# Re: Racing Spark Prediction

```Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Dmitry,

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So the lower two thirds of the coil is normal and the top 1/3 is reverse wound...
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The current is less at the top of the coil but there would be some reverse voltage in that case... If we assume a linear voltage profile with maximum voltage per turn at the base and practically 0 at the top and we fold the top third...
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Thinking.... #%&:-p  Integrating  |\:-p   ....

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So if the total normal voltage is 1, the total voltage across any part of the coil starting at the base is X and assuming a height of 1:
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Vt = 2 x (X - X^2 / 2)

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If we put in 2/3 for x we get 88.9% of the voltage still at the top!!!! :-))))) That is not a significant hit if it stops the racing arcs and allows tighter coupling!!! The DRSSTC folks really like high coupling so this might be very useful to them!!!!
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Note that the top third might be somewhat shorted by the top terminal which is basically a lossy shorted turn.... Just to make it more messy %:o)
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Cheers,

Terry

At 11:00 AM 5/17/2006, you wrote:
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```folded resonator as one of the possible cures from racing sparks

Paul wrote: nothing

ok, Paul - i ask you here (to screen poss mail problems) third time -
what is the problem with a folded resonator concept? this would be my
last question to you at all if not answered. you give me no choice : )

Terry wrote:

> I think the problem is when you reverse wind part of the coil, the
> performance would also drop way down.  You can get ride of any
> harmonics by making the coil out of dirt too but that is no fun.

i can`t see how it can be a problem - you`ll lose a very small part of
total sec inductance only, since mutual inductance between parts is
very small, as well as mutual/coupling between pri & reversed part of
the secondary.
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