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Author Topic: Tesla's "COIL FOR ELECTRO-MAGNETS".  (Read 505754 times)

Farmhand

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #120 on: May 18, 2013, 12:38:28 AM »
Tesla's Claims in the patent are correct that is the main thing.

Quote
What I claim as my invention is
 
1.  A coil for electric apparatus the adjacent
convolutions of which form parts of the
circuit between which there exists a potential    45
difference sufficient to secure in the coil a capacity
capable of neutralizing its self induction
as hereinbefore described.

2.  A coil composed of contiguous or adjacent
insulated conductors electrically connected        50     
in series and having a potential difference of
such value as to give to the coil as a whole a
capacity sufficient to neutralize its self induction

as set forth.  NIKOLA TESLA

Here is what I think the claims are saying. If the voltage is too low, then the distance between the capacitor "plates" is too great for the capacity to be effectively used.
ie. If the conductors have insulation 5 mm thick then using 1 volt won't utilize the capacity very well and the capacity will not then contribute to the lowering of the resonance frequency. Kinda like trying to use 1 volt with a HV parallel plate air capacitor with 10 mm spacing between the plates, it won't work very well.

It makes sense to me.

Weather or not the coil is special is not a concern to me. The patent claims are correct and I think that is what he means when he says the words in bold above.

Rather than trying to argue angles or such things why not just take the claims and find if they are correct or not. Tesla's patents do not need to be dismissed or defended if they are making claims that are true. Simple. Any claims not made by Tesla are other peoples making.

..

Farmhand

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #121 on: May 18, 2013, 01:00:56 AM »
MileHigh, I do understand, it is important to stay grounded. But I don't know why you would assume all I want to do is spin a rotor faster when I am doing load tests. I want to power loads if I can, if not it won't go past a prototype. What would be the point ?

Same with the pulse motor build off. What do they judge on ? Is it the prettiness or the micro power draw for no work ?
Or is it the most work for the least cost like what motors are for ?

My circuit has provision for voltage increase so I don't need to wait for 5 minutes for the rotor to speed up, it takes 5 seconds instead maybe 8 max.  :) And that's fair dinkum, no kidding.  ;D

Have you seen a pulse motor before with my design ? Why can't it be comparable to a conventional motor ? And flexible.

I'm not claiming any free energy, I'm just making things.

Tesla never claimed any OU, he had devices that collected energy from the environment like a solar panel or wind turbine does.

All the crazy OU claims are made by others.

Cheers

MileHigh

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #122 on: May 18, 2013, 01:06:36 AM »
Farmhand:

I am not sure exactly what he means by "neutralizing its self-induction."  This is 19th century technical English that is sometimes also reworded for 19th century lay people.

I interpret it as the coil is self-resonating such that the inductance is "occupied" and part of an LC resonator.  It doesn't mean that it's "neutralized" and can be more easily energized.

Alternatively, from an AC excitation perspective we know that a self-resonating coil will not exhibit the property of AC inductance anymore with a 90 phase shift and a power factor of zero.  The inductance will be "neutralized" and appear as an AC open circuit, or as an AC short circuit.  Do you think that's what it means?

I asked Magluvin and he bowed out and threw the question back at me.  What do you think?

One thing is for sure, there is nothing at all in the patent about pulse motors or using the coil configuration in a pulse motor.  Nada.

Timing and the related conduction angle is probably the most important aspect to the operation of the pulse motor.  All pulse circuits are based on timing analysis.

MileHigh

P.S.:  Not sure what the criteria are that they use for the judging in the pulse motor build-offs.  Certainly "coolness factor" carries a lot of weight.

Farmhand

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #123 on: May 18, 2013, 01:18:45 AM »
MileHigh, I hope you were not referring to me when you said about claiming "the power comes up from the ground". I never claimed that. Not ever.

Yes I do realize the timing of the pulses and the resulting current times are important that is why I am experimenting with it.

