RE: Formula for Flat Spiral Coil

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

Original poster: "David Thomson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <dave-at-volantis-dot-org>

I made an error in my post.  The formula I use is

L(mH)=(NR)^2/8R+11W

This is the formula I'm having trouble with.

Dave

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Friday, March 01, 2002 2:51 PM
To: tesla-at-pupman-dot-com
Subject: Formula for Flat Spiral Coil


Original poster: "David Thomson by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<dave-at-volantis-dot-org>

What am I missing in this formula?

L(mH)=(NR)^2/8N+11W

N=number of turns
R=average radius in inches
W=width in inches

Figuring for
N=165.2
R=7.063 in
W=13.875 in

L=16529.21cm or 16.529uH

I would have expected the result to be in mH.

In the past I just assumed I wasn't smart enough to do the calculation right
and just divided the result by 1000 to get mH.  But now I'm using MathCAD
and it is calculating exactly as I did.

Should the formula for inductance of a flat spiral coil actually read...?

L(mH)=(NR)^2/(8N+11W)/1000

Dave