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Voltage/Length (fwd)
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From: Bert Hickman [SMTP:bert.hickman-at-aquila-dot-com]
Sent: Monday, February 09, 1998 8:34 AM
To: Tesla List
Subject: Re: Voltage/Length (fwd)
Tesla List wrote:
>
> ----------
> From: Alfred A. Skrocki [SMTP:alfred.skrocki-at-cybernetworking-dot-com]
> Sent: Saturday, February 07, 1998 7:56 AM
> To: Tesla List
> Subject: Re: Voltage/Length (fwd)
>
> On Thursday, February 05, 1998 6:17 AM Greg Leyh
> [SMTP:lod-at-pacbell-dot-net] wrote;
>
> > John H. Couture wrote:
> >
> >
> > > It should be noted that using the equation
> > > Vs = Vp sqrt(Cp/Cs)
> > > can give incorrect results when applied to Tesla coils.
> > [snip]
> > > If the Cs is reduced in the above equation (reduce toroid size) with no
> > > other changes the Vs and sparks can be shown to be greatly increased. We
> > > know this is not true because it is contrary to tests of real coils.
>
> The above is wrong because it does not consider the fact that the
> equation Vs = Vp sqrt(Cp/Cs) refers to the distributed or parallel
> secondary capacitance. The toroidal capacitance is in SERIES with the
> secondary and actually decreases the total secondary capacitance and
> this is why adding a toroid usually increases a coils output.
>
> Ctotal = 1/(1/Csecondary + 1/Ctoroid)
>
> yet it's own capacitance holds the necessary energy for increased output.
>
> > But Vs isn't the the only factor that affects spark length!
> > Real world factors, such as break rate and terminal capacitance
> > both _dramatically_ affect spark length, independent of Vs.
>
> This is definitely true! All these factors influence the efficiency
> of the coil.
>
> > When you increase the toroid size and see longer sparks,
> > Vs has actually _decreased_, but the coils' effectiveness
> > at propagating the spark channel has improved by an even
> > greater amount, due to bigger toroid's improved capacity
> > to provide fast currents to the base of the spark.
>
<SNIP>
Alfred,
Whoops! Got to disagree with this! The toroid capacitance is actually in
parallel with the coil self-C. This is easily demonstrated by the effect
that it has on the resonant frequency - adding a toroid always lowers
the frequency (and, therefore, the peak voltage).
-- Bert --