And I can't recall claiming that a Tesla type bifilar coil would make a better pulse motor coil, my coils are wound normally why would I do that ?

I think I mentioned that the neutralizing of the inductance allows the current to flow as if the was no self inductance, just the DC resistance.

Didn't you read the patent ? Lines 40 to 45.

Quote
I have found that in every coil there exists 40
a certain relation between its self induction
and capacity that permits a current of given
frequency and potential to pass through it with
no other opposition than that of ohmic resistance
or in other words as though it possessed no self induction. 45

Quote
What do you think?

I'm not going to answer directly your question because it doesn't really matter what I think, what matters is what is.

Cheers

MileHigh

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #124 on: May 18, 2013, 01:35:21 AM »
Farmhand:

I wasn't attributing those statements to you.  Sorry I am tired and was not clear enough.

Thanks also for pointing out the lines in the patent again.  There Tesla is clearly describing a series LC resonator.  So a series LC resonator can become an AC short circuit at the resonance frequency.  That means AC power will flow straight through the series LC resonator except for the power dissipated in the series resistance of the wire.  I made reference to that in my previous posting.

Can that property of series LC resonance be used to advantage in a pulse motor?  Do you observe it in anybody's pulse motor?  I will leave that up to you guys to explore that.  Certainly it looks like the tests in the YouTube clips make a stand-alone coil in self-resonance appear to act like a parallel LC resonator.

Quote
I'm not going to answer directly your question because it doesn't really matter what I think, what matters is what is.

I have to disagree with you here.  If this concept is one of the central themes for this thread, surely everybody should be on the same page as to the understanding of exactly what it means.  If you don't then it just becomes a catch phrase with no substance behind it.

MileHigh

Farmhand

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #125 on: May 18, 2013, 01:53:11 AM »
No Problem then, Yes the resonance is the key to a lot of his stuff but not all, some of them it is just better to have it and some don't have it.

As far as pulse motors and series resonance goes, I just do what comes naturally to me and what seems like a good idea because there is no law against it and it stops me injuring myself doing other harder work type stuff, I've got a busted neck. I think in my setup there are a lot of different things going on and I make no real claims as yet except I get two driving phases from one switching phase and there is energy returned and adds to the potential of the circuit, that's resonance in one way I think.

But I as far as I can tell the parallel capacitor in my Tesla coil DC HV primary circuit is sometimes in parallel and sometimes in series with the supply.
It's in parallel because it's across the voltage charging it and it's in series because it's the only load when it's charged, so it must be. It is only in parallel with the primary when the spark gap is conducting, the close coupling and the Large primary diameter means it just rings along with the secondary when not excited like it's not there, almost.  :D My guess is it actually causes havoc and it is definitely not a continuous wave transformer. But I will build one one day.

As for series resonance capacitors in Tesla coil primary circuits they are in parallel with the primary when the spark gap conducts as well. Are they not ?

Cheers

Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #126 on: May 18, 2013, 02:05:31 AM »


I asked Magluvin and he bowed out and threw the question back at me.  What do you think?



Yes I did throw it back at you.  ;) It seems no matter how I describe it you continue to post as if I have not and keep questioning "What does neutralizing self inductance mean?"

Im tired of it already. ::) Im not here to teach you how to read. Im not here to give links to the definitions of 'neutralize' nor 'self inductance'. Should not have to with your self proclaimed experience from '30 years ago'.  I know you know some things. Why cant you understand what that statement means "neutralize self inductance'? Between all of us here in the thread, you are the only one that seems to have a problem with it.  What gives?

And the idea that a messy coil is no different than a tight, neatly wound coil beyond saying that different winding techniques from the norm have no differences either, I think you need to hit the books before you make such claims. ;)

Mags

Farmhand

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #127 on: May 18, 2013, 03:11:09 AM »
I'm interested in what you're doing Mags because you have a bike, I like bikes with motors.  ;) And I like all different kinds of motors too and engines and other machines as well.

