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RE: Strange shock (fwd)



Of course it's during the operation of the coil that the charge is formed,
nothing to the contrary was suggested.  For the uncoated coils that you've
seen this effect on, either the secondary wire had to have a thin insulating
enamel coating, the charge being deposited on that, or the wire was truly
bare metal, space-wound on the insulating form, with the charge being
deposited on the form between the windings.  In either case, there has to be
an insulating surface on which to deposit the charge.  It's just not
possible to deposit a static charge on a grounded conductor.

I suspect that a heavily polyurethaned coil may be capable of developing a
more substantial charge than an enamel-only insulation coil.  A thicker
layer of whatever would be able to store a higher voltage between the outer
surface and grounded wire below before breaking down.  

I don't have a reference to cite for coronal rectification.  This is not
something I invented or discovered, but has been mentioned several times on
this list. Terry Fritz noted that with his single-shot car ignition coil
experiments, the secondary arcs were consistently and substantially much
more pronounced when the DC-charged primary cap was applied in one polarity
than the other.  This causes the secondary pulse to begin ringing in one
polarity, suggesting that streamer/coronal breakdown occurs more readily in
one polarity than the other - i.e. rectification.

I made no guess as to whether vacuum tube coils would also generate this
effect - don't have one.  Good question!  While I see no reason that coronal
rectification would behave any differently with continuous operation, don't
forget that the peak secondary voltages and power levels in a VTTC are
considerably less than in a disruptive coil, so deposited charges would also
be less and thus not a fair comparison.  Anyone else?

The "equi-drive" configuration is identical to a normal two-coil arrangement
but with the tank capacitor split into two equal capacitors, each connected
to either end of the primary coil, and the gap connecting the other ends.
While this circuit arrangement does appeal to one's appreciation of
symmetry, there is no electrical consequence or benefit to splitting the
capacitor to either side of the primary.  In a series circuit, the behavior
is no different no matter how you sequence the series elements.

Regards, Gary Lau
Waltham, MA USA

		
>Original poster: "Daniel Boughton" <daniel_boughton-at-yahoo-dot-com> 
>
>Gary:
>That is exactly my point!
>
>It is during the operation of the coil that the charge
>is formed! Uncoated coils produce the same effect.
>Therefore, I do not believe it is the varnish. I have
>seen it most prominently in equidrive circuits. By the
>way what is, 'the rectification mechanism of corona'?
>Have you ever experimently proven this as a repeatable
>effect? I would like to see a paper detailing your
>experiements and your scientific conclusions. If this
>were somehow true and not produced from the damped
>ring down charging system, you would see this effect
>on continuous wave oscillators as well. Do you own a
>vacuum tube coil? Is the static charge there from the
>corona? Or is this just a guess?
>
>Regards,
>
>Dan

>> 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