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Re: Primary inductance
Subject: Re: Primary inductance
Date: Wed, 07 May 1997 11:54:06 -0700
From: "Rick L. Kirby" <rkirby-at-earthlink-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
CC: rkirby-at-earthlink-dot-net
References:
1
Tesla List wrote:
>
> Subject: Primary inductance
> Date: Mon, 5 May 1997 19:33:33 -0400 (EDT)
> From: ADatesman-at-aol-dot-com
> To: tesla-at-pupman-dot-com
>
> I'm having some difficulty measuring the inductance of my primary coil -
> I
> think because of old and crotchety test equipment, but maybe it's just
> stupidity. At any rate, I'm wondering - I have 13 turns of 1/4" copper
> tubing on a 30 degree bank, spreading out from 6 inches to about 25
> inches.
> Does anybody with a similarly-sized primary know its inductance? (I am
> just
> trying to get a benchmark, to see where the problem might lie.)
> Thanks!!
> Aaron Datesman
Aaron
I use the following formula:
2 2
A X N
L= -----------------
8A + 11W
Where:
L= inductance in microhenries.
A= average radius in inches as measured from the central
axis to the middle of the winding.
N= number of turns in the winding.
W= width of coil winding on one side in inches.
center axis
|
|
o o o o o | o o o o o <---- coil cross section
|
|----a-----| |---w---|
|
Note: This will get you in the ballpark for flat or 30 deg. styles.
I calculate 64-65 uh for yours if I visualized yours right.
You can also download several programs and spreadsheets to
do this for you.
from: ftp://nic.funet.fi/pub/sci/electrical/tesla/
and its sub directories.
safe coiling
Rick Kirby