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Re: Racing Spark Prediction

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Dmitry,

At 09:47 AM 5/5/2006, you wrote:
Hallo Bart.

about the new subj line - no one on this list can explain what the racing
sparks are and from where they are comin from, so how you can predict the
thing such that you don`t fully understand?
else plz supply a link to Richie Burnett or whatever else page, where
i can read something sensible about it ; )

"I" don't quite understand racing arcs either. I used to think it was do to pure transformer action when the coupling is close. A ten turn primary at 20kV vs. say 400 turns in the lower 10 inches of a coil form. That might push 800kV into a 10 inch section. But Paul and others seem to think it has more to do with harmonics. They are probably right ;-)

Richie's site is here:


Paul's site and papers:


btw - have you experienced in person something like this racing beauty:


? there is no any conical or even solenoidal primary, but top load is
a way too small : )

btw 2 - 12 Jul 2005 Steve Coroner (^_^) said, that "FANTC can't do the
plot of the voltage distribution up the resonator when it's excited on
only one of its resonant mode - the algorithm that draws the voltage
profiles has built in the assumption of a spark gap driver that
excites all the modes at once. So the plot is a mix of (mostly) the
two lowest modes, which I believe have totally different profiles."

does this mean that i`m fooled every time when i see a nice, almost
linear 45 deg voltage rise from bottom to top of my secondary,
independently from what form of primary or value of coupling i use?
coz where is then horrible nonlinear voltage distribution with max at
bottom of secondary, that Steve believe is the genuine reason for
racing beauty formation? : )
or this  voltage profile is valid only for uncoupled secondary? can you
wrote a little proggy that would do such plots for any situ? it is not
for "coilers" of course, but maybe you already have it ; )

Paul as some dynamic time domain movies:


Here is a paper too:



btw 3 - i downloaded fantc "Updated 12/12/05" - why the heck i can`t
put (or leave) zero value in "DEFINE SECONDARY - Bottom Height" field?
when i do this i get runtime error on line 194 "s_height1 - definition
is missing", but when i enter say 0.001 in there and then change this
value back to zero at once - the program works fine?

> Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

> I agree, coupling is easy to measure and the AC current method has
> always been my choice. 2 DMM's are helpful (V and I concentric
> readings). But John mentioned some inaccuracy with higher k coils. I
> can't verify it easily, but if there's a concern, then calculating it
> should resolve any concern.

can you (or John) supply any physical explanation of why high k is
different from low k - in principle, or what the reason for such
innaccuracy anyway?

K should work in all cases. However, that assumes a perfect setup where the floor, wiring, top toroid, etc. do not interfere with the two coils. There may also be interference from strong local AM radio stations that a capacitor and resistor could fix if needed.



You would need tens of MV to break 1/4" acrylic.
20-05-1998 (c) Antonio Carlos M. de Queiroz