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Re: [TCML] Poly thickness



Hi David,

david baehr wrote:
thats what I was wondering ,....a spaced wound coil has less inductance , But increasing the dia. would bring the inductance back up ?
would a spaced wound also be less likely to have racing arcs ?? a 4" dia. COIL , wound tight with #26 might perform as an 8"dia. coil spaced wound (same wire , same winding length ) ? but with an electrical advantage of turn to turn breakdown and MAYBE fewer racing arcs ??? dont know if that all makes sense :-( ? in other words, if ya wanna space wind,..make a BIG FAT secondary ??

Some things occur with space wound coils that appear to look good, but some don't. Assume a 900 turn coil, 4.25" dia. for closewound and the same coil at 450 turns for spacewound.

DC and AC resistance are half that of the closewound.
Q increases slightly.
Reactance is half.
Frequency doubles.
Distributed capacitance remains the same for both.
Inductance is reduced by a factor of 4.

The closewound coil will attempt to charge the topload to double the voltage of the spacewound coil. This is significant. I ran both coils looking at the voltage distribution (changing turns only). Here's how it came it out (btw, default coil in Javatc).

http://www.classictesla.com/temp/closewound.gif
http://www.classictesla.com/temp/spacewound.gif

In order to achieve the same performance as the closewound coil above, you would have to double diameter, length, turns, toroid, primary, etc. for the same spacewound ratio.

I don't see an advantage and this larger coil would be even better closewound.

As far as racing sparks? Well, I speculate both coils would be similar. The volts per turn hasn't changed from at least that standpoint and both distributions are rather linear due to their h/d.

Take care,
Bart

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