Re: More Capacitor Ideas

Subject:      Re: More Capacitor Ideas
      Date:   Fri, 13 Jun 1997 20:09:05 +1000
      From:   Peter Electric <elekessy-at-macquarie.matra-dot-com.au>
        To:   Tesla List <tesla-at-pupman-dot-com>
References:   1

Tesla List wrote:
> Subject:  More Capacitor Ideas
>   Date:   Thu, 12 Jun 1997 14:10:20 -0400
>   From:   "Thomas McGahee" <tom_mcgahee-at-sigmais-dot-com>
>     To:  <tesla-at-pupman-dot-com>
>     CC:  "Tesla-2" <tesla-2-at-emachine-dot-com>
> Fellow Coilers,
Snip snip and more snip!>

> Note that all the thoughts about a DRY Tesla Coil Capacitor are just
> that: thoughts. I have *not* actually built such a beast. But the
> more I think about it, the more I like the idea!
> Hope the thoughts are useful and trigger even bigger and better
> thoughts!
> Fr. Tom McGahee

Your thoughts on building a dry Cap are food for thought but as I have
some experience spraypainting (especially boats) I'd like to add the
following observations. "Varnish" is a fairly general term but here it
usually refers to enamel based paints. These paints generally cure by
forming an impervious layer on top while staying slightly wet
underneath, resulting in a fairly durable finish as it is able to move
slightly without cracking all the way through. This is probably not a
good property for TC capacitors as the cap will remain full of
unevaporated solvent.

On the other hand, the latest batch of two pack polyurethane paints or
even a good grade of epoxy resin, (as used in boat construction) might
be ideal for this kind of service as it not rely on exposure to air for
its cure. The only thing to watch is that most of these materials shrink
in volume by more than 10% as they cure and this sometimes causes the
material to shrink away from the object you are trying to encapsulate. I
have often experienced this when casting objects in clear epoxy resin. A
trick that is often used by the professionals is to place the thing in a
vacuum chamber until the resin cures.

In any case the idea is definately worth a try. I will try and find the
time to build a small one and see how it goes.

Cheers from the land of sinking bubbles,

Peter E.