Tesla's "COIL FOR ELECTRO-MAGNETS".

[Magluvin]

Really Magluvin?

I am going to quote you:

Everything I highlighted above in your statements is completely wrong.  Tesla was talking AC impedance in a series LC resonator going to zero - that's the "neutralizing of self-inductance."  So you started this thread with a completely incorrect impression of what this concept was all about and you made statements about basic electronics that don't make sense.  And I will repeat again that none of what Tesla stated in the patent had anything to do with pulse motors and you are incorrectly applying it to pulse motors.

First line is mine and the second line is yours:

Honestly I think you actually were stymied and weren't able to answer the question after reading the ongoing discussion so you threw it back at me as an attempted diversion.

Quoting you again:

From your comments further above, it's crystal clear that you are the one that didn't understand what the statement meant.

Nice try at being the "cool dude with the poker face," but I ain't buying it.  Better luck next time.

Really?  Let's hear you explain where I am wrong then.  Please no throw-backs or ducking the question.  Why should I have to hit the books with respect to my statement?

MileHigh

"First line is mine and the second line is yours:

Honestly I think you actually were stymied and weren't able to answer the question after reading the ongoing discussion so you threw it back at me as an attempted diversion."

Twist it any way you want. I was just tired of explaining it to you. I explained it before the first quote block in your post and the block shows that. But you didnt copy those quotes did ya. Sly old dog you.

I do see one mistake in my first block you quoted where I say the cap and coil get dc connected across and the cap charges instantly but the coil does not. After 'not' I should have wrote 'but the coil does not charge instantly' I can see how that might not have been well taken.

It was an example I used to get you to understand the difference between the coil of an LC and the 'coil' of the bifi. If we applied dc and watched closely, the lc 'coil' will not take on the initial current from the dc, the cap would. But the bifi, the cap is in the coil. How does that capacitance charge in the coil? Through the windings, thats how. So the bifi coil does take on initial currents, unlike the standard coil of an LC. But you still wont get what Im saying.


"Really?  Let's hear you explain where I am wrong then.  Please no throw-backs or ducking the question.  Why should I have to hit the books with respect to my statement?"

Well there Im refering to you mentioning that all coils are just standard coils no matter how you wind them. Even TK does not agree with that but you still just keep on keepin on. And the other reason is you have used the excuse that you have been out of actually working with this stuff for 30 years and its your reason for when someone finds you wrong and you cant dig yourself out of it. Like the LEDs that work at 1.2v. Remember that one and what you said when I corrected you that its near minimum 2v for an led to conduct, red ones especially, other colors all the way above 4v before conducting. But you blamed it on "Its been 30years, so I made a mistake."  Well then, even I have trouble remembering every detail of things from that long back. But I keep on keepin on with a lot of things, to keep it fresh and whats new.

So your flagrant tossing of facts that are not true about coils and their various windings and functions needs to be revised.  Books, web, its all there.

I understand that Tesla used the word 'frequency' which does signify AC not DC. But then we also have to look at the title of the patent. 'Electro-magnet'   I have never seen Tesla refer to any of the coils in his HV devices or transmitters/receivers as 'Electro-magnets'.  Nope.

What is your definition of an electro-magnet?  And if you were to use an electro-magnet, by your definition, would you us DC or AC?

I did a lot of experiments on a coffee table for a while, and on my dresser, for a while. It doesnt take much to actually do some experiments like these, you do know?

Mags

[forest]

Hmm...so Tesla had a LC tank circuit without capacitor , very clever. My question : what kind of LC circuit it is ? Series or parallel ? Or maybe it depends how you connect things together ?    I surely know that the secret of effective device is to match two resonances....   I think Tesla knew very well about that except LC resonance there is also longitudinal standing wave resonance. I saw once in Colorado Notes cryptic statement about adjusting primary for resonance and how it's hard to do it obviously (because we cannot find the best match for all parameters here.

[MileHigh]

Magluvin:

"Really?  Let's hear you explain where I am wrong then.  Please no throw-backs or ducking the question.  Why should I have to hit the books with respect to my statement?"

You didn't even try to answer the question, you ducked it.  It's a technical question and it calls for a technical answer and you apparently can't do it.

I'm not even going to bother with the rest of it.  People can read the thread and decide for themselves.  The basic point is to not have the misconception that so-called "series bifilar" coils have some imagined advantages when it comes to making a pulse motor, whether it be as drive coils or as pick-up coils.  You want to not have beginners spend months or more with this false notion.  The worst case scenario is it becomes another "power comes up from the ground" misconception that takes on a life of it's own.  The minuscule capacitance in a series bifilar coil will not affect the operation of a typical pulse motor.  You look at the situation and analyze it rationally and arrive at a logical conclusion.  No need for fantasy hunches that you want to assume are correct until proven otherwise.  No relation to the Tesla patent at all, perhaps the "worst" fantasy.

