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Re: More on Z=SQRT(L/C)

Hi Ken,

> Original Poster: Kennan C Herrick <kcha1-at-juno-dot-com> 
> 
> More beating on the (not quite dead) horse:  I'm still troubled by the
> referenced expression.  That's an expression for the >characteristic
> impedance< of certain electrical networks.  It doesn't seem to me that
> that has a lot to do with the resonant network of a Tesla coil. 

> Characteristic impedance, in ohms, is generally defined as the impedance
> of a transmission line of infinite length; or else, the value of a
> network's load resistance that causes the impedance looking into that
> network to be the same as that load resistance.  Who knows what a load
> "resistance" might be for a Tesla coil?

Shunt impedance varies from (Q^2+1) x ESR (unloaded) down to ??

       One might well describe the secondary as having a 
characteristic impedance given that it is a distributed circuit. In fact, 
you can terminate a TC secondary in its Zo at each end and see for 
yourself whether it works or not. If it does, a source = Zo connected 
to one end should result in a critically damped response when Zo is 
connected between the other end and ground shouldn't it? The 
formula I derived can easily be derived from a Tx line point of view.
Ref: Radio Engineering, 2nd ed.  Ch III, p71 by F.E Terman DSc.

> Malcolm Watts wrote that, for the lossless case at resonance, Z = Xl =
> Xc...but shouldn't that be, Z = Xl - Xc?  Whether at resonance or no,
> doesn't Z always = the vector sum of Xl and Xc (absent loss), that sum
> being zero at resonance?

My argument would be that regardless of Z at resonance, the 
individual components of a resonant circuit retain their 
characteristics.
    If I were to connect a charged capacitor across an inductor, the 
current does not instantly rise to a maximum but takes time 
comensurate with the resonant frequency of the circuit according to 
the values of L and C.

> ...And does it matter a whole heck of a lot when most of you guys (&
> girls, I've noted) are clobbering your secondaries with all kinds of
> messy shock-excitations from your 19th-cy.-style apparatuses?  (Speaking
> as a solid-state-er, myself...ahem...)

You're right - sparks are much more fun.

Regards,
Malcolm

> Ken Herrick
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