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RE: grounding - this doesn't make sense - wire size

Subject:  RE: grounding - this doesn't make sense - wire size
  Date:   Sat, 10 May 97 08:55:12 UT
  From:   "William Noble" <William_B_Noble-at-msn-dot-com>
    To:   "Tesla List" <tesla-at-pupman-dot-com>


consider a simple series circuit containing a capacitor, an inductor,
and a 
spark gap, representing the secondary, torroid, and the gap from the
torroid 
to whatever the secondary is connected to.  Now, initialize the
capacitor to a 
high voltage by using mathamatical magic.   Now, let a spark (e.g. a
pulse of 
some shape) jump the gap.  If the spark has a current I, then the same
current 
must be seen at both ends of the gap, that is clear.  By that analysis,
it 
would seem that the secondary must also, by Kirkov's law, carry the peak
spark 
current.  We know this is not the case, so there is something wrong with
that 
type of analysis.

What I think the problem is: the gap from torroid to ground isn't a
simple 2 
terminal circuit, or even a complex 2 terminal circuit, it is in fact a
3 
terminal circuit with one terminal being it's connection to the torroid,
one 
it's connection to the "ideal ground" and one it's connection to the
base of 
the inductor.  If thought about this way, there are some non-linear 
components, but there is also a capacitor (perhaps representing the
Cself of 
the coil?? plus some kind of atmospheric factors???) which is not part
of the 
secondary copper path itself, which already connects from the torroid to 
ground, and it is this capacitor, in series with the torroid that
carries the 
bulk of the strike current.

Does this seem right??? If yes, then it would say that yes, max current
could 
be somewhere other than at the base of the secondary, but it doesn't
suggest 
that a huge ground wire is needed.  The reported information about the 
benefits of bigger wire make sense because of reduced inductive losses -
after 
all if it's expensive you will use less of it, and big fat wire or strap
is 
more expensive and harder to work with (hence routed more directly) than
some 
#22 hookup wire.

-----Original Message-----
From:   Tesla List 
Sent:   Thursday, May 08, 1997 1:20 PM
To:     tesla-at-poodle.pupman-dot-com
Subject:        RE: grounding - this doesn't make sense - wire size

Subject:  RE: grounding - this doesn't make sense - wire size
  Date:   Thu, 8 May 97 14:01:22 UT
  From:   "William Noble" <William_B_Noble-at-msn-dot-com>
    To:   "Tesla List" <tesla-at-pupman-dot-com>


ok, now this is interesting, if correct - I can see the need to keep the 
ground "solid" at RF freq driving the need for short wire and thick wire 
although it seems to me that putting a large steel plate on the floor
might 
work better at RF freq (does anyone do this - like run the coil
connected to a 
drip pan or something?).  Anyway, I don't see how the current, once in
the 
wire, could build up somewhere in the ground, after all, Kirkov's law
still 
applies.

[Bill]  snip==== 
Someone please correct me if I am wrong, but essentially the
point of highest current (the true high current node of the 1/4 wave)
is not necessarily at the base of the coil, but rather down in the
ground system itself.  The wire that the coil is wound with does not
carry the absolute maximum current developed by the coil, even at
the base.  Thinking of it this way, the entire ground system becomes
an integral part of the coil, and the need for a heavy connection
becomes obvious.


Charles Brush
http://www.foundrygroup-dot-com/cbrush