Re: the wierdest thing is happening!

["Tesla list" <tesla-at-pupman-dot-com>]

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

Tesla list wrote:

> Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

> Coils retaining a charge, and even coils being drained of static charges
> and recharging again many times by themselves, was the subject of
> discussion a few months ago.

	Indeed.  Even a week or so ago.

> We think it had to do with "electret" effects in the dielectrics.

	It can be nonobvious whether the voltage/charge is on the _coil_
	(the wire) or on the _form_, the rube.

	(Shall we restart the 'formnel;ss coild discussion...  8)>>)

> I would refer you to the archives but I think they are
> broke :-(  Electrets are a fairly complex electrostatic subject that I know
> little about but that was the result of the previous discussion...  Perhaps
> a web search would tell more...

	I cannot see that electrets are complex.  They are the electric
	'analog' to a magnet.  Roughly, starting with a neutral piece of
	dielectric, subject it to hoigh electric (DC) field.  Some of the
	electrons get permananetly displaced (if the e field is high enough).
	Scientific American published an 'Amateur Scientist' article thereon.
	[fx as dwp wanders over to the bookshelf for the index....]

	Two articles.  Nov 1960, July 1968.
	(Sci-am has a web site.  dunno how much of Amateur Scientist
	is available....)
	Roughly:
		prepare 'trays' to hold molten parafin.
		melted the parafin (makes the electrons a bit more mobile).
		Applied a high DC field.
		Cooled the parafin with the field on.
	Other dielectrics will work fine, eg tesla coil secondary forms.

	The subtle point is Where Does a high DC voltage come from?
	Tuyrns Out there is a thing called 'field ion recitifer'.
	Corona Start voltage depends on a number oif things, including
	polarity.  What this means, in practical terms, is that AFTER
	the ACish excitation, as the coil is powered down, a relatively
	low DC voltage (some 10s of KV...  low by coiling standards...)
	remains.  This can 'charge' the coil _form_.

	Tests:
	fabricate an electrosope & see if a charge remains.
	Ditto with a small neon tube.

	'recharges later' is fairly standard for bulk dieletric
	effects.  Pulling a spark, etc, from the surface discharges
	the surface ONLY.  INSIDE, in the body of the material, charge
	remains.  Given time it will 'equalize' with the surface,
	making more charge acessible on the surface...

	(This is one reason large caps should have bleeder resistors:
	they Keep Eating Charge....)

	Puzzle:
	Not all coils do this.
		Why?
	Difference in top coiil geometry?
	Difference in the coil form material?
		(my pet theory....)
	Phase of the moon?

> Sometimes those charges can be very powerful and painful!!

	Indeed.  I think someone alluded to '20V'.
	A 'static' zap, to be felt, is 1kvish and up. 

> >When I turn off the power and short the capacitors for about 3 minuets the
> >top of the secondary gives a small shock, it can't be more then 20 volts- I
> >used to have electric tape there but I got rid of it and now it gives little
> >shocks. Anyone know what's happening? Oh, by the way, 2.5 inch coil
giving me
> >14 inch sparks ran with one 6 kV 30 ma transformer, and my 6 inch coil ran
> >with two 12 kV 30 ma giving me 35 inch streamers, I am very happy. Started
> >work on my 10 inch coil secondary. Already completed primary for 10 inch
> >coil. Anyone in NYC selling a Pig?

	best
	dwp