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Re: Fw: Fw: Space winding



Hi Antonio & all-

I have no experience with conventional L-C-spark gap Tesla coils (mine is
solid-state) so I hope you will excuse any misunderstanding.  Do you have
a reference for the derivation of the equation you quote?  In my view, a
Tesla coil secondary (or that of any transformer, resonant or not) "sees"
only magnetic flux; it is immaterial what primary apparatus produces that
flux.  But in the conventional T.c., that flux starts out high and then
exponentially diminishes because of the discharging of the primary
capacitor through the spark gap.  Thus, the flux applied to the secondary
correspondingly diminishes over time.  But during that time, the
secondary remains a resonant entity--until a spark occurs, that is. 
There ensues a race, so to speak, between the tendency of the secondary's
voltage to rise due to its resonance and the action of the primary's
voltage (and thus, its flux) in exponentially diminishing.  If the
primary flux did not so diminish, then the secondary voltage would rise
faster and to a greater amplitude.  Perhaps that relationship is what
leads to your equation.

In my T.c., the primary excitation is constant during each pulse-burst
and thus, while the fundamental behavior of the secondary is exactly the
same, an equation such as you cite is inapplicable.  (And it clearly is,
on the face of it:  I have no primary "C".)  Because, as I think, the
secondary's fundamental action is always the same, I would think that my
analysis, if correct for my case, is correct for all.

Ken Herrick

On Sat, 12 Aug 2000 19:47:22 -0600 "Tesla list" <tesla-at-pupman-dot-com>
writes:
> Original poster: "Antonio Carlos M. de Queiroz" 
> <acmq-at-compuland-dot-com.br> 
> 
> Tesla list wrote:
> > 
> > Original poster: "Kennan C Herrick" <kcha1-at-juno-dot-com>
> > 
> > So...It's now morning & I see still another error in my postings 
> of
> > yesterday:  In 2.1 the square root of 0.5 is, of course, 0.707 and 
> not
> > 0.25.  Thus, in 2.2, Q will increase to 0.707/0.25 = 2.8 times 
> what it
> > was.  And from that, in 3.1, the new voltage is going to be 0.5 x 
> 2.8 =
> > 1.4 x the old.  So space-wound is better!  Plus, even better than 
> that by
> > my reasoning re the frequency.
> 
> I am reading with interest your comments, but I notice a possible
> problem: Q only affects significantly the output of a CW coil. A
> capacitor-discharge coil has its output voltage fundamentally
> limited by the energy stored in the primary capacitor at each
> operation cycle. The output voltage cannot exceed:
> Vomax=Vin*sqrt(C1/C2)
> where C1 is the primary capacitance and C2 the total secondary
> capacitance, what includes the secondary self-capacitance and
> the terminal capacitance (a bit smaller that the sum of both, as
> separately measured or calculated). Higher Q is certainly good,
> however, because losses in the coil will be smaller. The limit
> value is only reached in a lossless Tesla transformer.
> 
> Antonio Carlos M. de Queiroz
> 
> 
> 
> 

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