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 Gerry,

On 8 Oct 2003, at 23:18, Tesla list wrote:

 > Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net>
 >
 > Malcolm,
 >
 > If you choose a wire guage that allows 6 skin depths, I think you would not
 > be able to put the 1400 turns onto a former with an aspect ratio of about
 > 4.5:1 (at least with an 8 inch coil - that I'm building).  Could you comment
 > on this.

The guide I use guarantees that the secondary will have a good Q
(assuming decent former material). It may well be that one wishes to
trade off secondary Q for primary Q by winding for a lower frequency
for a particular coilsize. I took that approach in my tabletop entry
(yet to be fired - I still have to clear a bundle of semiconductors
etc. from the garage when other activities permit). However, the nub
of what I was saying to Chris was that one can wind a spaced coil and
save money and reduce coil weight in the process without sacrificing
performance or introducing undue complications into the calculations.

Malcolm

 > Gerry R
 > Ft Collins, CO
 >
 >  > 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
 >  >
 >  >
 >
 >
 >