Re: TC efficiency, was Math help...

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

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

In a message dated 7/15/01 1:47:42 PM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes:

> Original poster: "John H. Couture by way of Terry Fritz 
<twftesla-at-qwest-dot-net>" 
> <couturejh-at-worldnet.att-dot-net>
>  
>  
>  John F -
>  
>  A well known characteristic of Tesla coils is that the watts per foot of
>  spark increases as the TC gets larger. This means losses increase and
>  efficiency decreases as the TC is made larger. The range is about 200 watts
>  per foot of spark for small coils to 2000 watts for large coils. This is
>  based on measurements that  coilers make every day. Have you made
>  measurements that would indicate the contrary?
>  
>  John Couture

John C,

I agree that the sparks per foot of spark increases as the TC gets
larger, This is seen very clearly from my equation:

   spark length inches = 1.7*sqrt input watts (wallplug)

However I do not consider this to be evidence of a decreasing
efficiency for large coils, and it has nothing to to with increased
losses.  Rather I think it suggests that it's
"natural" for coil output to follow this square law, simply
because one is ionizing a large spherical volume of air
around the coil, and also because the sparks get 
not only longer, but a lot thicker in a large coil.  To measure
the true efficiency of a coil, other methods (other than 
spark length per unit of input power), must be used.

John Freau