spark
>  length measurments are based on having a safety gap set appropriately for 
> the NST voltage).

There is controversy regarding what the appropriate safety gap
setting is.  I like to use a safety gap setting that is a little wider than
what the NST can jump by itself.  For example, on a 12/30 NST,
I use a 1/4" safety gap on each side of the NST for 1/2" total.
This may reduce the reliability of the NST, but I haven't seen
any evidence of that.

I suggest that everyone who has questions about their spark
lengths from NST powered coils should state their safety gap
spacing in their postings, so the readers can take this into
account when analyzing the coil.  The design of the safety
gap should also be described because this will affect the
breakdown voltage.  A ball type gap will have a higher 
breakdown voltage than a wire type safety gap.  The diameter
or radius of the ball should be stated.  I use 10awg wire for
my safety gaps, and I let the sparks arc off the side of a
curved section of the wire to the NST case.

John Freau  

>  
>  -Peter Lawrence.