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Re: Non-Linear Coil Winding Experiment. (and more tests!)
---------- Forwarded message ----------
Date: Mon, 13 Oct 1997 21:26:31 -0600
From: terryf-at-verinet-dot-com
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Non-Linear Coil Winding Experiment. (and more tests!)
>Subject: Re: Non-Linear Coil Winding Experiment.
>
>Hello All,
Terry said in part:
>> I have been experimenting with different types of coil windings.
><snip>
>>The results are as follows:
>>
>>Coil #1
>> F0 = 1597.6 kHz
>> Inductance = 2.07 mH
>> Self Capacitance = 4.79 pF
>>
>>Coil #2
>> F0 = 1815.7 kHz
>> Inductance = 2.16 mH
>> Self Capacitance = 3.56 pF
>>
>>Coil #3
>> F0 = 1829.0 kHz
>> Inductance = 2.31 mH
>> Self Capacitance = 3.28 pF
>>
Then Mark said..
> I would have expected distributed (self) capacitance to be nearly
>constant, if the winding length is fixed at 10 inches. Are you sure your
>measurement method is not affecting F0? (I learned this the hard way
>recently.) How did you measure/estimate Cdis?
>Regards,
>Mark S. Rzeszotarski, Ph.D.
>
>
Mark,
Cself was calculated from the measured inductance and the resonant
frequency C = ((1/(2 * PI * Fo))^2) / L .
I checked the test equipment with some older coils which I know well
and everything checks fine. The oscilloscope has the standard 10:1 probe
(100MHz) into a 40MHZ dual-trace scope. The inductance was measured with a
hand held LCR meter that I use often and trust. The frequency was measured
with a 100Mhz frequency counter. The coils were driven from a sine wave
generator with a 600 ohm output Z. I also ran the coils with a 50 ohm
square wave generator that can drive much harder but the results were the
same. All the equipment is less than five years old and seems to work
flawlessly.
I tested the coils in a reasonably open space on a hardwood floor 6
inches above bare dirt. I tried the coils in other locations at various
distances from the surroundings the results don't change significantly
unless I get within about 2 feet from something big. As far as I can tell,
everything is reasonably accurate. The field mapping experiment obviously
had some variability but the general results I feel are accurate.
One thing that blew one of my pet theories to hell is that the
quarter wavelength for a 235.6 foot long wire is 1043.7 kHz. All these
coils exceeded that frequency considerably (so much for worrying about wire
length vs frequency). I tried very hard to find a lower resonant frequency
but it simply wasn't there. The fields around the coils were consistent
with a quarter wave resonance so I am sure I didn't hit an off harmonic. It
took me awhile to find it up at 1.6 MHz. All the coils were tested one
after the other with no change to the test setup.
I feel that the reduction in the self capacitance was due more to
the field concentration in the #2 and #3 coils rather than the winding to
winding capacitance. There is probably some mathematically perfect way to
wind these coils other than the formulas I used. Any suggestions??
Just for fun, I turned all three coils upside down and retested the
resonant frequency. As I expected the results for coils #2 and #3 changed
drastically. They are:
Coil #1 upside down
F0 = 1606.0 kHz (1597.6 kHz right side up). This coil is not
perfectly centered on the coil form.
Coil #2 upside down
F0 = 1390.5 kHz (1815.7 kHz right side up).
Coil #3 upside down
F0 = 1257.8 kHz (1829.0 kHz right side up).
I haven't had a chance to look at the field distribution with the coils
upside down yet but it should be interesting. I snapped a bunch of pictures
of all this which I will post once they are developed and I remember how to
set up a web page again.
Also, DR. RESONANCE Wrote..........
>To: Terry
>
>Sounds like an interesting experiment -- have you applied power to all
>three yet to determine performance under actual operating conditions??
>That report would also be interesting especially if you "pushed" each to
>near breakdown performance.
>
>DR.RESONANCE-at-next-wave-dot-net
These coils were never intended to be used. They may burn up do to
their small size and light construction. They were intended as a way to
easily examine the subject of non-linear winding. The results were also
needed to estimate the frequency of full sized coils to try to match the
primary equipment I have (Fo at 1.8 MHz is high!). With such varied results
between these coils the perfomance of full size coils will be hard to
compare. This will need more thought!!
If anyone with good equipment would like to examine these coils and
verify my tests, these coils are small and light so I can mail them. The
only "ounce of blood" required is that you would need to report your results
to the group and possibly forward the coils to anyone else who would like to
see them. I invested about $4.00 in these coils so the trip can be one way.
They would need a little coat of Krylon to keep the windings in place but
that shouldn't hurt them. E-mail me if interested. I don't need any more
coils around the house :-)).
Terry