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

["Lau, Gary" <Gary.Lau@xxxxxx>]

Additionally, 80(!) of pretty much any kind of cap in series is going to have a very high equivalent series resistance (ESR), since resistance is additive.  Resistance in the primary circuit is a performance killer.  If cost is a concern, a beer bottle/salt water cap will do much better.

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of David Speck
> Sent: Saturday, August 22, 2009 8:00 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] Tuning, Capacitors, and Spark Gaps
> 
> Joel,
> 
> Well, for starters, microwave oven caps do not have the proper
> characteristics for a TC tank circuit.  They are designed for use at 60
> Hz, but are unacceptably lossy at TC tank frequencies.  The relatively
> low value internal bleeder resistors will also rob you of power,
> especially working with only  a 9 kV NST.
> 
> The rest of the description sounds promising.  Check the TCML archives
> about MMC capacitors.  Those have had an excellent success rate.  Not
> exactly cheap, but the will work.  MWO caps will not.
> 
> Dave
> 
> Joel Torgeson 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.
> 
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