The bifilar pancake coil at its resonant frequency

[Grumage]

Grum, thank you for muddying the waters again. Perhaps you would take another look,
this time with your glasses on.

Start anywhere, follow the wire around the coil and see where you end up.

Perhaps I should have taken these off ?   

You're quite correct, the photo does get a little blurry just before my yellow line.

Cheers from a rather embarrassed Grum.

[MileHigh]

Dear MileHigh.

Whilst I agree with your sentiments, there must have been " some " reason for Tesla to have built a coil of that size. Does anyone know ?

Cheers Graham.

I am no expert on Tesla's life but from what I can remember from watching a few documentaries, at certain points in his life he lost his benefactors or his employers and he fell on hard times.  He needed to generate renewed interest in what he was doing to make himself more marketable.  So I think that's the main reason for things like the various staged photographs.  There is the famous time exposure picture with all of the big electric arcs for example.  So that big pancake coil may have been used for experimenting initially and then afterwards as a prop for some publicity photographs.

Is there any writing by Tesla about that big pancake coil?  To go full circle, it's just a coil.

I think the greatest thing he did was the Niagara Falls power dam project and all the associated technology and equipment to bring AC mains power from the dam all the way to the consumer.  It's not really rocket science but somebody had to do it first and that man was Tesla.  It's comparable to the invention of the steam engine.

MileHigh

[shylo]

Well I don't think there is anybody trying to mis-inform , I do have a question.
Take a single coil, pass a single magnet over the coil, a flow is created in one direction,upon approach of the magnet, but as soon as the approaching magnet begins to induce that flow, an opposite flow begins, right?
But this reverse flow is not as strong as the flow that is being induced,so it can't be used to create an inducing  flow of the same strength, right?
But what I'm trying to do is take 2 of the reverse fields add them together so they are stronger than the initial.
You need to use more than just one machine to be able to do this,but it is still a catch 22 because you use 2 to make one.
I should say the coils are loaded at all times.
artv

[evostars]

I made a new topic describing some of my experiments.
http://overunity.com/17222/some-bifilar-coil-experiments/msg503913/#msg503913

[TinselKoala]

MH: Right you are, as often. Another thing that is not often appreciated by the modern experimenter is that in Tesla's day, back at the beginning of radio, frequencies of 1MHz or more were practically unknown. You can see Tesla's words in many places where he speaks rather in awe of "one million, or millions, of pulsations per second!" Yet today these frequencies of 1-10 MHz are supplied by even the cheapest hobbyist function generators without much difficulty. Hand in hand with frequency is the rise and fall time of "pulsations". Tesla would have been in hog heaven if he could have attained rise/fall times in the single-digit nanosecond range, and he spent lots of his creative juice on spark gap designs specifically to minimize rise/fall times. Yet today we play around with single-digit rise/fall times even on the amateur's bench.

Grum: No problemo, mi amigo! It's hard to decontstruct stuff from ancient photos that were likely published first in half-tone dots in some newspaper of the time.
I'm waiting for someone to argue that there are two wires bundled together in that thick tarred-cotton-wrap insulation.  Could be, but I don't think so, since there is no evidence of the "crossover" connection that has to be there for a TBF winding.  Does anyone  know the date of that photo? Perhaps the coil was made before the invention in #512340 was filed. Why a big coil in the vertical plane? Maybe it was upended as a photo-op. Just speculating.

Shylo: Not current, but EMF, that is, voltage.
-E=d(B)/dt .... Faraday's Law of induction and Lenz's Law (the minus sign)... meditate upon that until you can grok the fullness of it.