Re: Secondary and Capacitor

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, December 21, 2002 11:22 AM
Subject: Secondary and Capacitor


 > Original poster: "Centauri by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<centauri010-at-attbi-dot-com>
 >
 > Hey everyone,
 > I finished winding my secondary two days ago and I've been coating it
 > with  gloss finish oil based  polyurethane since then. Does it matter if
 > there are a few small bumps in the finish?

Bumps are only a cosmetic problem...  would that these be your only
difficulties!<grin>

I am hesitant to sand it for
 > fear of damaging the coil. Also, how precise does the capacitance of the
 > tank circuit need to be?

Not very precise.. you adjust the tap on the primary to tune the coil
anyway, so a 20-30% variation on cap value from the design point isn't going
to be a big deal If you had calculated for a 10 turn primary, it would just
require tuning 2 or 3 turns in or out from the 10 turns.

Ideally I'd like to use MMC caps but due to money
 > constraints, for the time being I think I'm going to go with a saltwater
 > bottle cap. But I'm not sure how to make a cap like this with the precise
 > capacitance I need. Also, I have no way of measuring capacitance.

Just take one of the nominal numbers.. I venture to say that if you were to
search the archives for saltwater and capacitance, you'll turn up some
actual measurements from someone. I think the geekgroup has some numbers for
a saltwater beer bottle cap in a 5 gal plastic bucket..  use those numbers
for now..

Really, there's so many other things that can be fiddled or tweaked, you
might as well get something built and then start adjusting.  Calculating and
measuring to a gnat's eyelash probably isn't worth it, in most cases.