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Re: Variable Capacitance and Inductance

Original poster: "rheidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>

Dave:  I thank you all for this un-gentlemenly posting. I am slow to see the
concepts in my mind. It appears to me that your studies show a TC coil
acting like the wave formation found inside a waveguide. The peak voltage
points moving toward the ends (sides) and away from the ends (sides) as the
frequency shifts from and toward the ideal dimensional (1/4 wave equivelent)
frequency to an extream point of high voltage point in the center of a coil
(wave guide). This concept would be very sensitive to the earth
electro-static gradient at the moment and elivation of the coil being
tested. As some of us know the earth electro-static gradient varies with
weather and solar changes and are not constant. The varience can be only a
few volts per 10' to tens of volts per 10' depending on atmospheric
conditions and elivation at the moment.
    Please refect on my sight of what you are saying and draw me a visual
consept to see more clearly. At my age I nead pictures. Thank you
  Robert  H 

> From: "Tesla list" <tesla-at-pupman-dot-com>
> Date: Fri, 24 May 2002 22:34:28 -0600
> To: tesla-at-pupman-dot-com
> Subject: RE: Variable Capacitance and Inductance
> Resent-From: tesla-at-pupman-dot-com
> Resent-Date: Fri, 24 May 2002 22:48:11 -0600
> Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
> Hi Dave,
> At 12:40 PM 5/24/2002 -0500, you wrote:
>> I need to interject a comment here.  Despite Matt's insinuation that anybody
>> who takes a sincere interest in Tesla's work worships him as an infallible
>> god, I have found several errors in Tesla's work in my studies.  Apparently
>> I have found another one.  In reviewing Tesla's notes specifically related
>> to measuring the capacitance of a "large structure" on page 282 of his CSN,
>> he states, "The rise in the effective capacity for 47 feet and 6" was ...
>> 26.2%.  Per one hundred feet it would be from this: 55.16% or a little over
>> 1/2% per foot."  It seems Tesla incorrectly remembered the details of his
>> notes and wrote in his article "50 per cent per foot of elevation" when he
>> should have written "50 per cent per one hundred feet of elevation."
>> His CSN correctly state the difference is 1/2% per foot, which is consistent
>> with the rest of his article on variable capacitance.
> Neat!  I don't remember anyone seeing this before!  I hope no one ever goes
> through "my" old notes :o))
>>> He is now saying that the capacitance of the conductive body increases with
>> elevation.
>> While checking his math I discovered Tesla was using the classic formula for
>> inductance instead of a calibrated formula like Wheeler's (which wasn't
>> discovered yet).  Tesla apparently measured his inductances accurately as he
>> noted his measurement was considerably less than the calculated inductance
>> (page 253 CSN.) 
> It would be interesting to do some graphs comparing the formula below and
> Wheelers...  I wonder by what percentage they differed in Tesla's tests.
> For the example in CSN, Tesla had a coil 94 inches long, 99 inches in
> diameter, and 105 turns...
> Tesla came up with 0.029369H
> Wheelers, gives 0.019498H
> Tesla measured 0.02042H
> So the formula Tesla used gives an error of +30.47%, and wheeler's gives an
> error of -4.5%.  If one assumes 106 turns (hard to say if it is 105 or 106)
> then wheelers is only off by -2.76%
> That's why we use wheelers formula  :o))))  I don't mean to be picky, but
> Wheelers formula would have worked just as fine for Tesla as it does for us.
> BTW - Check my math!  I am not known for doing these fast calculations
> right  0;-p
>> Sorry Terry, but Tesla was aware that the EMF affected the
>> inductance of the coil.  He makes such a comment on page 273 of CSN.  He
>> probably was aware of this much sooner, so now I'll need to go back and look
>> for other references.
> Interesting!  He does not say it explicitly but he was so close he
> certainly may have recognized that the uneven currents in the coil were
> affecting his inductances.  But his calculations were too far off to
> pinpoint it.  He studied it a lot but was frustrated.  His experiment on
> page 274 tries to study this but such a method disturbs the coils
> surrounding fields greatly.  He was trying a lot of things, but he just
> didn't have the tools need :-((  The numbers were to course to see the
> effects and quantify them.
>> What's interesting is that Tesla made his correction for EMF from the
>> classic inductance formula values and not from Wheeler's as you and Paul are
>> doing now.  Why don't you try making your adjustment from the classic
>> inductance formula of:
>> 4 pi^2 N^2 R^2
>> L = --------------
>> H
>> Where L is in 1000 inches.
