RE: iron coir equation

To: tesla-at-pupman-dot-com
Subject: RE: iron coir equation
From: Sulaiman Abdullah <sulaiman-at-lityan-dot-com.my> (by way of Terry Fritz <terryf-at-verinet-dot-com>)
Date: Thu, 19 Nov 1998 07:49:44 -0700
Approved: terryf-at-verinet-dot-com

Ramsey,
If it's an iron core in a solenoid without a complete magnetic path
(iron bar or wires) then the increase is quite small and depends upon
the geometry of the coil, for a simple solenoid I get about x3
inductance compared to no iron, the gain is from linking the magnetic
flux from all of the turns together.

If the core forms a complete magnetic circuit then you need to know the
effective path length (including air-gaps etc.) to calculate inductance,
and the iron cross sectional area to determine maximum amp-turns before
saturation.

The simple way is to get your intended core, wrap it with
thin/cheap/recyclable wire and measure the inductance, I usually use
resonance with a known capacitance to find L=1/((2 x PI x Freq.)^2 x C),
then scale the inductance as the SQUARE of the turns ratio (3 times more
turns = 9 times more inductance)

If you want more maths mail me off-line      sulaiman-at-lityan-dot-com.my

> Does any one know how to calculate the inductance of and iron core
> coil?
> thanks
> Ramsey
> 
>