@chet
Thanks for the thanks, I´ve only ever built a small transistor driven tesla coil quite a few years back, very small sparks, but the tuning and method of operation is just the same as the biggies.

@all,

OK, I´ve just realised what "tuning for magnetic resonance" might mean with regard to a Tesla coil...

Most all coil builders will tune for maximum antinode at the top, quarter wavelength, three quarter etc. This will give you the best sparks and streamers from the top load, that´s what coilers tend to go after, they like the sparks, don´t we all!

BUT.... If you tune for node at the top and node at the bottom, half wavelength, full wavelength etc. Then the coil will appear to be a dud, no electrical discharge from the end. BUT it will have maximum mag field output at the antinode/s in the middle of the coil.

So you would then have your secondary sitting there doing nothing spectacular, no sparks from the top, nothing. However the middle of the coil will be emmiting a fairly intense oscillating magnetic field,  not electric. The coil could then be said to be tuned for magnetic resonance.

The neon bulb method I mention above is best for tuning this way, just get max brightness in the middle and no light at the ends. You´re then tuned to half wave of the primary frequency.

OK, so we now have a secondary just sitting there quietly, provided the insulation is good enough on the wire there will be no sparks anywhere. It might also be a good idea to short the secondary coil ends together. To convert any remaining electric potential to a little more mag field output.

To extract power from this one could use a third innermost winding within the secondary or perhaps some capacitive coupling to the antinode? Or maybe, just maybe, it could be reflected power back into the primary which would make sense as his primary is in the middle of the secondary coil!?!?

note: If the secondary is shorted the whole thing starts to smell of Thanes Perepetia, just a solid state version.

Yucca
NICE This is a very interesting idea/concept for tuning to magnetic resonance
And yes the shorting part very Crankypants esk

Yucca I received this before any of your posts

I received a PM[solicited]from another experimenter that I know has done VAST research in this field and feels this is very promising [up to his ears in another project several]
But he said I could share this here
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Well in any case many things are getting mixed up here.
Tesla was always about accelerating the electric field because this field can go beyond C, lightspeed.
In typical Tesla setups you will find there is only about 20% magnetic coupling between his primary and his first secondary coil.
This gives rise to what is called the dielectric current which moves at high speed over the windings.
If you look into the works of Eric Dollard you will come to the final conclusion that the Tesla coil as we know it, is an unfinished device.
It is just a toy to produce sparks.
The real Tesla coils have a set of five coils and it is called a balanced coil system, meaning there is as much displacement on the positive side as there is displacement on the negative side.
The classic Tesla coil as we know it has only two coils and thus it only plays in one region of either the negative or the positive side of the story, and it was not the way Tesla ment it to be.

Tesla was pulsing the earth connection at the exact resonance frequency of the earth itself, the wardenclyffe tower was just a weight to push up against, something he could put his back on to be able to push into the earth.
So the tower unlike what many think, wasn't transmitting ,it was just the anti weight, and that is most important in balanced setups.

The magnetic field however cannot go that fast.
When the magnetic field reaches C, lightspeed, it gives birth to what we call radiowaves, and the energy is radiated away as radiowaves.
This is how our radio's recieve their channels.

That is a whole diffrent story compared to what Tesla was about.
In radio fields the local field strength is huge, where Tesla was using the earth as a one wire conductor without any radiation at all..

It is similar as if you blow up a baloon, the pressure is felt everywhere around the baloon, this represents the earth and Tesla was building recievers that would respond to that pressure.
Offcource you can see now why it is so important to have a critical anti weight, because if there isn't any, it would just go up and down with the pressure and you cannot tap into it.

So the main thing here is that you will always need an anti weight in order to interact with the source.

2 fantastic posts Yucca.

food for thought....and more than that, a very simple experiment for tuning my coil differently.  I didnt know i could tune it to half wavelength and it would appear dud.  I'm definitely in the ''Mostly all coil builders'' category.     Several neon bulbs have now made there way onto my shopping list for tomorrows trip to the radio market.  Very interesting to hear your ideas about what magnetic resonance might mean.....with any luck i'll have the beast magnetically resonating by tomorrow.  I've got my camera back now, so i can make some vids.  Thanks for all your ideas and help!


I'm wondering what happens if you tune it like this, and then try wireless transmission with a receiving coil.  Will it work?  what do you think?

I have a similar project but I want to use an automobile alternator as the primary and a triple secondary in a Y configuration. I don't want the sparks but something like what Yucca described two or three posts above. Any ideas will be greatly appreciated.

Thank you for all the info!