Re: Getting zapped by my unpowered Secondary

["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>


> > > I have just completed the build of a 2.5" coil, and have
> > > experienced a strange problem. When I grab hold of the
> > > secondary to adjust the height for coupling purposes I
> > > get a fairly painful zap. I am wondering if anybody else
> > > has seen this and what the cause may be. I assume it must
> > > be some sort of parasitic capacitance formed by the wire
> > > in the coil and one of the dielectrics involved in the
> > > construction, with the ambient air-to-ground forming the
> > > other plate. If so which dielectric is involved (coil
> > > form, wire insulation, sprayed polyethylene)? And why
> > > haven't I heard of this before from some other coilers?
> > > I have solved the problem for now by wrapping my entire
> > > secondary in Saran Wrap. This was a good solution and it
> > > is working well now but I would still like to know what
> > > is happening.

	This has been discussed at length, previously.
	There is a stanard effect when a dielectric takes a (quasi)
	permananet charge, check 'electrophorus' or 'electret'
	for related effects.  Roughly, a high electric field will
	semipermananetly displace electrons in the material.
		(that is, the chock is technically from the form
		rather than from the secondary, as such.)

	One might think that the 'ac'; natuere of the tesla secondary
	would preclude such things, this was my initial reaction.  A bit
	of digging turns up the fact that the voltage at which corona
	forms varies with polarity.  This means that there is a
	noticiable resdiual DC component.  (look up 'field ion
	rectifer' or close to that.)  Tesla seems to have used this
	effect in x-ray tube experiments, and had it in mind for
	his (quasi) particle beam weapon designs.

	best
	dwp