RE: Strange shock (fwd)

[Terry Fritz <twftesla-at-uswest-dot-net>]

This may be a good point.  Consider this:

Since negative arcs tend to propagate much better than positive arcs.  The
objects in the surounding area of a coil may tend to gain a net negative
charge.  Now when you turn off the coil and touch it you get a shock.
Touch it again and you get another shock.  Often you can repeat this for a
while.  We assume the coil is charged, but it may actually be fairly well
grounded.  The person is fairly insulated and may simply be getting
recharged again and again from standing in the charged area of the coil.

Rubbing the coil seems to help but this may be due to induced charges that
build up.  Also, the inside and plastic parts of the coil may do a lot of
recharging too.  

Is is truely strange to sit there and try and discharge the coil over and
over just to have it keep recharging again and agin.  It also hurts ;-))

Cheers,

	Terry


At 03:09 PM 7/15/00 -0700, you wrote:
>
>I agree with Gary that static charges can accumulate on dielectric surfaces
>such as the TC secondary coil. There is a simple test for this type of
>charging. Rub a piece of paper with a sheet of plexiglas to electrify it.
>Take a Ne2 neon lamp and move the two leads around on the paper. The lamp
>will flash indicating groups of charges on the paper.
>
>Can these varying charges be the reason for the extra long random spark
>output from the TC secondary coil terminal?
>
>John Couture
>
>---------------------------
>
>
>-----Original Message-----
>From: Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent: Saturday, July 15, 2000 9:46 AM
>To: tesla-at-pupman-dot-com
>Subject: RE: Strange shock (fwd)
>
>
>Original poster: "Lau, Gary" <Gary.Lau-at-compaq-dot-com>
>
>Hold on.  The distributed capacitance of the secondary has nothing to do
>with these shocks.  The shocks are from a _DC_ static charge deposited on
>the surface of the secondary's polyurethane (or whatever) coating.  The DC
>charge occurs due to the rectification mechanism of corona - that it occurs
>more-so in one polarity than the other.  What's underneath this charged
>layer of polyurethane - a coil of wire or a solid tube of copper - doesn't
>matter.  The distributed capacitance of the secondary can't matter as this
>capacitance only matters at high frequencies.  At DC, distributed
>capacitance can hold no charge.
>
>Gary Lau
>Waltham, MA USA
>
>		-----Original Message-----
>		From:	Tesla list [mailto:tesla-at-pupman-dot-com]
>		Sent:	Friday, July 14, 2000 10:48 PM
>		To:	tesla-at-pupman-dot-com
>		Subject:	Re: Strange shock (fwd)
>
>		Original poster: "Daniel Boughton"
><daniel_boughton-at-yahoo-dot-com>
>
>		Antonio:
>
>		While it may be true that ionized air store pockets of
>		charge heavily insulated coils have significantly
>		higher distributed capacitance resulting in a lower Q.
>		This distributed capacitance coupled with the terminal
>		capacitance is what accounts for the an inductor's
>		self resonant frequency. To find the value of the
>		distributed capacitance one must measure the coils
>		self -resonant frequency and inductance. This can then
>		be applied to the coil's series resonance formula to
>		determine the coil's distributed capacitance value.
>		Note this is to be done without the terminal
>		capacitance. The distributed capacitance will be seen
>		not to be as low as you might think. Secondarily, the
>		charge in the coil is minute until the larger
>		capacitance offered to the coil by touch is presented
>		by the human body. The result is an in-rush of current
>		to stabilize the voltage. This in-rush (reactive
>		effect)is often much higher than the residual charge
>		which accounts for the formation of a spark. This is
>		the phenomena of a capacitor anyway. That is a
>		capacitor will supply any current necessary to keep
>		the voltage across its terminals at equilibrium. It
>		doesn't create energy it just generates current as a
>		function of time. In otherwords, I can generate 0.5
>		Coulombs per second or use the same charge to generate
>		0.5 Coulombs per millisecond. The rate is determined
>		by the value of the capacitance while charge can
>		remain constant.
>
>		What does his coil resonate at anyway 250KHz? 100KHz?
>		What's the value of his inductance? What is the value
>		of the capacitance needed to cause his coil to
>		resonate at that frequency with that value of
>		inductance? Not so small. This is why F.E. Terman
>		states mathematically that the highest Q helical
>		resonantor is found when the winding length of the
>		coil is equal to or less than its diameter.
>
>		Dan
>
>
>
>