RE: eddy current with secondary coil

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

Original poster: Thomas <tom-at-pwrcom-dot-com.au> 


 > Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net>
 >
 > Malcolm,
 >
 > If you choose a wire gauge 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.
 >
 > 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
 >  >

I have the same problem.

I want to build a mini coil with a 2" former for the secondary using at
least 1000t of 28 AWG wire (aspect ratio ~6:1).

But the (excellent) javatc design tool recommends using 24AWG because of the
skin depth due to operating frequency and the expected current.

To do that with the same former will push the aspect ratio well over 10:1
for 1000t, or if I stick to a 6:1 aspect ratio I only get ~600t.

So I'm going to go ahead with the 28AWG wire and see how it turns out.

Tom L.