[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Variable Capacitance and Inductance

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>

Hi Dave:

> Hi Dave,
> 	With one _not_ tuned by crystals I routinely leave it
> 	on, volume down, turn it up, and there is the BBC on
> 	SW, 'just where i left it'.  With another such, even
> 	older, i was listening to 'Radio Australia' (Properly: ABC
> 	Australian Broadcasting Company  But that confuses people
> 	in the US, with the OTHER ABC) one day.  Next day i snapped
> 	it on and there they were.  (Both to a site in Eastern MA,
> 	USA...)
> Just because change _can_ happen does not mean change _will_ happen.

> It could very well be that your turn on your radio someday when

> there is a geomagnetic storm and you get a different station.

	It won't.  Geomagnetic effects, while strong, are not
	that strong.  Solar effects can change which transmitter
	is received (cf 'skip', 'ionosphere' in a good text)
	but not by changing L or C.

	(Hint: there is a good storm on right now, and for the
	next 24 hours....)

> Perhaps also, the frequencies you are listening to would never be

> changed due to the inductance values used in the set's oscillator.


> Tesla did not claim a small electronic inductor would have a great change in
> inductance.  His claim was for a large tin foil ball wrapped around a hollow
> wooden form and dangled around 100 feet off the ground.  And the claim he
> made for this large ball was that there would be small changes along the
> order of 1.6%.

	I believe Malcolm commented on the details.

> The 50% per foot claim was specific to being inside a damp wooden building
> using the large tin foil ball.

	Repeat the exercise, using a modern meter.