> Because Wheeler's is better ;-)  Just because Tesla used a poor formula is
> no reason we should ;-)  Paul's programs don't use Wheelers but rather the
> finite filament thing like Dr. Rzeszotarski's program MandK.  All the
> modern formula's and computer methods agree to within a percent.  "i" don't
> see a need to base anything off a formula that gave Tesla an answer 30% in
> error.  While the study may be of some interest, it does not "help" things.
>> To put it simply, Tesla was measuring the effect of elevation on a dynamic
>> charged body, not a static charged body.  To see what effect elevation has
>> on a static charged body a capacitor with a vacuum dielectric, (not any
>> other dielectric,) and not connected to the earth, should be measured at
>> various elevations.  A vacuum dielectric would show the most variation due
>> to elevation (distance from influence of the earth,) _if any exists_.
>>>> Thus a circuit vibrates a little slower at an elevation than when at a
>> lower level.
>>> There is a problem here too. Included in my series of measurements are some
>> showing clearly that a *resonator* that is elevated shows a *rise* in its
>> frequency of oscillation. That is what I would expect given that it has
>> moved further away from the ground plane. i.e. - its capacitance to ground
>> has *dropped*.
>> As noted above, raising the terminal increases the amount of dielectric
>> between the sphere and ground, allowing greater potentials on the charged
>> bodies.  Greater potentials mean greater capacitance.  It you check CSN, you
>> will see that Tesla specifically tuned for greatest potential.  To know how
>> this affects your experiments, it would be necessary to understand the
>> tuning method you used.  If you did not tune for maximum potential, then
>> your experiment would not be comparable to Tesla's experiment.
>>> And so it should with the sphere, should it not? Is that not reasonable?
>> Please address this question and show me exactly why my reasoning is in
>> error.
> You say that as you raise the sphere, the capacitance to ground decreases
> and the frequency goes up.  That IS correct according to "me too".  But
> Maxwell knew that in 1873...  I thought we were worried with "unusual"
> capacitance variations that Maxwell's field theory could not explain?
> There is the big factor of the connecting wire which reverses the
> situation, but still no new science there.
>> As I pointed out, you're using static capacitance as a model for a dynamic
>> capacitance.  The amount of extra dielectric that can get between the
>> charged bodies increases.  And this is precisely why the capacitance in
>> variable.  The amount of free flowing dielectric "material" is always in
>> motion.
> In my tests and calculations over the years, the DC, AC, and resonant
> capacitances have all worked out to the same value.
>>> Suppose we had blindly accepted theories that the resonator was a lumped
>> tuned circuit. Where would that have got us?
> Lumped parameter models could be used to accurately predict voltages and
> currents in a Tesla coil.  We all knew it was far more complex and knew we
> were learning to crawl before we could walk.  Today, Paul's TSSP work has
> pretty much shown the real actions but the lumped models are still used by
> at least me with great success in basic design problems.  It got "me" a
> lot!!  Rest assured that my paper:
> http://hot-streamer-dot-com/TeslaCoils/MyPapers/topsync/topsync.html
> Got all the errors pointed out in detail!!  But "they" were right so no
> harm was done.  That paper did launch some great work to follow!!  So just
> another stair step...  I think it's most important contribution in the long
> run was to show that hard data could finally be made available to all.
> Even if "I" was wrong, the data was suddenly there in plain sight for all
> to see and interpret themselves.  Today those graphs looks old and obvious,
> that was not the case in 1998!  The lumped models can still do a few tricks
> TSSP can't.  However, I see Paul is starting to use my 220k + 1pF streamer
> model and wishes to improve on it.  If TSSP can do as much for streamer
> modeling as it has for secondary modeling, the lumped parameter model will
> be left in the dust of history!!  Of course, history suggest that someone
> will come along still and...
>> I hope research was done before blindly knocking the guys who came up with
>> the lumped tuned circuit?  If it wasn't, I'll bet there was a mud slinging
>> contest over that.
> There was :-)))
> "#*-at-&%!! . . . Thor, you dumdum! You CAN't use lumped circuit modeling! .
. ."
> http://www.ttr-dot-com/corum/index.htm
> I did, and it worked just fine....
>>> Suppose we had accepted theories that the resonator could be modelled as a
>> uniform transmission line. Where would that have got us?
> It was a major stepping stone to the lumped models that were a stepping
> stone to the TSSP models...  It's all a long chain of people trying to
> prove the last guy wrong :o))
>> I hope research was done before blindly attacking the guys who came up with
>> that theory, too.  What could blind mud slinging accomplish?  Ultimately all
>> these mud slinging contests are ended with hard core research.  So why not
>> do the research first and avoid the mud slinging?
