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 7/12/01 9:06:46 PM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes:

> Original poster: "Peter Lawrence by way of Terry Fritz 
<twftesla-at-qwest-dot-net>" <
> Peter.Lawrence-at-Sun-dot-com>
>  
>  John Couture,
>               I've built half a dozen 3.5 x 12 inch TCs, all with different
>  wire diameters (500 to 2000 turns) and many primaries (5 to 25 turns),
>  and many Caps, and many Toroids, and many spark gaps.

Peter,

If the secondary is very small, such as only 12" tall, this tends
to limit the available spark length somewhat, although I've gotten
26" or longer sparks from such a coil at 120 bps.  Short coils
tend to breakdown as the sparks get longer with a larger bang
size.

>  
>  The best I've gotten is about 12" (maybe 14") streamers from a 9/30 NST. 
>  J Freau's calculation of 1.7 * sqrt(watts)  =>  28", so I'm off by a
>  factor of two.

A 9/30 nst with the 3.5" by 12" secondary should be able to give
longer sparks than 12" to 14".  The spark lengths should be able to
reach or approach 28".  BTW, my formula you mention above should
be used with the actual input power of the nst, not the rated power.
Some combos of input voltage, and cap size and bps, will cause
the nst to draw more than its rated power input.  For instance a
9/30 nst can draw 487 watts or more under certain conditions and 
should be able to give a 37" spark or so.
>  
>  As far as I can tell J Freau's formula only applies to 6x24" and larger 
> coils.

The formula should fit equally well for smaller coils of a synergistic
design.

>  
>  I'll admit that I still have to try blown and synchronous-rotary gaps 
though.

Some static gaps can approach the performance of a sync gap.  For
instance Gary Lau's vortex gap does very well.  But long sparks will
only be obtained with a synergistic arrangement.  

John Freau
--
> 
>  
>  And I'll have to admit that streamer length is not the same as "efficiency"
>  the way you are talking about it...
>  
>  YMMV,
>  
>  -Peter Lawrence.