Re: LC III

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Bob (R.A.) Jones" <a1accounting@xxxxxxxxxxxxx>

Hi all,

Just a few more points for completeness. There were two other reasons that
were used negate transmission line theory.

1. That it was connected to wire length. This was incorrect it had nothing
to do with wire length or the propagation velocity along an open wire.
There is also significant evidence that Tesla knew this too. What may have
confused things here was the habit of radio engineers and many books on the
subject of using empirically derived velocity correction factors for coils.
Similar to the Medhurst C confusion.

2. That the complete telegraphist's equation where required to be used
because of longitudinal coupling.  This was incorrect. In fact because the
turn to turn capacitance is small (say >20% for isolated coils) compared to
external isotropic capacitance. Additionally the self inductance reduces to
zero for an infinitesimally small section of coil and is irrelevant.  As has
been described previously its the sum of the mutual inductance function that
is relevant. Which very conveniently is approximately the inductance of the
coil divided by its length. (for coils whose length is small compared to
wavelength ie typical Tesla coils)

Robert (R. A.) Jones
A1 Accounting, Inc., Fl
407 649 6400
----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Sunday, March 27, 2005 8:22 PM
Subject: Re: LC III


> Original poster: "Bob (R.A.) Jones" <a1accounting@xxxxxxxxxxxxx>
>
>   Hi all,
>
> Around 2000 the prevailing view on the list was that secondary coils some
> how oscillated as lumped elements.
> It was believed that there was some new or unknown physics involved in
this.
> This view was perpetuated by several misunderstandings and
> misinterpretations principally related to the following..
>
> 1. Medhurst C with secondary L gave the correct frequency.
> 2.No transmission model gave the correct frequency.
> 3. No phase shift along the coil.
>
> Though it was clear from Medhurst's paper that his Medhurst C was a small

