TinselKoala's Magnetics Workbench

[0c]

TK,

Thanks for the many nice presentations you have put together. I wondered whether you would take the time to explain and illustrate another electromagnetic device -- purely for educational purposes.

What are the magnetic characteristics of a Tesla Bifilar Coil: location, shape, intensity, and polarity of magnetic field. And how does it compare to or differ from a standard spiral wound pancake coil with the same number of turns?

If you would take the time to answer this question, I have some related ones to ask as well.

Thanks,
0c

(Maybe someone can collect some references to TKs other materials here?)

[ramset]

Sir  This is a confusing thread you have opened
Are you fishing or is TK a buddy of yours?
   Chet

[0c]

I was hoping we could gather references to the TinselKoala photos and demonstrations into a common location that would be easy to find and reference, instead of searching through all the threads to find them. There's a lot of good educational materials there.

I also had a question that I would love to have addressed in the same fashion TK has done in the past. If you can provide the info and illustrate the magnetic similarities and differences I asked for above, go ahead. But I like the way TK does what he does. He gets the ideas across very well.

Buddies I don't know, but would be proud to make that claim if it was true.

[TinselKoala]

Hmmm...thanks for the flowers...
I wish I could answer the question properly "off the top of my head" but I can't. As you know, there are a lot of variables to consider.
The term "bifilar" has been used to describe many other types of coils but I think you are referring to Tesla's flat bifilars as described in 512340. In general when compared to a flat spiral coil of the same diameter and number of turns, the interturn capacitance (which we often ironically seek to minimize) is much greater in the bifilar series-connected form. This capacitance can store a lot of charge, and when such a coil is operated in resonance, some people believe this capacitance can interact with the coil's inductive reactance in interesting ways.
I have a small TC that is set up to use different primaries. It might be possible to try a pancake series bifilar primary on that coil to do some comparisons. I'll see if I can dig it out and dust it off. A cylindrical parallel bifilar secondary that I wound for that coil didn't work out so well--not enough insulation between windings, so they just acted like a single winding. Next one will be flat and vacuum-potted in wax or epoxy.
There are other so-called bifilar forms of winding too. Some are non-inductive loops, some are just multiple windings on the same core. I even know less about these.
I'm not sure what you intend by this thread; I'm flattered by the attention, but I'm really not trying to make a big fuss. I've put some videos up on YT and those can be easily found, and I've also linked to some longer larger files on mediafire.com.  Anyway, thanks for the comments.

[0c]

TK,

Thanks for the quick response. The Tesla patent you referred to is the one I'm interested in.

I'm mostly interested in the magnetic field characteristics of the coil as a DC or pulsed DC electromagnet, not in AC resonance. I have heard the Tesla bifilar coils have a significantly greater magnetic field. How does it compare under these conditions to a similarly sized spiral pancake coil, or to a solenoid? How is the field distributed across the surface and center of the coil? What difference does an iron core make, does it help concentrate the field in the center?

I have other questions as well, but they will based on what I learn from these initial questions.

Thanks again,
0c