Re: Character Revisited

To: Tesla List <tesla-at-poodle.pupman-dot-com>
Subject: Re: Character Revisited
From: Alan Sharp <100624.504-at-CompuServe.COM>
Date: 26 Nov 96 07:01:41 EST
Richard Waynes post caught my eye - 
> Take heart Alan Sharpe.
I'm in good heart - I have a reasonable expectation that with
solid state coils I can probably make as much spark as my
work space can cope with.

>  I had ment to make clear, that if you could drive a TC with a      
>  class A solid state, or vacume tube driver, and a signal with the  
>  same frequancy components as a spark gap, you would see the same   
>  arc lenghts per primary power levels as you would get with a gap.

class D solid state is what we actually use. I would not argue with this
but the bummer is that when it comes to switching 10kV at 100A then
our swanking new hi-tech can't cope - and a simple peice of 19th
centuary tech - the spark gap will take it easily. (A lot of me finds
that very pleasing).

>    I think it's not the gap, but the frequancy content that makes     
>     gaps appear to deliver longer secondary arcs for a given power     
>     level.  Unless the frequancy components of the primary current are 
>     the same for the tube or transistor driver, we cannot make diurect 
>     comparisons to gap driven coils.

I think that the major difference between a solid state magnifier and
a spark gap is that the solid state (and the tube coil) applies the energy 
continuosly whereas the spark gap hits the coil with all the energy over 
a much shorter time period. Thus the spark gap will deliver a much higher
peak voltage - hence arc length.
You could make a bell resonate and sound by putting a loudspeaker
against it and applying the right note - it will sound but give the same
energy to a primitive hammer and you know which will give you more
ding for your dong.

But the solid state may be more efficent - shorter but much brighter
arcs. 

I am not sure about your results on frequency content. How did you
drive your coil - if you used an output transformer then of course
that has leakage induction and parasitic capacitance - masking
the frequency response of the coil. 

If you were driving the coil directly then your result is much more
interesting - I had assumed that only the fundemental component
was significant - the other harmonics in the square wave would
be wasted energy creating useless peaks at different lengths up
the coil. 

I'll be away for the rest of the week - conference in Scotland.

Alan Sharp