[TCML] Capacitor calculator?
mrapol at verizon.net
Thu Sep 17 15:24:14 MDT 2009
----- Original Message -----
From: "Quarkster" <quarkster at att.net>
To: "Tesla Coil Mailing List" <tesla at pupman.com>
Sent: Thursday, September 17, 2009 2:39 PM
Subject: Re: [TCML] Capacitor calculator?
> Paul -
> How well did the metal Leyden jars work?
> Herr Zapp
If you mean metal jars laminated with dielectric, not so well. I tried
layering on plastics of various kinds, shellacked paper, neoprene (!) and
even liquid tool grip rubber. I then put a layer of metal foil on the
outside of that. This worked, but feebly. I suspect the integrity,
smoothness, and dielectric strength of the coatings was not the best. My
dream was to find metal and dielectric cylinders that fit neatly and
naturally into each other. The closest I came was 16 oz peroxide bottles and
12 oz soda cans. Lemonade canisters are best, but they require heat to
soften the plastic to allow the can to fit.
I tried a lot of metal fillings. Two of the most interesting were copper
scrubber pads and copper clad BB shot. I put 2-3 scrubber pads in a 500ml
HDPE wide mouth vitamin bottle (the sort called in the industry a "packer"
bottle). I used a length of 10 gauge copper wire inserted in the mesh and
connected to a brass top terminal. The outside of the jar got the usual
aluminum tape. These usually gave me about 150 to 200 pF. The same bottle
2/3rds full of BBs was good for 250-300pF. These were pretty heavy. Using
BBs does allow to vary the capacitance at will by mounting the jar sideways
with interruptions in the exterior coating. By rotating the jar (and the BBs
inside) you can vary the capacitance. This is more useful in crystal radio
I tried the usual 5 gallon bucket jar. My results were inconsistent. I got a
lot of arcing and perforation of the dielectric, which on a jar that big was
rather, um, exciting. I think a better grade of plastic would give better
results, but once I fixed on the soda can design I haven't gone back to the
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