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Re: Bang the rocks together harder lumpophiles
Hi Terry,
Why do you think part of the coil has negative C or zero C. This is very
strange to me
Regards Bob
-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: 22 April 2000 19:19
Subject: Re: Bang the rocks together harder lumpophiles
>Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
>Hi Bob,
>
>At 12:48 AM 04/22/2000 -0400, you wrote:
>>Hi Terry and all.
>>
>>At the input to the coax you have a discontinuity just before the
reflection
>>90deg after it 0deg inpractice the reflection must be spread out a
little.
>>
>>As I have said before its very hard to interpret the time domain signals
>>from impulses or edges. Try digitising it and FFTing it with mathcad then
>>you have the impulse response which is the transfer function.
>
>Since the signals are only repeated once during the capture and the
>digitizing of the scope is high. The FFT of the single event is probably
>too choppy to trust.
>
>http://users.better-dot-org/tfritz/site/misc/Bob12.gif
>http://users.better-dot-org/tfritz/site/misc/Ken04.gif
>
>>For those with out such luxuries it common practice to perform sinewave
>>tests on a linear system because superposition holds i.e. you can treat
all
>>the sine waves independently. It is not true to say that such tests are
not
>>applicable to transients. Transients are just a collection of sine waves.
An
>>impulse has a flat spectrum and an edge has a 1/f spectrum.
>>
>>I am surprised that your coil characteristic impedance (CI) is so high
have
>>you confirmed it by
>>measurement and at what frequency. Perhaps its high by the same
>>factor the wave is slow compared to a standard TM. The CI will be
frequency
>>dependent for the same reason the propagation velocity is frequency
>>dependent i.e. the turn to turn coupling. You cant use the standard
>>equation to calculate it just like the propagation time.
>
>Z = SQRT ( L/C )
>
>L = 22.1 mH
>C = 9.3 pF
>Z = 48748 ohms for the pure T-line equation.
>
>MicroSim can resolve an "average" impedance but that is only some mix of
>the probably wildly varying Z along a real coil. However, MicroSim does
>predict loading effects like frequency very well from this number.
>
>
>>
>>It not a matter of what is realistic its a matter of taking measurements
>>on parameters like propagation delay. This can then be used to build a
>>model which you can then compare in a realistic case. As you have said the
>>standing wave completely dominates the generator signal so its impossible
to
>>make measurements on it. The trick of all experiments is setting them up
so
>>you can accurately measure what you want.
>>
>>I assume you have been using a standard TM model which is not applicable,
no
>>turn to turn coupling. Try the one I will send you its only got ten
elements
>>and only coupling between the stages unlike a real coil that is coupled
>>along its whole length but it should show some dispersion and slow
>>propagation.
>>
>
>I have studied the capacitance in the x,y and z directions along the coil
>but I am not sure I trust those calculations yet. However, it is very
>obvious that a standard T-line model consisting of constant RGLC parameters
>is useless. I think a piecewise model as you elude to is the way to go in
>trying to get the measured results to match some type of virtual model or
>calculation. Since the C component is a little negative for about the
>first 1/3 of the secondary, the T-line models fail. However, that
>capacitance could probably also be taken as zero without much effect which
>would essentially reduce the first 1/3 of the coil to a pure inductor.
>Everything points to that being near to the true nature of the thing.
>
>Cheers,
>
> Terry
>
>
>>Regards Bob
>>
>>-----Original Message-----
>>From: Tesla List <tesla-at-pupman-dot-com>
>>To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
>>Date: 19 April 2000 13:58
>>Subject: Re: Bang the rocks together harder lumpophiles
>>
>snip...
>
>