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Re: Lumped vs. T-line - You be the judge...
Hi Terry and all,
I can not quote your post because I deleted it by mistake.
> original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
You suggest that a secondary may look like a short transmission line with a
series L.
Do you mean that the distributed L C and R can be approximated by that or
.its an equivalent circuit.?
The lumped model I have sent you is an attempt to represent the true
distributed L C and R as ten lumped stages it is not an equivalent circuit
in
the sense that it has not be reduced to a minimum required to reproduce the
behaviour of a coil. A major difficulty, well at least for me, with the
lumped view is that there is apparently no equivalent model that
correctly represents the distributed L C and R and resonates at more than
one
frequency. Your suggestion appears to have a similar problem.
Assuming your L is at the driving end then your equivalent circuit will
resonate when ever the transmission line looks like C which will be at
frequencies less than its 1/4 wave length. This is directly equivalent to
an end loaded line with C. I have not done the maths but I assume the phase
shift caused by the L/input impedance will be frequency dependent. So I
suspect this may be a good equivalent circuit that represents both the multi
resonances and dispersion of a secondary as opposed to a tuned circuit.
Because its an equivalent circuit for the input to output and does not
necessarily model the true distributed L C and R it will not necessarily
model the distributed voltage of the secondary ( just like the turned
circuit
equivalent circuit). However it would have the advantage of more
accurately
modelling the effects of the initial transient when the gap fires. It may
need a fiddle factor on the output voltage as it may not be possible to
simultaneously have the correct input impedance for the primary, the correct
output impedance and resonate at the right frequencies with the right phase
delay.
I previously suggested one or more resonance periods for a good FF.. That
is
incorrect due to the dispersion and other reasons. My best advice now, is as
you suggested, use a long time sample so the end effect is less preferable
decayed to zero if you have sufficient samples.
What is the maximum number of samples you can take?
How long In samples to decay to say 10%?
How does your simulation program model a transmission line? (this is a hard
one)
Regards Bob
Regards Bob