Series resonance/Was: Waveguide TC

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jolyon Vater Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>

Jim,
 >From what I understand an open-ended 1/4 wave transmission line is
series-resonant circuit; series resonant tuned circuit have 90 degree phase
shift between current at
the driven end (low impedance) and current at the terminal end (high
impedance).

A lumped series-resonant circuit can be visualised as an inductor L and a
capacitor C
in series with a signal source or "generator". Surely there is a 90 degree
phase shift between current at the driven end and the current at the
"terminal" end i.e. current flowing "through" the capacitor?

There is a common belief (incorrect?) that the secondary of a TC is a
series-resonant
circuit - I might be wrong but would this not presume a 90 degree phase
shift between input and output-
whereas observations made on real TCs suggest little or no phase shift
between currents at the grounded and the terminal ends.
Is the "series-resonant secondary" like the quarterwave resonant theory
incorrect
-or is it possible to have a series-resonant tuned circuit with
little or NO phase shift between low-impedance input and high-impedance
output?
Or does the series-resonant voltage boosting effect involve not just the
secondary but
the primary as well -with the primary leakage inductance resonating with a
"transformed" value of the secondary capacitance via the magnetic coupling?

Jolyon



----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, December 13, 2002 6:53 PM
Subject: Re: Waveguide TC


 > Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<jimlux-at-earthlink-dot-net>
 >
 > Not really.. A tesla coil is more of two coupled lumped LC circuits,
rather
 > than a transmission line. The "1/4 wave transmission line" model has
pretty
 > much been discarded (it's fairly easy to show that lots of very well
 > performing TCs don't resemble 1/4 wave).  For that matter, the phase shift
 > between current at the top and bottom of the TC is nowhere near 90
degrees,
 > as it would be for a transmission line.
 >
 >
 > At 08:06 AM 12/13/2002 -0700, you wrote:
 > >Original poster: "Jolyon Vater Cox by way of Terry Fritz
 > ><twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
 > >
 > >
 > >----- Original Message -----
 > >From: "Tesla list" <tesla-at-pupman-dot-com>
 > >To: <tesla-at-pupman-dot-com>
 > >Sent: Friday, December 13, 2002 2:38 AM
 > >Subject: Re: Waveguide TC
 > >
 > >
 > > > Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>"
 > ><jimlux-at-earthlink-dot-net>
 > >
 > > > Which is what a Tesla coil is, is it not?
 > >Jolyon.
 > >
 > > >
 > > > One can also make a transmission line that's about a quarter
wavelength
 > > > long and drive it with a suitable matching network at one end which is
 > > > shorted, leaving the other end open. The line acts as an impedance
 > > > transformer using Zout*Zin = Zline^2, and if Zin is really small, Zout
is
 > > > really big, implying high voltage for a given power (or, another way
of
 > > > looking at it, you set up a standing wave in a high Q resonator (i.e.
the
 > > > transmission line).
 > > >
 > > >
 >
 >
 >
 >
 >