Re: Longitudinal Waves

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

Original poster: "Mark Fergerson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mfergerson1-at-home-dot-com>

Tesla list wrote:
> 
> Original poster: "David Thomson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <dave-at-volantis-dot-org>

<snip>

> >Why would connecting the ground sides of each wire 1/3 of a turn, only a
> few percent of the total turns, magically change the current/voltage on each
> winding into 3 phase, when both ends of each winding are connected to the
> same points, and within the same exciting field?
> 
> I don't believe there is any three phase action in the coil.  But it is
> noteworthy that the three wire inductances are slightly different from each
> other.

  It's probably a good idea to note that inductances add
counterintuitively (like parallel resistances IIRC) so your
trifilar coil likely has a different inductance from what you
think it does. Have you tried measuring it? Do you attach all
three outside coil ends together when running it in "single
phase" mode? If not, do you just leave the other two hanging?

  I tend to agree with the "Keep the loonies out!" faction here.
We don't need to rehash all the pure fertilizer that's been
promulgated over the years re: "Tesla's magic coils". However,
the list has shown over the years that there's stuff going on in
TCs that is just not apparent at first blush, or even second
blush in many cases (stored charge in secondary formers,
polarized streamers, the secondary RF ground question, etc.) so I
tend to think we really ought to hash this "new" controversy out
long enough to see if there's any juice in it. One man's
interpretation may not hold up (as it usually doesn't in science)
but we won't know until we look. Just my $0.02 worth.

  BTW, is there any real difference with pancake coils either
wound all the way to the center or not? I understand there's an
optimum width for the coil to get max inductance, but how about
Q?

  (I'm not concerned with the longitudinal/transverse waves issue
at this point, just energy transfer and losses.)

  Suppose I _want_ to take the output from the center as opposed
to the edge winding? I have an idea for a maggie driver
comprising two pancakes in a conducting enclosure and I'd like to
ground the outside turn(s). Taking the secondary output through a
centered feedthrough will be easier than at the edge. The
enclosure will also be part of the capacitance on the secondary
(I think I've figured out how to isolate pri/sec circuitry
electrostatically) so drift isn't an issue.

  Mark L. Fergerson