Re: Capacitance of a coil

To: tesla-at-pupman-dot-com
Subject: Re: Capacitance of a coil
From: "danial stocks" <diode-at-hotmail-dot-com> (by way of Terry Fritz <twf-at-verinet-dot-com>)
Date: Sun, 17 Jan 1999 15:22:13 -0700
Approved: twf-at-verinet-dot-com

> 
>> A further note in this book states that the important parameters in 
the coil
>> capacitance are the diameters of the winding and the ratio of the 
pitch
>of the
>> winding to the diameter of the bare wire.  The capacitance is 
practically
>> independent of the number of turns.  Of course, the wire insulation
>thickness
>> and dielectric constant  and the form on which the coil is wound will 
alter
>> the capacitance of the coil.
>> If you try this, Let me know how it works.
>> Mike
>
I agree... I derived some eqns earlier today in an attempt to 
approximate a coil by modelling a capacitor with flat toroidal 
electrodes. It seemed in my eqns that if the spacing between turns and 
thickness of wire rato is held constant, and diameter of coil held 
constant (measured from the CENTRE of the wire - ie inside dia + 1 
winding thickness) then capacitance per unit length of coil should be 
pretty much constant...

If this is actually the case, and as inductance of a coil is prop to 
square of no of turns to a fair approximation, then the self resonance 
of the coil should be proportional to no of turns, or inversely 
proportional to wire thickness !(with length, dia, pitch const.)

______________________________________________________
Get Your Private, Free Email at http://www.hotmail-dot-com