Re: Capacitor construction

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

Original poster: "Robert by way of Terry Fritz <twftesla-at-qwest-dot-net>" <obiwan1186-at-sunflower-dot-com>

Those might work, but I would go with geek caps. They are extremely cost
effective, and durable; perfect
for TC use. they might take a while to get though. I placed my order in the
middle of july and still
don't have my caps yet, but it will probably be worth the wait.

Tesla list wrote:

> Original poster: "Daniel Barrett by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <dbarrett-at-clearcube-dot-com>
>
>     Thanks, everyone for the thoughts on the glass plate caps! So, as I
> understand this, glass will work but it's a bit lossy at these frequencies
> and can tend to 'crater' after a while. I guess I'm now sold on the MMC idea
> :)
>     So my next question is what are the optimal (Okay, the best bang/buck
> coefficient) caps to choose?
> I'm looking at my trusty DigiKey catalog, and have come up with these
> Panasonic metalized polypropylene film caps. These are rated for 1600 VDC
> (500AC) with a dissipation factor of .2 above 10kHz and are recommended for
> pulse applications. One hundred of these can be had from Digikey for $.97
> each (P10507-ND).
> Would these be a good choice to build the MMC from?
>
> Thanks for the help!!!
> db
>
> > Glass will work, but it's lossy, and must be placed in oil for
> > best results.  The dielectric constant is high at about 6, but
> > the Q depends on the dissipation factor which is rather poor
> > for glass.  You'll probably lose about 15% in spark output
> > length using a glass plate cap vs. a low loss cap.  The
> > primary tank in a Tesla coil runs in a low Q mode anyway,
> > but glass caps increase the overall losses.  If you want to
> > insist on building your own caps, an alternative would be
> > to used rolled polyethylene, or flat layers of polyethylene.
> > Such construction gives good results and low losses,
> > and can be built very cheaply if you can obtain the parts
> > for free, or almost so.  Such caps are bulky however.
> > Glass caps, despite their shortcomings do work, and that's
> > what Tesla himself used.  He used glass bottles which used
> > to fail on a regular basis.
> >
> > John Freau
> >
> >
> >