RE: Experimental tesla coil using Radio Shack Megacable Speaker wire as primary

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

Original poster: "Harvey Norris" <harvich-at-yahoo-dot-com> 


--- Tesla list <tesla-at-pupman-dot-com> wrote:

 > Original poster: "Steve Conner"
 > <steve.conner-at-optosci-dot-com>
 >
 >  >Particularly the
 >  >bothersome project of creating a tesla coil with
 > the
 >  >meager power available from my AC converted car
 >  >alternator.
 >
 > Hi Harvey,
 >
 > Your set-up using resonant rise to boost the voltage
 > from an alternator
 > sounds like it would work perfectly well. However I
 > don't think you need to
 > bother adding a third 0.12nF cap as your Tesla coil
 > tank capacitor.
 >
 > I reckon all you need to do is connect the Tesla
 > primary coil (with series
 > spark gap) across the 1nF capacitor that you use to
 > resonate the induction
 > coil. When the 1nF cap rings up to a high enough
 > voltage it will fire the
 > spark gap and act as the TC tank cap. Once the
 > energy is dissipated the gap
 > will quench and the cap will recharge by resonant
 > rise at 480Hz.
I am accustomed to thinking that it is the combination
of L and C that determines the primary resonant
frequency, which is why I thought some capacity,
albeit very small, should still be used to make a
primary frequency near 330,000 hz, to match the
resonant frequency of the secondary. In this case here
if the 1 nf were to match with the 2.3 mh primary
inductance, the combination might be in ten fold
error, a resultant resonant freq near 33,000 hz.
 > I have seen a similar set-up in one of Tesla's
 > patent applications.
 >
 >
 >  >I can create two of these voltage rises in near
 >  >opposite phasings
 >
 > In this case can't you arrange things so the two 1nF
 > resonating caps are
 > connected together at a midpoint?
Yes, and the entire circuit still resonates since the
path of the capacitive reactances in series becomes
halved, but the pathway of the two high induction
coils in series gets a doubled inductance, so the new
combinations of L and C values still resonates to the
source frequency. Of course an arc gap can be placed
at this middle connection point. For the simplest
first generation source frequency resonant circuit,
this has special ramifications for quenching the arc
between 180 phased series resonances. As long as the
arc is not firing, opposite voltage rises are being
formed on either side of the arc point.  However when
the arc presents itself as a connection point, (where
we can also simply place a short there to see the new
actions of the circuit), this changes the entire
circuit in such a way that it no longer exists as two
inversely phased series resonances providing opposite
voltage rises, now the two circuits unite to form a
solitary figure 8 parallel resonance, with the
inductive and capacitive reactance currents sharing
the same pathway in opposite directions (in unity of
currents, where since the reactances themselves are
180 phased relationships, but opposite enter and exit
points makes this a double negative yeilding
unity)across the short. Placing a short at the arc gap
will show this aspect,(doubled currents across short)
the entire circuit now acts with 4Q squared more
impedance then what the inversely phased series
resonances provided.  Thus far less current will enter
the circuit when the short is in place, because of the
rise of impedance. Additionally the outside branches
no longer supply resonant rise of voltage, the action
reverts to one of resonant rise of amperage, but
because the impedance has gone sky high, this is of
little consequence. Inside the circuit, q times more
amperage exists than is inputed by the source, but
this is still q times less current then would exist
for the series resonant case. (This is the reason that
the new figure 8 tank has the q squared term for
comparing the impedance differences between the
examples) So the consequence for having an arc gap
instead of a short to accomplish these conversions is
that as soon as the gap fires, BOTH the amperage AND
voltage of the supply are highly reduced, leading to a
very superior quenched arc gap, that will want to
extinguish itself as soon as the firing takes place.
This can lead to very high BPS rates at the gap.  In
the particular case here with providing a second
generation source frequency resonance, attached to the
midpoints of the first generation source frequency
resonance, the first generation source frequency
resonance using 12 ohm, .15 henry components has a
combined q factor in the mid 40's. The 2nd generation
source frequency resonant circuit can boost this
voltage rise another 8 fold, or 16 fold using a
