Re: eddy current with secondary coil

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

Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz> 

Hi Chris,

On 7 Oct 2003, at 18:48, Tesla list wrote:

 > Original poster: "chris swinson" <exxos-at-cps-games.co.uk>
 >
 > HI Terry, all,
 >
 > thanks for the links, will check them out :)
 >
 > IS there anyway to find the proximity effect for optimal distance for the
 > secondary turns ? There might be some simple rule or guide which states the
 > effect is double the wire size or something ?  I would like to try a better
 > space wound coil though the proximity effect will be greatest as the wire
 > gets closer, as it gets further it must be less, but does this mean at 1mm
 > spacing its 50% less and 2mm its 70% less or does it just stop at 2mm
 > spacing, very confusing I think...
 >
 > Chris

Here's a simple rule that's worked well for me:

Given that you know the *lowest* frequency that your coil is going to
operate at, for a closewind, make the wire diameter = 6 skin depths.
For a spacewind halve the wire diameter so you now have the same
number of turns and turns per inch but a spacing between the turns =
1 wire diameter.

Malcolm