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RE: Secondary Inductance



F W Grover (Inductance calculations Working Formulas & tables) gives a 
formula for a correction factor for single layer coils with spaced 
windings. The correction factor is subtracted form the usual figure to 
get the true inductance. According to Grover, the correction is 
unimportant in most cases, but he was looking at more usual uses of 
inductors!  Heres' his formula anyway, hope it helps

Correction = 0.004 x Pi x coil radius x number of turns x (G + H )

Where G = 1.25 - loge(2 x wire diameter/winding pitch)

Winding pitch is the center to center distance of the turns.

And h is a tabulated number depending on the number of turns, given as 
0.3360 when n=750 and 0.3364 when n=1000


----------
From:  Tesla List [SMTP:tesla-at-pupman-dot-com]
Sent:  13 April 1999 19:06
To:  tesla-at-pupman-dot-com
Subject:  Secondary Inductance

Original Poster: "Steve Young" <youngs-at-konnections-dot-com>

Hi list,

I would like to know if the inductance of a secondary space wound to 
a
given length with a given number of turns has about the same 
inductance as
if close wound with larger wire but the same number of turns?

For example, suppose I close-wind an 8 inch diameter coil with a 
winding
length of 30 inches with 1000 turns of #21 wire.  If I space wind 
another
coil with 1000 turns of # 23 to the same 30 inch length, is the 
inductance
approximately the same as the close-wound coil?

If someone has a Wheeler-like equation which has an additional 
parameter
representing  spacing of the winding of a TC secondary, I would 
appreciate
you posting it on the list.

Thanks,

Steve Young