> correction that had to be added to a much larger parallel capacitor and
not
> the isotropic capacitance of the coil. This was ignored or not understood.
> Even when experimenters asked why the measured isotropic capacitance was
not
> even close to Medurst C it was assumed to be a measurement problem. The
> lumped model using Medhurst C gave approximately the correct answer so it
> was assumed that the coil some how oscillated that way and that it was
> nothing to do with propagation velocity, standing waves, transmission line
> theory or 1/4 wave effects.
>
> Apparently because Medhurst C was believed to be the isotopic capacitance
of
> the coil it was used in transmission line equation which inevitably
produced
> the wrong frequency. It was shown that when the correct isotropic
> capacitance was used in the transmission line equations they produced
> similar results to the Medhurst C lumped model and in some cases more
> accurate.
>
> There was a misunderstanding that a standing wave had phase shift along
its
> length which it does not. This was said to prove the lumped model and
> disproof the transmission line or propagation velocity concept or 1/4 wave
> effects There is no phase shift along a standing wave. There where and are
> many examples of coils being used as delay lines but that was ignored.
>
> A year or two later rigorous finite element models where produced that
more
> accurately predicted the frequency and the old debate about transmission
> line models, propagation velocity and 1/4 wave theory was put to one side.
>
> What seems to have happened is that 1/4 wave theory and transmission line
> theory became not applicable again to the secondary while the finite
element
> analysis results were accepted. This appears to be a half way house where
> the old antagonists of the lumped model (the Corums) can still be vilified
> while accepting the accurate results of the finite element analyses. I
guess
> old beliefs are hard to dispel.
>
> Though not all of what the Corums said was accurate what they said about
the
> secondary as a 1/4 resonant transmission line was correct and they said it
> when many on the list believed that secondary oscilated as lumped elements
> with infinite propagation velocity.
>
> There will never be a last day to transmission line theory in connection
> with secondaries because without it its very difficult to explain the
> resonances of the secondary.    Even the finite element analysis produces
> forward and back ward wave velocities and though its become inconvenient
to
> refer to the fundamental resonance of the secondary as a 1/4 wave
resonance
> never the less that's what it is.
>
> An other point that is frequently made to suggest that transmission line
> theory is not applicable is that the isotropic capacitance is not uniform
> and that therefor uniform transmission line theory does not apply. That is
> strictly correct but misleading. The fact remains that even if the
> capacitance is not uniform the resonance is a standing wave and to
> understand the standing wave and its higher order modes you need to
> understand the propagation effects and reflection i.e. transmission line
> theory.
>
>
> Robert (R. A.) Jones
> A1 Accounting, Inc., Fl
> 407 649 6400
> ----- Original Message -----
> From: "Tesla list" <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Sunday, March 27, 2005 9:20 AM
> Subject: Re: LC III
>
>
>  > Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
>  >
>  > Hi,
>  >
>  > Transmission line theory was popular in the 80's especially with the
>  > Corums.  But I never saw an example where they actually got the
analysis
> to
>  > work...  They were on the right track, but the devil was in the
>  > details...  The true system was too complex...  The Tesla coil is a
very
>  > "non" uniform transmission line and the coefficients one comes out with
>  > look pretty much like a simple inductor or an impossible mess....  It
fell
>  > apart in the 90's and was replaced buy lumped parameter models which
are
>  > still often used.  Today, computers can grind fantastic amounts of data
to
>  > really get down to the true operation of the Tesla coil.
>  >
>  > http://www.classictesla.com/fantc/fantc.html
>  >
>  > I don't think anyone even tries to study coils with transmission line
>  > theory anymore even with fancy computers.  All the modern programs and
>  > techniques either are lumped parameter and Medhurst based or use finite
>  > element analysis.  There very high accuracy is undeniable!!
>  >
>  > I think transmission line theory's last days are summed up in these two
>  > pieces from five years ago...
>  >
>  > http://www.ttr.com/corum/index.htm
>  >
>  > http://www.pupman.com/listarchives/1999/October/msg00428.html
>  >
>  > So I join with Paul (but perhaps with a bit more gentle tone ;-)) and
> agree
>  > that if your still trying to use transmission line theory with Tesla
> coils,
>  > your 10 - 20 years behind...
>  >
>  > Cheers,
>  >
>  >          Terry
>  >
>  >
>  > At 06:22 AM 3/27/2005, you wrote:
>  > >Jared wrote:
>  > > > you are misapplying transmission line theory.
>  > >
>  > >No I'm not.  You're ignoring all the evidence of measured
>  > >coils, and apparently can't be bothered to learn any of the
>  > >relevant theory.
>  > >
>  > >Have you measured a coil yet?  Your faulty assumption of light
>  > >speed propagation along wires will put you around 50-100% out
>  > >on frequency measurements.  Measure a solenoid and see that you
>  > >are wrong and EM theory is correct.
>  > >
>  > > > This is the likely reason for the accuracy of our model in
>  > > > predicting node locations in multiple wave length coils.
>  > >
>  > >Again we see the bottom line of your argument - the nodes
>  > >are in the right places.
>  > >
>  > >Let me use a rope analogy.  Vibrate a rope between two anchors
>  > >to form some high resonance with multiple half waves, and note
>  > >the node positions.  Then, increase the rope tension so that
>  > >the propagation velocity is increased.  Set the rope oscillating
>  > >once more in the same mode (now at a higher frequency).  The
>  > >nodes will be in the same locations.   In the same way, your
>  > >observations of node locations say nothing about the propagation
>  > >velocity.  You saw the nodes where you expected them and
>  > >erroneously concluded that the operating frequency and velocity
>  > >must therefore be as predicted - an elementary mistake.
>  > >
>  > > > it does bother me that you would describe velocity factors of
>  > > > up to twice the speed of light, pretending that this was some
>  > > > sort of mainstream science.
>  > >
>  > >If you'd bothered to read earlier extensive replies attempting
>  > >to correct your errors, you would already understand that a
>  > >velocity factor with respect to the wire of greater than unity
>  > >doesn't imply that signals are travelling the wire at greater
>  > >than light speed.   It shows instead that the field disturbances
>  > >we call "signals propagating through the coil" are guided by the
>  > >wire into a spiral with a pitch greater than that of the winding.
>  > >
>  > >If it makes you happier, define a velocity factor with respect
>  > >to the solenoid length instead, to get factors around 0.001
>  > >or so.
>  > >
>  > >This is just an example of a much larger class of phenomena in
>  > >physics in which EM propagation velocity is reduced (sometimes
>  > >severely) in the presence of charged particles, both free and
>  > >bound.  Inside a metal like copper, for example, the velocity
>  > >is down to walking pace!
>  > >
>  > > > Richard Quick told you this about 10 years ago, you should have
>  > > > listened to him.
>  > >
>  > >He's never told me anything. What on earth are you talking about?
>  > >
>  > > > The rope resonance models we have employed are not jokes.
>  > >
>  > >Sure, rope models are handy, sometimes.  But they don't have the
>  > >properties of an EM field.  For example, each piece of rope only
>  > >affects its immediate neighbours, via tension, whereas charges in
>  > >a wire affect each other at a distance via their fields, especially
>  > >so when they are brought into proximity by coiling.  All those EM
>  > >effects are missing from the rope model.  They determine the
>  > >inductance and capacitance and propagation velocity, taking the
>  > >place of tension and mass in the rope model.
>  > >
>  > >If you push the rope analogy too far, you end up with predictions
>  > >for a rope, not a coil!
>  > >
>  > >Please, measure some coil frequencies before you make more of a
>  > >fool of yourself.  Then go learn the theory that predicts those
>  > >frequencies.  Otherwise, people will laugh at you for ignoring
>  > >measurements and rejecting well established theory - all because
>  > >you are too stubborn to recognise that you made some elementary
>  > >mistakes.
>  > >--
>  > >Paul Nicholson
>  > >Manchester, UK.
>  > >--
>  >
>  >
>
>