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Re: Secondary Resonance LC and Harmonics.



Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Chris,

At 11:34 AM 6/25/2005, you wrote:
Hi All,

I've just wound my first secondary, and in my eagerness I ignored most guidance and just wound as many turns as possible on a piece of 3.5' x 4" tubing. It turned out to be approximately 2K turns (gulp).

Probably ok ;-)


I managed to get my hands on a nice stainless steel sphere, which sits nicely on top. I was just 'playing' with my scope and signal generator, when I discovered that when I set the sig gen to oscillate at 76KHz or 416KHz I don't need to connect it to the coil in order to show the signal on my scope, I only need to touch the probe and the signal magically gets on to the coil and scope!

Yes, this is how folks with test equipment can check the resonant frequency. Us about a 2 foot piece of wire. The "official" antenna is described here:


http://hot-streamer.com/TeslaCoils/MyPapers/planant/waveant3.html

It provides a flat frequency response, but just a piece of wire works good in many cases.

- I'm guessing that my coil and top sphere are acting as a tuned LC tank circuit, with a resonant frequency of 76KHz and a harmonic of 416KHz. Either side of these frequencies the signal drops off.

Yes! The one that gives the strongest signal (also lowest frequency) is the main or fundamental. There are higher harmonics too.


Paul has an extensive site on this:

http://www.abelian.demon.co.uk/tssp/


Does this make sense? Has anyone else experienced something like this? How *badly* tuned is my coil? Should I take some turns off it (not yet varnished)?

It depends on if you can tune the primary circuit to match that frequency. It seems pretty low... Might want to check with one of the many Tesla programs out there to be sure. If your primary system will not tune to the same frequency, it is "bad"...


Cheers,

        Terry



Thanks

Chris