Re: Big Spark Induction Coil

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

Original poster: "Kurt Schraner by way of Terry Fritz <twftesla-at-qwest-dot-net>" <k.schraner-at-datacomm.ch>

Antonio -

Completely agreed! I was just expressing it a little differently. You
remember: in my 21 December private mail to you, covering the same
question about appearence of the oscillations within the ringdown, I
wrote:

"In my understanding, the spark is just implementing a kind of structure
change (the 50k resistor [Rem.for TCML:representing the secondary spark
in Microsim] also beeing almost a short circuit), where we no more see a
coupled 2-resonant-circuit-system L1C1+L2C2, but only one of a single
L1C1 circuit. My simple 
f1 = 1 / { 2pi * sqrt [ L1 * (1-k^2)* C1 ] } 
correlation formula, which is based on a bare simple transformer model,
points in the same direction, at least for relatively tightly coupled
induction coils, like my one. As seen, it fits the data quite well."
...may be, it got a little bit lost, within the bulk of other
information exchange. 

Well, even in the "sim", when displaying the secondary voltage (accross
the sparkgap), at first, we observe a very high peak (i.e. 16kV for test
24A), and then essentially low voltage accross the spark, till the high
f1 oscillation has ceased, when the f2 oscillation appears. This leads
to the second part of your posting: The tuning of the coil, including
primary and secondary LC's, as well as coupling, can be implemented to
probably optimal values, just for creating the first energy transfer
from prim' to sec' -and highest voltage- BEFORE secondary spark
breakdown. Did I get you about right? 

There's just a 3rd thing, which also triggers my interest: the
capacitive loading of the secondary, without generating sparks. As
,essentially, a "capacitive shorting" of the secondary, it produces
comparable first f1 ringings similar to a spark (see i.e.test 33A). But
it's as well forming the L2C2 resonant circuit, and as such, makes the
system behaving differently than with spark. The observed frequencies f1
and f2 concur with those fI and fII calculated from A.Bowers's idealized
induction coil theory, while, with a non-capacitively loaded, but
sparking coil, this is not generally the case. I'm yet pondering about
it...

Cheers,
         Kurt Schraner

P.S. I'm afraid, Terry must stop this thread, getting too much off
topic?


Tesla list wrote:
> 
> Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
> 
> Tesla list wrote:
> >
> > Original poster: "Kurt Schraner by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <k.schraner-at-datacomm.ch>
> 
> > I don't think, you're misinterpreteing my pic's. I'm myself wondering
> > about the long duration of the higher frequency "f1" part in the
> > oscillograms. But this oscillation behavior is experimentally true: you
> > can watch(live) the extension of the "f1"-time by manually shortening
> > the spark electrode distance. The same behavior was obseved recently,
> > using just an ignition coil. However: may be, the spark itself is
> > lighting and extinguishing many times, during this perjod of some 3.x
> > ms. The jacobs-ladder photos of my inductor seem to lead, to suppose
> > short sparking times, as very distinct sparks can be observed, while the
> > coil was operated at 50Hz. The pulses, however, were generated by short,
> > about 1ms lasting, capacitor discharges from the "dimmer".
> 
> I think that I have figured out what happens.
> A key point is that you are looking at the primary current. The spark
> practically short-circuits the secondary, stopping the energy transfer
> by coupled oscillations. The spark is reignited for some cycles just
> by "transformer" action of the system. When there is not enough energy
> to reignite the spark, the coupled oscillations restart, without sparks,
> until the remaining energy in the system is dissipated.
> There is a tuning condition where when the first spark appears,
> at the first peak of the secondary voltage, there is no energy in the
> primary. The tuning is then optimal, and all the energy is transferred
> to the spark at once. The distributed nature of the secondary may
> change this a bit.
> 
> Antonio Carlos M. de Queiroz