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

[DC Cox <resonance@xxxxxxxxxxxx>]

Useful for HV DC filter caps.  Also commonly used for voltage doubler
circuits.  With each mot producing 2 kV Erms (on the average) , and the
microwave tube requiring 4-5 kV, most mots employ a voltage doubler
circuit.  With rectification it gets the DC potential up to approx 5.6 kV
DC.

Some Tesla experimenters run their coils on direct current, so the 5.6 kV
gives a respectable potential to fire the spark gaps.

If you use the mots with a rectifier, or a voltage doubler circuit, be sure
to provide for adequate bleeder capacitors on the caps to prevent powerful
shocks.

Dr. Resonance




On Sat, Aug 22, 2009 at 5:04 PM, chuck <asimov@xxxxxxxxxxxx> wrote:

> I have nothing useful to provide here but I have another question to add to
> Joel's list. What are those HV caps in a microwave oven useful for anyhow?
> Every time I harvest another MOT I also keep the cap, just in case. Is the
> clutter worthwhile?
>
> Chuck
> Hannwa Falls, NY
> (motto: get me the hell out of here!)
>
> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
> Of Joel Torgeson
> Sent: Saturday, August 22, 2009 6:19 PM
> To: Tesla Mailing-list
> Subject: [TCML] Tuning, Capacitors, and Spark Gaps
>
>
> 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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