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Re: Variacs, HV Jell, and LTRS Caps
Terry,
CAREFULLY heat up a small test batch of paraffin,
and slowly add scraps of polyethelene plastic, allowing the scraps
to dissolve. It is very useful to cut the scraps up into thin
strips, as this increases the surface area and enhances the
speed at which the poly will dissolve. Do not overheat the
paraffin. Thin poly dissolves MUCH faster than thick poly!
Remove a reasonable sized sample, label it and let it cool to
room temperature. Add more poly or paraffin to the remaining
test batch and repeat the procedure several times until you
have achieved the desired consistency at room temperature. Mix
up another SMALL test batch using the ratio previously
determined to be best, so as to verify the ratio. Once you have the
desired ratio, you can mix up batches of any convenient
size.
Note that you should measure the ratio of poly to paraffin
BY WEIGHT, as that is easier than measuring the volume...
assuming, of course, that you have a means for measuring
the weight in the first place.
Keep a record of your experiments and post the results to the
list :)
Fr. Tom McGahee
----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Variacs, HV Jell, and LTRS Caps
> Date: Sunday, May 16, 1999 6:07 PM
>
> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
> Hi All,
>
> I am building a new control box and I was going to get another variac.
> Superior Electric and Staco come to mind and I was just wondering if one is
> better than the other in any way? Staco is a bit more expensive but if
> they are somehow better it would be worth the few extra dollars.
>
> Also, I am working on a new MMC cap design that will require that they be
> submersed in oil. I am running them above their ratings (in the "enhanced"
> mode :-)) taking advantage of the fact that "I know things" :-)) Since oil
> is such a mess, I was wondering if mixing mineral oil and say paraffin
> would produce a jell that could be heated to flow but would solidify like
> grease when cooler? The jell would not be a dielectric but more of an
> insulator and mounting medium to put the caps in nice PVC cases. The
> advantage would be it would not run, spill, leak, etc. If this works, I
> can make a 5.6nF cap for about $25!! If it doesn't, I don't want to have
> to clean up a bunch of oil :-)) This will test if the manufactures ratings
> really do mean anything in Tesla coil applications. I am running just over
> the edge in voltage and current but theoretically they should hold up very
> well. My present MMC runs soooooo cool I think it may be a waste of money
> to over design these things too much. More exploration of their limits is
> called for. Since I have all my stuff modeled, I can predict RMS currents
> and voltages very well so as to push the rating of the parts "gently"...
>
> I have been running a small coil off a 27nF (larger-than-resonant-sized
> (LTRS)) cap with a 15kV/60mA transformer the last few days. All seems to
> be working as expected and the output seems much better than my old 17nF
> configuration. Much more to learn about this. I think this is a very
> promising area despite the theoretical complexities. Much more to come
> about this...
>
> Any thoughts are welcome...
>
> Terry
>