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Re: Bang the rocks together harder lumpophiles

Hi Bob,

It's very strange to me too! :-))  But it appears to be very real...  See
the chart below:

http://users.better-dot-org/tfritz/site/misc/Efield.gif

The blue line represents the E-field in the upward direction.  The read
line represents the E-field along the side of the coil in the X-Y
direction.  Note that the field is negative for the first ~1/3 of the
coil's length.  The bottom of the coil is actually appearing as a lower
potential point due to the surrounding fields and energy is actually being
absorbed by that section.  In effect, the bottom of the secondary is
absorbing electrostatic energy as the coil charges.  I guess that would be
the definition of a negative capacitance??

You can also see the effect in the fields chart.

Cheers,

	Terry




At 01:36 PM 04/23/2000 -0400, you wrote:
>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...
>>
>>
>