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Re: realistic expectations from mini coil ??



Original poster: Bart Anderson <classi6-at-classictesla-dot-com> 

Hi Jon,

I didn't get a chance until recently to take a look at your numbers (have 
been making many updates to Javatc lately). It looks like it should tune in 
at 5.25 turns, but would probably do better at 5.5 turns which adds about 
6% inductance for a little bit of offset tuning. But the question was 
expected sparklength. You mentioned TelsaMap showed a max of 19". Javatc 
also showed 19" in the Static Gap section. Sparklength in the Transformer 
section showed 15.8" (based on power and coil diameter) and may be more 
realistic. In any event, you should be able to do better than 5" and 
probably just need to work on tuning and coupling to get there.

Take care,
Bart

Tesla list wrote:

>Original poster: "Jon Lagler" <rockcrawl-at-enter-dot-net>
>I've just finished a new mini coil and was wondering I should expect for 
>maximum spark length. Primary is a flat spiral, 10 turns of #8 solid round 
>copper, 2.5" id, 9.5" od.. Secondary is ~1458 turns of .006" wire, machine 
>wound on a 1.75" dia cardboard (paper towel tube), 8.75" winding height, 
>saturated and coated with Techspray Fine-L-Kote HT. Transformer is a 4000v 
>30mA NST. Capacitor is five 2kV .15uf CDE 942c's in series for 30 nf. 
>Spark gap is a single static gap using two tungsten electrodes spaced as 
>far as possible. Top load is 1.5"x4" tin foil covered toroid, will be 
>upgraded to a 2"x6" spun toroid. TeslaMap calculates a theoretical maximum 
>spark length of 19.1 inches. Assuming my coil is not nearly perfect I was 
>hoping to get at least 10 inches or so. So far I have been able to get 5 
>inches to a grounded object . What can I realisticly expect from this 
>thing? Any suggestions are welcome as far as how to improve the 
>performance. I suspect the larger, smoother toroid will help, but I don't 
>have it yet.
>
>Jon
>
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