Bill Turner writes:

On 7 Dec 2003 04:21:04 -0800, Winfield Hill
wrote:

Bill, it's one thing to say a coil's reactance is non-linear, but it's
another to assert its inductance varies with frequency.

Both statements are true and easily provable. A simple air core coil
which measures one microhenry at a low frequency may have an inductance
of several millihenries (or even henries) when near its self resonant
frequency.


No, it does not. I'm afraid you are using the word "inductance" in a
different way from everyone else

It's a simple law of physics; there is no way around it.
And *above* the self-resonant frequency, the choke actually behaves like
a capacitor, believe it or not.

Yes, because at high frequencies the current goes through the
capacitance of the coil rather than the *fixed* inductance.

(Uh, by the way, you do know who you are arguing with, right?)...



--

John Devereux

I read in sci.electronics.design that John Devereux
wrote (in ) about 'Winding coils', on Sun,
7 Dec 2003:
I'm afraid you are using the word "inductance" in a
different way from everyone else

It would be better to say 'equivalent inductance', being the value L -
1/(w^2C). L = true (series equivalent) inductance, C = self-capacitance
(treated as lumped in parallel with L) and w = 2[pi]f = angular
frequency.

Resistance ignored, as irrelevant at this level.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!

I read in sci.electronics.design that John Devereux
wrote (in ) about 'Winding coils', on Sun,
7 Dec 2003:
I'm afraid you are using the word "inductance" in a
different way from everyone else

It would be better to say 'equivalent inductance', being the value L -
1/(w^2C). L = true (series equivalent) inductance, C = self-capacitance
(treated as lumped in parallel with L) and w = 2[pi]f = angular
frequency.

Resistance ignored, as irrelevant at this level.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Interested in professional sound reinforcement and distribution? Then go to
http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!