One example of a good use for a pulse motor might be to raise water, I have rain water tanks both elevated and ground level, if I had a reasonably powerful and efficient pulse motor it could move air as a fan and pump water from the ground tank to the elevated tank when I want it to so then the water can flow back down and out of the tap under it's own weight. It doesn't matter how long it takes to pump 1000 litres of water if the motor is running all the time anyway as a big fan with a shaft and some coupling arrangement to the pump. It gets mighty hot here in summer usually so fans go day and night. No air con here.

The energy to run the motor would be free from the sun and it could run easily non stop from my solar charged batteries using an amp or two when it's hot outside.

A free energy machine might be a machine that uses lots of free energy provided by the sun. hehehehe

pulse motors would seem to be able to work on bikes as a motive aid, so that might be fun.

If something works for you Mags do it. We're here to talk and share and help each other. I seem to find myself disagreeing with everyone at some point.

I think we all should remember that we all have different wants and objectives. I like to build stuff and learn new things in my own way and I find these forums have helpful people even if I do need to argue the information out of them.  :)

Cheers

MileHigh

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #128 on: May 18, 2013, 03:27:05 AM »
Really Magluvin?

I am going to quote you:

Quote
We talked about the capacitance neutralizing the self inductance the other day.
If we have a coil with a cap across it, and then we just apply a dc source across it, the cap will charge virtually instantly, but the inductor wont. This might imitate a neutralizing of self inductance of the coil, where the current flows easily through the cap. We are talking about applying DC here.

If the capacitance is 'in' the coil, well that current that charges that capacitance goes 'through the coil' neutralizing the self inductance. And if it neutralizes self inductance, then maybe we could think, does that mean that the magnetic field is neutralized also, or just the effect of impedance is neutralized and outer magnetic field is unaffected. If so then initially there could be a very intense field pulse, as compared to a slowly building standard inductive field build, depending in the inductance.

That internal capacitance is charged through a coil that can make an external field like any other coil and the impedance is neutralized. So until this capacitance is charged, this coil might be acting like a super electromagnet. Sounds like a heck of an idea to patent. (http://www.overunity.com/Smileys/default/wink.gif)

If we consider the cap connected to a coil, there probably isnt any purpose for it in the DC world. But here the capacitance is in the coil, and in my opinion, there should be a difference.

Also I stated earlier about the ability of holding power over time. Well if the field is huge in the beginning through the object being held, this may give us that stronger hold over time, instantly instead.

Quote
Thats not true. If there is capacitance in the coil, it should be ignored, right? If we were to put a cap across a normal coil as you say, if we pulsed it like in a pulse motor, the very first thing the circuit sees is the capacitance and the circuit charges it before much happens in the coil. But in the bifi, the charging of the capacitance happens through the windings of the coil, and since the capacitance neutralizes the self inductance till the capacitance of the coil is fully charged. Talking a DC pulse of course.

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:

Quote
"What do you and Farmhand and possibly others really mean when you say "neutralizes" in this context?"

And possibly others? lol  Tesla had the patent and he said it.  What do you think it means in your context?

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:

Quote
I know you know some things. Why cant you understand what that statement means "neutralize self inductance'? Between all of us here in the thread, you are the only one that seems to have a problem with it.  What gives?

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.

Quote
And the idea that a messy coil is no different than a tight, neatly wound coil beyond saying that different winding techniques from the norm have no differences either, I think you need to hit the books before you make such claims."

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

Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #129 on: May 18, 2013, 04:43:20 AM »
I'm interested in what you're doing Mags because you have a bike, I like bikes with motors.  ;) And I like all different kinds of motors too and engines and other machines as well.

