Re: flat coil ?

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Chris, 

Tesla list wrote: 
>
> Original poster: "Chris Swinson by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <exxos-at-cps-games.co.uk> 
>
> Hi Bart,Paul, all, 
>
> I did some calcs on tube wound coils and it looks like inductance is more 
> with a flat coil?




In the realm of practical hd ratios used, yes. A solenoid can get close to the
flat inductance value if you just wanted to see what geometry caused highest
inductance on a solenoid, but it probably won't be practical to build or even
run as a classic coil. 

>
> capacitance looks about the same to the results below.




I think sess on a solenoid. On say a normal hd of 5:1 (10x50.7) solenoid for
your wire at 2000ft, Cself is around 21pF. At an hd of 3:1 Cself is still 21pF.
Even at an hd of 1:1 Cself is only 26pF. Now if you went in the other direction
outside of the norm, Cself would climb quite high, but it would only be
academic. 

>
> Frequency is about 220khz with tube wound coil.  Would I expect the flat 
> coil to work better than a tube wound coil ?




You have to be more specific by what you mean here by "works better"? For long
sparks? then no. (at least not in a simple flat configuration. Too many
physical limitations). 

Take care, 
Bart