RE: Cap Formulas (fwd)

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Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sat, 9 Dec 2006 23:26:45 -0500
From: "Lau, Gary" <Gary.Lau@xxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: RE: Cap Formulas (fwd)

Mylar, a.k.a. polyester, is a very poor choice for a dielectric in Tesla
coil capacitors.  While a low power coil may get by using Mylar, a
pig-powered coil will toast such a cap before you can say "What's that
smell?"  It's not an issue with thickness, puncture voltage or
dielectric constant - it's the dielectric losses, gauged by the
"dissipation factor" at RF frequencies.  Some common, acceptable
dielectrics are polypropylene, polyethylene (LDPE), and glass.  

A 0.2uF cap is a very large cap for a DIY rolled cap, and as will most
others, I would strongly suggest abandoning a rolled cap using any kind
of dielectric for an MMC.  I have made two laborious attempts at rolled
caps using LDPE in mineral oil, and both have suffered the same
unpleasant fate.

Regards, Gary Lau
MA, USA

> Date: Sat, 9 Dec 2006 04:04:16 -0500
> From: Victor Yoo <vlysvc@xxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Cap Formulas
> 
> Can any one help me with calculating the required area (length of
plates) to
> make a rolled cap using the following;
> 
> 20" wide by XX long aluminum flashing
> 
> 24" wide x .007" thick x XX long Mylar film
> 
> With a dielectric constant of 3.0 and a puncture voltage of 7500v I
figure
> that I can make two 0.1uf @ 52.5kv for a total of 0.2uf for my 14.4kv
10kva
> pig.
> 
> I will be immersing the roles in mineral oil.
> 
> Any ideas or comments?
> 
> Victor