One example of a good use for a pulse motor might be to raise water, I have rain water tanks both elevated and ground level, if I had a reasonably powerful and efficient pulse motor it could move air as a fan and pump water from the ground tank to the elevated tank when I want it to so then the water can flow back down and out of the tap under it's own weight. It doesn't matter how long it takes to pump 1000 litres of water if the motor is running all the time anyway as a big fan with a shaft and some coupling arrangement to the pump. It gets mighty hot here in summer usually so fans go day and night. No air con here.

The energy to run the motor would be free from the sun and it could run easily non stop from my solar charged batteries using an amp or two when it's hot outside.

A free energy machine might be a machine that uses lots of free energy provided by the sun. hehehehe

pulse motors would seem to be able to work on bikes as a motive aid, so that might be fun.

If something works for you Mags do it. We're here to talk and share and help each other. I seem to find myself disagreeing with everyone at some point.

I think we all should remember that we all have different wants and objectives. I like to build stuff and learn new things in my own way and I find these forums have helpful people even if I do need to argue the information out of them.  :)

Cheers

If i were to conjure up your idea right here, this would be my approach..  ;)

First we have to know how much pressure we are dealing with to pump water up. Then purchase a pump that can handle the pressure. If it is going to be a pulse motor, I might suggest a flywheel rotor to keep the wheel going between pulses, as I imagine the pressure of the water in the up tube to possibly be quite great and working against the rotor being driven. As for the coils, use as many or more than the number of magnets on the rotor/flywheel and tie the drive coils in series. Here is why in series...

Like speaker systems, if you power a speaker 4ohm at 100w, and get 100db, you can now use 2 speakers to get more db with the same input. ;)   Here is why... and how...

The single speaker, 4ohm, with 100w signal produces 100db.  If we double the input to 200w we get an increase of 3db to 103db. 
Now, when we series wire 2 speakers, and input 100w, each speaker will only see 50w but we get 103db, for the same input 100w. Follow me.

1 speaker at 50w only delivers 97db, a loss of 3db. Double the wattage, increase 3db. Halve the wattage decrease 3db.

So we have 1 speaker with 50w putting out 97 db. WHEN WE ADD ANOTHER SPEAKER WITH AN INPUT OF 50w, WE GET A 6db INCREASE!!!! :o :o ;D ;D

How can that be?  But it is. We get the same output from 2 speakers with 100w total input as we would 200w into 1 speaker!!  ;)   

Thats why coils in series. More efficiency. 

4 speakers in series. 4 ohm each, now 16 ohms and 25w/94db each 100w total.

1 speaker 25w     94db

2 speakers, 25w each, 50w total    add 6 db   100db

Add 2 more speakers for a total of four speakers and input total of 100w     106db!!!

1 speaker would need to be powered with 400w to produce the 106db!!!

lol, now tune port those boxes to 30hz and run 100w total 30hz in, add another near 8db typical. Thats some resonance effects for ya. ;) Thats like 1 speaker with 800w but only 100w in. :o ;) Geddit? 

And the tuned box at 30hz, the speaker cone isnt visibly moving, but the port air is, a lot.   Did custom car audio professionally for almost 20 years. Biggest system 17kw, 24 12s and way too many mids and highs for my taste. I like real stereo, none of that surround sound distracting mumbo jumbo. Im a purist. ;D Close your eyes and you can see the band out in front of the car in your mind. Difficult to do but not impossible.


I believe these pulse motors can be thought of this way.    ;)   In fact, its just about a direct correlation. ;)   Electrical input to magnetic field to motive force. Same thing. ;)

Now, if you were going to make an electric car. Would you use 4 motors, 1 in each wheel, or just 1 motor?   ;)

Mags

Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #130 on: May 18, 2013, 05:19:36 AM »
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. :P

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

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #131 on: May 18, 2013, 07:52:33 AM »
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 ?  :o  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

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #132 on: May 18, 2013, 08:52:51 AM »
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

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #133 on: May 18, 2013, 01:36:56 PM »
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

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #134 on: May 18, 2013, 03:47:49 PM »
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 ?  :o   
....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