RE: Somewhat of a newbie..

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-compaq-dot-com>

A vacuum cap is the best possible dielectric so far as losses are
concerned.  They would be ideal for a tesla coil tank cap, except that
the capacitance needed in a tank cap is far in excess of what can
reasonably be achieved with vacuum caps.  A spark gap-type tesla coil
using a 15kV/30mA NST will typically use a tank cap from .005 to .01uF.
If you tried to construct this using your 12pF vacuum caps, you'd need
417 to 833 in parallel.

Greg Hunter http://www.angelfire-dot-com/ga3/tesla/ reports that 12 oz beer
bottle caps are good for about 811pF each.


Regards, Gary Lau
MA, USA

>About 6 months ago I finally built my first coil. I've
>since had ALOT of questions and I remembered that the best
>minds colaborate on this list.. Anyway, my question
>involves capicitors.. I started out using saltwater caps
>made from beer bottles.. but I realized that I had no way
>of knowing how much capacitance I had.. is there any way to
>test them or is there some general default value per
>bottle? I also ordered 4 caps vacuum sealed in a glass
>envelope rated 12pF -at- 30kV each .. they're absolutely
>beautiful.. each one is about the diameter of a soup can
>and about 8 inches long.. will these work in coiling
>applications? The glass envelope is about 1/4 of an inch
>thick and the lugs on the ends are very hefty.. they look
>like they'd survive a nuclear war...