You remember the RomeroUK pulse motor I am sure.  There were nine pick-up coils and eight rotor magnets.  All of a sudden people starting saying, "Woooo!  There is a 'magical' counter-swirling magnetic interaction because of the 8/9 ratio that travels around the rotor in the opposite direction of the rotation!  Maybe that's the secret to the over unity in the RomeroUK motor!!!"

That's the kind of nonsense that you want to avoid happening with series bifilar coils in a pulse motor.  In this application there is essentially no difference from ordinary coils and it's important to debate that so newbies can hopefully learn and decide for themselves.

And I have tons of more effective bench experience than you and I really don't learn anything of substance from you, just to make that clear.  You are just trying to put on a brave face.

I have made my technical points and hopefully that will help some experimenters and prevent them from wasting time chasing dead ends.  That's a good thing.

MileHigh

[TinselKoala]

Gah. Everybody's right, and everybody is talking past each other.
1. Farmhand is right about Tesla's patent.
2. Tesla was right about HIS design of bifilar spiral coils operating at high voltages with low self-inductance--- low enough to be effectively "cancelled" by the inter-turn capacitance of a _carefully built_ spiral coil with the series-bifilar hookup. I've already said why he wanted these characteristics. Obviously if the increased capacitive reactance of a bifilar coil is to cancel the inductive reactance (not the inductance) then that inductance must be fairly small to begin with, meaning short wire length (relatively), non-saturable core of low permeability (like air) and high voltage difference between adjacent turns.
3. MileHigh is right when he says there isn't a _fundamental_ difference in coil winding techniques _in general_. Tesla's patent and the phenomenon he describes are important in a very specific design case: High potential difference between closely-spaced windings in a specific design of coil. He also used this same concept of increased capacitance in later work with his "disruptive discharge apparatus" which uses a specially-constructed secondary coil and pulsed DC stimulation.
4. Magluvin is right about there being differences in behaviour--- but these are second-order effects. Take two equal lengths of wire and two identical iron rod cores. Wind one coil as neatly and tightly as possible and wind the other one randomly, loose and messy. Now compare their magnetic field strength at the poles when they are powered by the same DC current. You will find that the field from the neatly-wound coil is stronger. Why? Simply because more of the turns are closer to the core. That's all. Now sweep both coils with AC and look at the resulting waveform. You will notice that the randomly-wound coil is "noisier" or rather has more complex waveshapes at certain frequencies than the neatly-wound coil does. This is because the _distributed_ inductance of the random windings is "lumpy" and disturbs the internal field, and ditto the distributed capacitance within the windings. The tightly wound coil will also dissipate heat less effectively and will be less affected by magnetostriction in the windings.
5. Take a coil and a capacitor. Hook them together, one end of the cap to one end of the coil, the other end of the cap to the other end of the coil, making a complete circuit loop, a LC tank. Are the components in series, or are they in parallel? Think about it. Also compare the resonant frequency of a series tank with a parallel tank made of the same components.
6. I'll bet Farmhand is right about using resonance in a pulse motor, too. If you think about it, a pulse motor that is self-triggered like a Bedini or even one that reads a fixed sensor then triggers a coil after a proportional delay, that tries to accelerate until it reaches equilibrium with its total drag... is a mechanically resonant situation, attempting to "grow' the RPM, which is only limited by the "Q" of the system: its power dissipation from bearing and aero and eddy drags. If this could be combined with resonant coils using minimum power (because of the minimized AC impedance) it could be a significant innovation (if it is an innovation; I am not familiar with the literature so I can't say if motors using resonant coils are already out there in the wild.)

[gyulasun]

Hmm...so Tesla had a LC tank circuit without capacitor , very clever. My question : what kind of LC circuit it is ? Series or parallel ? Or maybe it depends how you connect things together ?     
....snip....

Hi forest,

Series or parallel?  Well, it is BOTH...  The distributed capacitance between the parallel wires makes the coil resonant at many frequencies, in fact you can consider the parallel wires as a transmission line.  Amateur radio operators use coils made from coaxial cable and use it as a frequency selective switch for their short wave antennas. See this link for such 'coaxial' coil:
http://vk1od.net/antenna/coaxtrap/index.htm   and scrolling down in that link you can see how the impedance of such coil (connected as described in the Tesla patent) depends on the frequency:
http://vk1od.net/antenna/coaxtrap/coaxtrap10.png 

Of course these coils work from the some MHz frequency ranges and much higher, and if you wish to bring down the operational range even to the some ten kHz range you would have to increase the distributed capacitance significantly between the parallel wires.  A good approach to do this is to use insulated rectangular wires and wind them in parallel with their flat sides facing each other to increase the capacitor surface areas or use flat copper or Alu ribbon or foil with high dielectric insulating material sandwiched in-between (just follow the formula for flat plate capacitors, C=(eps*A)/d where eps is the dielectic constant for the insulating material, A is the surface area and d is the distance between the facing metal surfaces). 
Of course there are practical limitations on building such bifilar coils to be resonant ,say, in the some 10 Hertz range.

Gyula