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Re: [TCML] Tuning, Capacitors, and Spark Gaps

Capacitors for microwave ovens were essentially voltage doubler caps, and
not really rated for RF duty.  With all those caps your internal losses
might be too high, and soaking up most of your input energy.

You might try substituting a friend's MMC type cap, or even a transmitting
mica type cap to see it that works.  That would be my first area of

Another good idea is to run all your data thru JAVATC -- free online.  It
will identify any design problems such as too few pri turns, etc.

Dr. Resonance

On Sat, Aug 22, 2009 at 3:19 PM, Joel Torgeson <joeltorgeson@xxxxxxxxx>wrote:

> Alright,
>     I've now built my tesla coil, and am very disappointed that it fails to
> work. My transformer is a 9,000v 30ma NST. I have tailor-built my capacitor
> out of capacitors from microwave ovens. They are internally resisted, and
> with 80 of them in series i hit my target capacitance of .0088 uf. My
> primary consists of 1/4 inch copper tubing spaced 1/4 inch between each
> winding. there are 15 turns of tubing in a flat pancake configuration. My
> secondary consists of approximately 760 feet of 24 AWG magnet wire wrapped
> around 3.26 inch outside diameter PVC pipe. The topload is of the tubing and
> pie-pan variety, using 3 inch aluminum tubing/ducting. This makes a ~ 15
> inch toroid on the top. i am using a 8 ft grounding rod that isn't attached
> to anything important. There is no metal inside the secondary, so that isn't
> a problem. My biggest concern is the spark gap. It's a static gap, not split
> up into multiple gaps, just one big one. it is 5.6mm wide, and has a
>  hair drier running on cool temp, high velocity blowing on it for
> quenching.
>     There's all the numbers i have, now i need some advice. I have been
> trying to tune it in for 2 days, and all i can get is the occasional 3/4
> inch spark (usually no more than 1/2 in for rapid sparks). It does light up
> a broken fluorescent bulb, and as i said, it makes some small sparks, but i
> didn't spend all that time and effort to create something my Van de Graaff
> can beat!
>     So, does anyone see anything obviously wrong? Any suggestions,
> comments, tips, or (yes) criticisms would be much appreciated.
>  Sincerely,
> Joel Torgeson
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