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Re: oops ("Kickback" and untuned coils)
On Sun, 26 Mar 2000 17:30:18 -0700, Tesla List wrote:
> Original Poster: "Edward Wingate" <ewing7-at-rochester.rr-dot-com>
>
> Tesla List wrote:
>
> > Original Poster: "Lau, Gary" <Gary.Lau-at-compaq-dot-com>
> >
> > Hi Ed:
> >
> > I'd like to come to a better understanding of the hazards of coiling to
> > appliances, and in particular, just what are these ill-defined demons.
> >
> > I don't understand your suggestion that an untuned coil is more prone
to
> > sending HV transients over the AC line. My current thinking has it
where an
> > untuned coil is simply not efficient at transferring the primary energy
to
> > the secondary, so the energy languishes in the primary tank circuit for
a
> > longer than desired time, burning up energy in the gap and putting more
> > cycles and wear and tear on the tank capacitor. But I don't see any
> > mechanism for this energy to get back to the AC mains any more-so than
in a
> > tuned coil. While the duration of each "bang" ringdown is longer, the
> > magnitude of any coupled transients would be no greater.
> >
> > Regards, Gary Lau
> > Waltham, MA USA
> >
>
> Gary,
>
> An untuned coil will produce transient voltage spikes/peaks in the
primary tank
> that are much higher in amplitude than a properly tuned coil and the
> untransfered energy does not just "languish" in the tank circuit, it
finds it's
> way back to the "mains" through the gap and transformer.
I believe this is very possible myself. Back around 1993 I started building
towards an eventual magnifier design when the first component was a large 10
ft diameter coil with only 43 secondary winds at one inch spacing, with
about 2 winds primary. This coil was interacted with another coil also of
1500 ft of 14 gauge wire, but it was a twenty inch diameter with adjacent
windings. Back then I didnt know what I was doing,(some people swear this is
still the case!)but I had calculated the primary values of Inductance by a
mistaken formula. I used L =N^2*A^2/9A+19B instead of N^2*A^2/9A+10B so both
coils were horribly mistuned. I had made these coils with no top terminal
capacities, and just wanted see what the arcing between the coils would do.
I had noticed that I could get thicker white discharges resembling a
lightening discharge from the top terminal back to itself on the secondary
back to 1/3 of its length where the soldered connections between 500 ft
coils were taped with electrical tape. This may have been about a powerful 8
inch bolt back to itself on the secondary, while that single coil itself
only produced about 3 inch violet discharge at end of wire. Running this
coil outside my families tavern resulted in credits being erased off the
jute box, so something was definitely going back up line, as no filters were
used, only some small rf chokes of the NST outputs which kept burning up.
Now when I reacted the large and small coils together they would arc to each
other even when the polarities of the primaries were reversed, obviously the
correct configuration gave the better discharge, but I couldnt figure at
that time what was going on. I grounded the larger diameter secondary coil
to the gas mains, the smaller one at its location, these grounds were then
about 25 ft apart. In a properly tuned system we might imagine that when
coil A borrows electrons from the earth, coil B secondary returns them in
its polarity action when the coils are operating in maximum mutual
inductance with magnetic agreement. However this was not the case in the
mistuned system. To make a long story short about 12 hours after on/off
operations for about an hour the closest lightening arrestor on the street
happened to explode, leaving our street without power. The cause of this was
never determined by the power company, and caused discerned neighbors to
report me to the police for questioning. I wonder if this was just an
untimely coincidence? How could a transient line voltage come back 12 hours
later with such enormous volumes of current? I assume that is impossible.
HDN
Granted, a properly
> tuned coil will produce a certain amount of kickback too, hence the need
> for EMI
> filters on the line feed, but not to the extent that an untuned or badly
tuned
> coil does.
>
> Harry Goldman, editor of the TCBA Newsletter once printed a letter from a
> newbie
> who wanted to know why there were SPARKS ARCING across the slots in the
WALL
> OUTLETS in his home when he fired his newly constructed Tesla coil! How
long do
> you think a microwave or any other solid state device with microprocessor
> controlled displays or functions would last if plugged into those
outlets?! If
> there were sparks across the outlets, what could be happening inside the
> walls!!
>
> Ed Wingate RATCB
> Brockport, NY USA
>
>
Binary Resonant System
http://www.insidetheweb-dot-com/mbs.cgi/mb124201
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