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Re: Coil Design for Review
At 11:32 AM 10/26/1999 -0600, Tesla List wrote:
>Original Poster: pmathus-at-learningco-dot-com
<...>
> transformer: 2 banked 12kv 30ma NSTs, for 12kv 60ma total.
>
> sparkgap: static RQ/TCBOR type gap, fan cooled, 13 gaps of .03 each for
> total gap of .39"
>
> tank capacitor: Fair Radio .01 mfd 100kvdc cap
>
> primary: flat, 15 turns of 1/4" refrigerator tubing at 1/4" spacing,
> inside diameter 8", outside diameter 22.5", 60ft total. inductance
> 92.9 uh
> secondary: 6" x 24", 22 gauge magnet wire, 37 turns/inch. approx 900
> turns. resonant freq 304 kHz unloaded, 154 kHz loaded with toroid
> below.
>
> Toroid: 30" x 6" aluminum ducting, C(pf)=32
This is almost identical to the specs for my 6" coil. I would add one more
primary turn for a total of 16 for this large of a toroid. I use two
toroids, one
4" x 18" corrugated aluminum for the bottom, and a 6" x 22" , also corrugated
aluminum, just stacked on top of the smaller one. It tunes at turn 15
with 48" streamers on average. I have another toroid I use at 6" x 28"
which requires tuning point at turn 16. I get 53" out of that one.
I built a 3rd static gap that is a hair more narrow than yours in gap width,
using 1" diameter copper pipe for the electrodes and it works well. With this
many gaps it might be a good idea to test out the gap unit on just the NST
first to make sure your firing voltage is set properly, and that all the
gaps will
fire on just the NST. If they don't, you will have to adjust them to closer
to .025
(width of a hacksaw blade). Also, make sure you adjust out your safety gap
or it will fire like a machine gun the first time you light up the coil.
I also use the Fair Radio .01 mfd cap. It's built like a tank and works
extremely
well.
Don
http://www.fwpd-dot-net/dona/tesla/teslacoil.htm