special modification using the third phase to provide
a mutual inductance between 1st and 2nd generation
resonances. The net result of this is that using large
collections of inductances resonating at 480 hz, a
circuit with a combined q of around  40* 16 = 640
becomes available, meaning that the alternator
inputing only 15 volts, can create almost 10,000 volts
across the C2 value of 1 nf.  When two of these are
made using two interphasings, (the term describing the
2nd generation source frequency resonance), and an arc
gap is placed between the interphasings, if a voltage
meter is across the stator input voltage, it will
quickly be incapacitated. A scoping investigation of
the stator voltage input shows that reverse voltage
signals occur back towards the stator voltage input,
probably every time the arc gap fires.  This would
imply that the interphasal arc gap system is trying to
push amperage the wrong way back through the source of
emf. In particular interest here, I would note that
Radio Shacks 22-801 digital meter actually has a reset
button inside its guts, so that if transients like
this disable it, the meter still may be recoverable. I
have found that just about anything involving arcing
with alternator source frequency resonances can be
very damaging to meters, because of these type of back
emf transients. The versatility of having three phases
available from the alternator means that many
different things can be tried. I have even tried a
ferromagnetic pole pig from one phase, and used the
other two phases to create source frequency resonant
voltage rise, and combined the two together for a
tesla type primary arc gap; a la marc metlica's
triggered arc gap idea using three electrodes; but the
source frequency resonant voltage rise was greater
then what the pole pig could deliver, and again this
created destructive transients back to the source.  At
one time I had three high induction coils all making
these high voltage 2nd generation voltage rises. Three
20 inch neons could be lit in either delta or wye
configurations. But I could never get a triple arc gap
to function, because of inherent balance problems.
Once two of the voltage rises are usurped  by an arc
gap from two of the three phases, the third phase
appears to loose its effective voltage rise. This will
have future ramifications of trying to make a three
phase tesla coil system, as now I have almost three
secondaries prepared for that experimentation, but
first I got the problem of just making just a single
TC work from resonant voltage rise, so that remains
pure speculation at this point in time.  Looks like
I'm going a bit off topic here. I will try some
combinations this weekend for making the single TC
work from an alternator, using just source frequency
resonant voltage rise.  I also finally bought a larger
3 phase high voltage transformer, so those things can
be of use in the future also, but the WYE
configuration of its primaries causes great inbalance
problems when connected to the WYE configuration of
the alternator source stator.  They say that the WYE
to WYE configuration causes balance problems, and this
is the second time I have seen this happen. Both times
the end voltages coming out from the  three phase
secondary come out in a 1:2:3 ratio.

In previous experimentation with a triple electrode
set up, were the center electrode was designated as
the trigger electrode with its voltage sourced from
the source freq resonant voltage rise, and the outside
electrodes were connected to the alternator driven
pole pig, I found that from pics, many times the arc
is not bridged on both sides from the center, but that
the primary circuit is still excited by that one sided
arc method.  This might be a good point to start from
in attempting to get things to work with just a single
interphased voltage rise. The outside electrodes can
be attached to the primary tesla circuit, and the
voltage rise routed to the center electrode. This
gives a separation between the 1 nf cap used for the
source frequency resonance, and the cap values to be
tried for the tesla primary.  For usage in dual
opposing interphasal voltage rises, a 4 electrode
assembly also seems concievable, this time the center
two electrodes are attached to tesla primary circuit
endings, and the outside terminals attached to the
opposite voltage rises.  There are of course quite a
few things that can be tried here, so I will keep
plugging at things until some kind of result is
reached.
HDN


Then you could
 > connect the TC primary
 > across the two caps in series to get an effective
 > 500pF 20kV tank cap.
 >
 >
 > Steve C.
 >
 >
 >


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