(Re) Wire Length (fwd)

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Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Tue, 19 Dec 2006 05:05:06 -0500
From: Jared Dwarshuis <jdwarshuis@xxxxxxxxx>
To: Pupman <tesla@xxxxxxxxxx>
Subject: (Re) Wire Length

Hi: Bart

I have not wound any flat secondary (yet). I am wondering if the inductance
can be roughly calculated as:

L =   [4 pi x 10^ -7  x (wire length)sqrd] / [ 4 pi Radius ]

They say that Tesla used wood boiled in linseed oil, I have not tried this.
If i were to do this (for reproduction purposes) my choice of wood would be
spruce or similar softwood. I say this because many hardwoods
(especialy wood from tropical enviroments) have minerals in the grain that
are likely to be somewhat conductive. ( teak is horrible, you can see sparks
when the carbide blade hits the mineral pockets)

Yes racing sparks are fun to look at; but all that effort up in smoke!
With some coils there is a race to get the coil tuned before it destroys
itself ( part of the price you pay for leaving the beaten path I
suppose.....)

Seems like a flat coil would make a rather neat half wave. You could have a
skinny toroid capacitor around the outside. And a sphere or toroid in the
center. With proper ballance you might get the crazy motion of a quarter
wave coil, but restricted between points. ( and best of all; no ground to
mess with!!)

Sincerely: Jared Dwarshuis