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Re: Current distribution in resonators



Hi Duane

At 02:23 PM 04/19/2000 -0600, you wrote:
>Hi All,
>
>In the photos referenced below I am showing the results of experiments I
>have performed to show the average current in different parts of the
>resonator. These experiments are very simple and give a good visual affect
>of what the standing wave looks like. I think Terry has been doing some
>very nice work with optically coupled current sensors (correct me if I'm
>wrong Terry), which may give better information than judging the brightness
>of a lamp. The lamp experiment gives a very good feel as to what is going
>on though, especially if they are viewed real time while the frequency is
>changed a bit.

I built a secondary many years ago with tri-color dual LEDs all along it
after seeing this described in your book.  I had much fun with that toy but
it fell into bad disrepair and I no longer have it. :-(

>
>The first photo shows 11 incandescent lamps placed along the resonator to
>show the average current at that particular spot.
>
>http://www.aros-dot-net/~gbyrd/tesla/lamps.jpg
>
>For some funny reason the lamp at the bottom of the resonator does not look
>as bright as the lamps just above it? 

Interesting...


>The lamps are a type 7387, 28 volts -at-
>40 ma. A lamp is non-linear, so current value is hard to judge just by
>looking at brightness. Even with the lamp experiment, I can't help thinking
>it resonates exactly as a lumped circuit. The TOTAL energy is continually
>changing from capacitive energy into inductive energy, and vice verse,
>every 1/4 cycle. The LED experimant can be seen here:
>
>http://www.aros-dot-net/~gbyrd/tesla/leds.jpg
>
>The LED experiment is quite interesting. Even with no top load, except a
>small screw, the LED at the very top of the coil is glowing some! 

One might think that the last winding would have no current but that last
winding and the terminal connection are responsible for charging the entire
space above the coil!  The current needed for that is actually fairly
substantial.

>The LED's
>indicate the current (standing wave) is alsmost linear. Lumped circuit? For
>all practical purposes, YES! A lumped component like a capacitor, when
>combined with an inductor, can cause a reflection property similar to a
>reflection from an open circuit in a transmission line.

Indeed, that's why were are trying to find situations were the difference
between a lumped and T-line is profound and easy to measure.

>
>The ratio of length to diameter in this coil is close to 1:1. I think if
>the highth is much greater than the diameter, the theoretical 1/4 sine wave
>shape suggested by transmission line theory may start to show.
>

This is what Antonio has suggested.  A very long skinny secondary may look
more like a T-line but the Z-axis (non-TEM) affects still seem very profound...

Cheers,

	Terry


>Have fun, Duane
>