> We like a good fight :o)))  And it makes winning sweeter ;-))  However,
> watch your back since every champion has a challenger...
> Of course, the "mud slingers" or not lightweights and they know a heck of a
> lot!!  Their punches hit hard and a "new theory" had better be solid as a
> rock or it's gonna get carried out on a stretcher!!  However, when a solid
> theory does come along, it knocks them off like flies...
> The problem with the thread here is we have an idea that has no data to
> back it up.  It was Tesla's idea so we all respect it but...  We don't see
> the data...  Tesla tells of it but his calculations are not "good enough"
> by today's standards.  The more we look the more holes we find.  Also,
> other modern tests that "should" show such unusual things do not.  We just
> don't have that "line in the sand" bit of evidence that challenges us to
> explain.  If we ALL could take a sphere and measure 20pF tonight and 50pF
> tomorrow, things would explode like wild fire as we rushed to find out
> why!!!  But the sphere is 20pF tomorrow too, so we just yawn and go back to
> sleep.
> The paper of mine above came at a time when many people were sure the
> currents between the top and bottom of the coil were 90 degrees out of
> phase.  Having some guy claim (rather loudly) that they were in phase and
> then provide nice scope pictures of them in phase was a "big problem" with
> the status quo.  It could not be ignored.  I happily answered any question
> as to the setup and helped others to reproduce the results and make fiber
> probes so they could do such work too.  Rest assured, people searched for
> the error in the data but they didn't find one.  However, they did find a
> "few" errors in some of my conclusions ;-)  Lumped models followed that in
> short order that also demonstrated that "it worked" and they put the direct
> challenge "if it is not right, where is the error".  Those models are just
> a valid today as they were then and they easily defended themselves against
> the challenges of the Corum's paper above.  Of course, time marches on and
> far far better models are now coming up.  If a new model works, it gain
> acceptance easily.  "Too" easily as I and now Paul find.  Paul asks again
> and again for challenges or peer review to find errors in TSSP, but no one
> wants to challenge the champ when he's at his best!!  However, if an error
> were to pop up, they will be on us like tigers!!
> Getting back to the matter at hand...
> We cannot trust Tesla's original data for sphere elevation vs. capacitance
> in the Colorado Springs notes.  There are too many unknowns and unaccounted
> for sources for error.  Whatever conclusion we would make from that data,
> could be shot full of holes far far too easily.  Previous posts to this
> thread mention many of them and they cannot be defended against.  The
> tables like on pages 209/210 would evoke wild laughter from the audience as
> they carried our beaten carcasses out :o))
> However, we are not "defenseless" ;-))  Programs like E-Tesla6, TSSP's
> Tcap, and the new fastTesla can meet the challenge of finding a 30 inch
> sphere's capacitance at various elevations.  The testing of that computed
> data can be compared to real modern measurements easily enough:
> http://hot-streamer-dot-com/temp/P5240023.jpg
> But there is one question.  What on Earth will we find that is "unusual"?
> Although "I" have never done "this" exact test, all the testing I have ever
> done suggest that we will see nothing unexpected in either the computer
> models or the actual tests.  We will see how well the models correlate to
> actual results but I think we will simply discover we are wasting time
> proving the obvious.  Tesla's "astonishing phenomenon" is simple physics
> and electrostatics:
> ""Continuing the investigation of this astonishing phenomenon I observed
> that the capacity varied with the elevation of the conducting surface above
> the ground, and I soon ascertained the law of this variation. The capacity
> increased as the conducting surface was elevated, in open space, from
> one-half to three-quarters of 1 per cent per foot of elevation.""
> Of course, the reason the capacity "increased" is because of the connecting
> wire and such.  Tesla just did not see or have the tools to see what was
> going on at that time.  Today, it seems obvious...  Could weather and all
> kinds of other things have affected his original experiment?  Obviously,
> yes!!  We could eliminate those effects, at least on the computer, and then
> pat ourselves on the back for proving nothing...
> To make a long story short, what on Earth could be proven or what advance
> will this type of testing give us?  If it was easy, we could just do it for
> fun.  But there is a full day's work there at least.  There are far greater
> fights to be fought...  Measuring the top terminal voltage of a Tesla coil
> (directly) is the big challenge of the day.  Never been done...  Big
> payoff...  Big challenge...  ;-))
> Cheers,
> Terry