Re: Quarter Wavelength Frequency

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net> 

(Second attempt, first one bounced)

Hi Jared,

Ive been following this thread with much interest.  There are a lot of
experience folks on this list that have said that 1/4 wave resonance does
not come into play  and the resonance is determined by the effective LC
parameters of the coil (or coil and top load combo).  L being a little
stange here because the current profile is not linear.  One argument that
I've heard often is that the individual turns of the coil are mutually
coupled to each other and thus a field couples other turns directly and
sorta bypasses the conduction path following the wire (if I may over
simplify this).

There have been other discussons about being out of tune and resulting in
voltage gradients that have caused racing arcs in portions of the coil.  To
me this has some sort of wave action feel to it, not totally unlike voltage
rises in a transmission line that is not properly terminated.

If I understand what you have said, would it be the case that if one excited
a coil (assume no top load) at the base to find its resonances, one would
find two resonances - one determined by the wire length and the other
determined by the effective LC parameters of the coil?  If this is true
would the same be the case with a typical topload present?

Gerry R


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, July 09, 2004 7:35 AM
Subject: Re: Quarter Wavelength Frequency


 > Original poster: Jared E Dwarshuis <jdwarshui-at-emich.edu>
 >
 > Mr. Nicholson: Yes we believe that an envelope exists between L.C.
 > resonance and wire length resonance. When we run our full wave devices
 > we can only get them to work at the wire length frequency (or
 > multiples). Changes in top end capacitance do not destroy the
 > resonance; it appears to be fixed by the primary L.C. and the wire
 > length of the secondary.
 >
 > Observing and understanding are different animals.  We suspect that
 > L.C. resonance requires an interplay of timed events between both the
 > inductor and the capacitor, where wire length resonance deals with
 > timed events along just the inductors length itself.
 >
 > When we ran up the Levi configuration for the first time we got a slow
 > beat frequency between the two coils (a slow cycling of spark length).
 > We knew the wire length difference was very small, so we removed wire a
 > bit at a time from one of the coils and the beat frequency got slower
 > and slower.  When we had removed about a meter of wire, the beat
 > frequency disappeared entirely.  Now, subtracting a wind or two of wire
 > from an inductor with most of a mile of wire on it is a negligible
 > change in inductance.  And, on the surface it also seems to be a
 > negligible difference in wire length.  But this difference in wire
 > length was enough to eliminate the beat frequency.  Making two wires
 > nearly a mile long to almost exactly the same length is not too
 > difficult.  But, making two toroidal inductors by hand at different
 > times and of different gauge core material to exactly the same
 > inductance is very difficult (read impossible).  It is not possible
 > that removing two winds from one of the coils would match the
 > inductance that closely.
 >
 > Yes the velocity appears to be very close to, if not exactly, the speed
 > of light. How close? couldn?t say. We have to base our conclusions
 > mainly on observations and calculations. Our instruments are only good
 > for two digits, so we have to look at a body of evidence to draw
 > conclusions. Naturally, all of our work needs confirmation,
 > re-examination and possible re-working by people with different skill
 > sets and interpretations than our own.
 >
 > Mr. Watts I believe my choice of wording may have offended, and I
 > apologize. And add that we both have an enormous respect for the small
 > minority of coilers ( maybe a dozen or two active theoretical
 > experimenters ) such as yourself who have shown a keen interest in
 > understanding and developing theory.
 >
 > I believe you were referring indirectly to our ideal resonance
 > formulae, There?s not much to this formulae, it is merely an extension
 > of already existing formulae to a general case.   ( a convenient
 > accounting tool) It is Ideal in the same sense that the classic
 > inductance formulae was ideal, it assumes a uniform magnetic field
 > throughout. Our formula also pre supposes that periodicity occurs at
 > quarter wave intervals, that inductance for purposes of establishing
 > resonance can be found within these intervals. This formulae
 > specifically states that it is only applicable to wire length
 > resonators.
 >
 >   We use Wheelers formula for all of our primaries, for short inductors
 > it cannot be beat, but when we go to make a secondary we use the
 > altered classic form for inductance. The two formulae differ
 > significantly in the values they predict,  but they are both correct
 > for the applications intended.
 >
 > Mr. Epp:  Suppose we make a hypothetical secondary with 1000 turns of
 > 22 gauge around an 8 inch diameter pipe, Medhurst predicts about 11.7
 > Pf.  Wheelers formula gives .523 Henry while the classic inductance
 > formula gives .594 Henry, then the self resonant frequency of this coil
 > would be between 240,000 and 260,000 Hz
 > But the predicted quarter wave wire length frequency is only 118,000
 > Hz. The coil operating at 118,000 Hz will have much larger amplitudes
 > and be easier to tune.
 >
 > As to the differences between a quarter wave, a half wave, and a full
 > wave. To simplify I will only consider the case where they are all wire
 > length dependent.
 >
 > So I make the coil described above and resonate it at 118,000 Hz.
 > After a while, I get bored and decide I want to make a half wave.  Here
 > is what to do: make an extra coil exactly the same, remove the old
 > ground and solder the two coils together. Slap the same primary on as
 > before, centering it between the two coils. Remove the top end
 > capacitor and replace it with a capacitor that has ? of the capacitance
 > and stick another ? capacitor on the other end of the coil. Now you
 > have a half wave, but you can run it with one breakout or two.  It
 > looks like a quarter wave with just one breakout as the entire arc will
 > appear on the end with the breaker (assuming your radius is large
 > enough to suppress an arc without a breakout).  If you put the caps
 > close together you get a nice clean arc between them. Now mind you we
 > could also make a grounded half wave, but there would be no advantage.
 >
 >     So I get bored again and I want a ? wave; no problem.  Make another
 > coil, stack it on top, put the quarter wave capacitor back on top.  Put
 > the primary on the bottom and ground it like a quarter wave.
 >
 > This time I want a full wave.  We have some choice here. We could place
 > 4 inductors in line and ground both ends then place the ? capacitors at
 > the ? and ? points.  We could also assemble a pair of ? waves,
 > described above, and drive just one of the pair and get a capacitor
 > coupled anti- symmetric mode arrangement (Marsha configuration).   We
 > can arrange one breakout or two between the coils.  Amazingly, we can
 > even take two Saskia coils, power just one of the coils, place just one
 > ? capacitor on each coil and we will have satisfied the capacitance
 > requirements (Levi configuration). But you can see this is very much
 > like 8 quarter waves ( two sets of 4 quarter waves driven anti-
 > symmetric), where we drive just one pair and the rest go along for the
 > ride.
 >
 > The role of Medhurst is not a cumulative one.  We calculated it, once
 > and only once, for a quarter-wave section, as it also follows the
 > trends of periodicity.
 >
 > All of this is like rope resonance.  Once you find the driving
 > frequency and tension to get one anti-node (the bump part) you can
 > simply add more sections of the same length rope and get more
 > anti-nodes.  You don?t change the frequency, and you don?t change the
 > tension.                                                      ( see our
 > derivation of correspondence)
 >
 > Good luck and don?t get hurt.
 >
 >