Re: Flat secondary measurements

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

Original poster: "Paul Nicholson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <paul-at-abelian.demon.co.uk>

Dave Thomson wrote:

> The optimum inductance for a given length of wire will be obtained
> when the average radius is 4/3 of the width. The width of the
> winding will be 6.349" and the average radius will be 8.5".  Total
> number of turns will be 315.9.  The total diameter of the coil will
> be 23.3".  The radius of the coil center will be 5.291".

Darned good - but too good.  You've gone below the minimum pitch of
0.025125 inches by about 20%.  You're on the right lines though.

I've received a couple of good answers, involving both flat and
solenoid coils.  Is anyone looking at any other shapes - spheres,
and more general ellipsoids, and cones?  What's happening to the max
inductance in between the two special cases of flat and solenoid?

>Inductance Contest
>------------------
>You have 426.72 metres (1400 feet) of 24 awg (0.51055mm diam) wire.
>What's the highest inductance you can achieve with it?
>Coils must be single layer, with concentric windings.  The minimum
>allowable pitch is 0.6382 mm (0.025125 inches) which corresponds to
>a spacing ratio of 0.8.
>Answers direct.
--
Paul Nicholson
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