Re: Primary Coil Design
Subject: Re: Primary Coil Design
From: msr7-at-po.cwru.edu (Mark S. Rzeszotarski)
Date: Fri, 29 Mar 1996 23:50:11 -0500
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>>From jim.fosse-at-bdt-dot-com Fri Mar 29 01:16 MST 1996
>>>From MSR7-at-PO.CWRU.EDU Thu Mar 28 11:13 MST 1996
>> What appears to be happening is that the electric field produced
>>by the toroid reduces proximity effects in the coil, thereby raising the Q
>>of the secondary. This is probably due to the linearization of the 1/4 wave
>>voltage rise. What I mean by this is that the capacitive top hat reduces
>>the phase angle by which the secondary must operate at to achieve 1/4 wave
>>resonance. We need 90 degrees of phase shift for 1/4 wave, but the toroid
>>reduces this to perhaps 50-60 degrees along the coil, if a large toroid is
>>employed to make up the difference.
> A thought occurred to me while reading this thread. The toroid
>acts like a shorted turn, N inches above the primary, this decouples
>the top portion of the secondary,from the primary, and allows it to
>act as a magnifier coil.
Jim and others,
I recall that someone examined this hypothesis using a toroid with a
cut across it so it was no longer a closed circular loop. Sorry, don't
remember who right now, will look through my references. Anyways, it did
not appear to affect perfomance a whole lot with the toroidal loop
open-circuited. Has anyone tried this recently, or has the ability to try
it in a fairly controlled manner?
>>. This means that the overall
>>secondary Q is higher, and that losses are reduced. The energy storage of a
>>larger capacitance (E=1/2 x C x V^2) seems to promote more energetic
>>breakout as well.
>The spark acts as a low Z shunt, since P=I^2 * Z, shunting an
>inductance (secondary coil) does not produce the large current need
>for high power, energetic, sparks. The C of the toroid, however, does
>provide this when it is shunted with a low Z.
True, and a good point.
Mark S. Rzeszotarski, Ph.D.