"Jasen Betts" bravely wrote to "MIKE ROSS" (13 Sep 03  07:04:40)
 --- on the heady topic of "VEHICLE LED'S"

 MR> Okay, I misread you back there. Well, the signal is probably too
 MR> low frequency and amplitude to be picked up by the amplifying
 MR> stage.

 JB> ??? if it's a click it'll be full of high order harmonics won't it?
 JB> DYM probably too low amplitude for clipping?


The signal I was talking about is the voltage induced when we gently
disturb the magnetic field. It would be an ultra low frequency signal
very close to DC and of low enough amplitude that the input coupling
capacitor doesn't even charge up appreciably so as to pass any of it.

Typically the Barkhausen Effect might be of very low amplitude let alone
cause clipping. It is more likely thanks to the dynamic range of the
amplifying stage that we might even hear it. I'm thinking the Barkhausen
voltage might have an amplitude which is closely related to the field
strength or density. Hey, perhaps this is yet another way to measure a
magnetic field? I never heard of an instrument using this principle. It
might be doable... ;-)

Perhaps the nature of the Barkhausen Effect has another explanation. It
may be caused by quantum effects for example. Its discoverer certainly
wouldn't have known about quantum theory or about magnetic domains so he
certainly had no modern explanation. But we know for example that some
quantities which seem continuous at a normal scale are actually discrete
steps at the quantum scale.

 Mike
 ****

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