Tesla's "COIL FOR ELECTRO-MAGNETS".

[gyulasun]

...
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.  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 ?

Yes,  I also understand the input capacitor for the primary coil in a Tesla coil setup is basically in series with the primary coil, it charges up from the AC input source and then the spark gap fires, connecting the capacitor in parallel with the primary coil.
(A useful link is here, out of many others: http://www.richieburnett.co.uk/operation.html )

Gyula

[MileHigh]

TK:

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.

In theory there in no need to have low inductance.  In some kind of LC arrangement, there will always be a resonant frequency whee the two reactances cancel each other out.

In terms of a practical build I would assume that you are correct in the sense that they would want to make the device resonate at a reasonable frequency.  Do you know what Tesla did with these types of coils?  Were they used to generate a short high-frequency oscillation to drive other circuits or something akin to that?

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.

Let's not say the same length of wire but rather say the same number of turns.  The field strength at the poles will be nearly identical, probably out to a few decimal places.  There will be very little difference in field strength due to the wire loop distance from the core.  The flux going through the from an inner loop and and an outer loop will be nearly the same because the core induces all the flux to flow through it.  When you sweep the coils with AC within a reasonable frequency range the coils will behave essentially identically.  You will not encounter any "lumpiness" and I don't know what you mean by "distributed inductance."  Assuming that you are sweeping the coil with a sine wave, then you won't see any complex waveshapes.  The coil is a linear device be it neatly wound or messily wound and therefore it can't "generate" it's own frequency content, it can only filter the input sinusoid waveform and output a sinusoid at the same frequency.  It can't generate any harmonics by itself because it's a linear device.

What's the context here?  It's a pulse motor.  So the point is that if you are going to make a drive coil or a pick-up coil for your pulse motor, do you need to spend a few hours slowly winding the coil and ensuring that the wires are as neat as possible?  The answer is no you don't, you can wind your coil in 10 minutes and it will work perfectly fine in the pulse motor.  The inductance will be the same, the magnetic field pattern will be the same, and the frequency transfer function within a reasonable frequency band will be the same.  That's the point, and it's an important one.  Separate the wheat from the chaff when it comes to what's important and what's not important if you are going to build a pulse motor.  Learn the basic fundamentals and apply that knowledge when you do a build.  Don't work in a "voodoo electronics" world, work in the real world of electronics.

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

It's not a mechanically resonant situation, it's a situation that reaches a quiescent RPM where the average power input is balanced by the average power dissipated.  The pulsing is at some "operating frequency" as opposed to a "resonant frequency."   You might recall that I made the same point about a Joule Thief.  It's very encouraging to see that Farmhand is looking at both the voltage and the current waveforms in his setups.  If he can exploit some kind of coil resonance that is aligned with the operating frequency of the pulse train that drives the motor will be interesting to see.  I know that Itsusable added capacitors across his pick-up coils or drive coil(s) or both in his clips where he investigated pulse motor resonance.  In other words, the only way to get a pick-up coil to resonate with the passing rotor magnets is to add a capacitor across the pick-up coil to bring the resonant frequency down.  I looked at those clips about six months ago and to the best of my recollection he did not have any remarkable findings to report.

MileHigh

[synchro1]

@Milehigh,

Four ways to increase electromagnetic strength. Your posts limit the ways to the first two!

1.- Increase the number of coil turns.
2.- Increase the current passing through the coil.
3.- Increase the voltage passing through coil.
4.- Tight wndings.

Electromagnets:

Moreover, you're dead wrong about another thing. You're good at covering outrageous falsehoods like these with slick sophistry!

"When the wire is wound into a coil, all the individual magnetic  fields line up. They flow through the center of the coil and back out around the  outside. The tighter the coil is, the greater the magnetic field."

Read more:  How Does the Tightness of the Coil Affect the Strength of an Electromagnet? | eHow http://www.ehow.com/how-does_5043013_tightness-coil-affect-strength-electromagnet.html#ixzz2TfTsSVWu

[gyulasun]

....

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!!!!

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. 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. 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

Hi Mags,

Your series speaker system connection with its higher output possibility at the same input power reminds me to an experiment (I mentioned it to Farmhand in the other thread) by Ian from some years ago. See his post here:
http://www.overunity.com/1754/pulse-motor-video/msg35080/#msg35080

His idea of using more and more identical coils in series and also in parallel combinations so that the resultant coil inductance and DC resistance remains the same as for the single coil sounds good (albeit it would not insure excess output), efficiency would increase for sure.  (Back then I toyed with the idea of using a rotor disk of 30-40 cm OD and fixing many small but strong magnets on it while the many stator coils would be arranged like Ian described, using a moderate number of windings of thicker wire but I did not have the mechanical means for the bigger rotor mechanics.) 
While I do not fully agree with Ian on all his statements as a final outcome, the more and more total flux involved can give more and more output torque for sure,  versus the single same coil - single same magnet setup (albeit the COP > 1 is still a question with it).
Ian compared his single coil pulse motor setup to a 8 coil setup, using the same rotor mass and same input power for both setups. Here is his single coil description http://www.overunity.com/1754/pulse-motor-video/msg31932/#msg31932 and here is his 8 coil setup video: http://www.youtube.com/watch?v=f4gAKrn5pl4 

So there seems to be an interesting analogy between the series speaker output power increase you observed and output torque increase by series coils in pulse motors, for both cases at the same input power.  (For the latter pulse setup the many coils could also be arranged in series and the series groups in parallel as Ian described above and each such coil would have its facing magnet on a big rotor, the torque increase would surely be significant.)

Gyula

[Magluvin]

Hi Mags,

Your series speaker system connection with its higher output possibility at the same input power reminds me to an experiment (I mentioned it to Farmhand in the other thread) by Ian from some years ago. See his post here:
http://www.overunity.com/1754/pulse-motor-video/msg35080/#msg35080

His idea of using more and more identical coils in series and also in parallel combinations so that the resultant coil inductance and DC resistance remains the same as for the single coil sounds good (albeit it would not insure excess output), efficiency would increase for sure.  (Back then I toyed with the idea of using a rotor disk of 30-40 cm OD and fixing many small but strong magnets on it while the many stator coils would be arranged like Ian described, using a moderate number of windings of thicker wire but I did not have the mechanical means for the bigger rotor mechanics.) 
While I do not fully agree with Ian on all his statements as a final outcome, the more and more total flux involved can give more and more output torque for sure,  versus the single same coil - single same magnet setup (albeit the COP > 1 is still a question with it).
Ian compared his single coil pulse motor setup to a 8 coil setup, using the same rotor mass and same input power for both setups. Here is his single coil description http://www.overunity.com/1754/pulse-motor-video/msg31932/#msg31932 and here is his 8 coil setup video: http://www.youtube.com/watch?v=f4gAKrn5pl4 

So there seems to be an interesting analogy between the series speaker output power increase you observed and output torque increase by series coils in pulse motors, for both cases at the same input power.  (For the latter pulse setup the many coils could also be arranged in series and the series groups in parallel as Ian described above and each such coil would have its facing magnet on a big rotor, the torque increase would surely be significant.)

Gyula

Hmm, come to think of it, if they are in parallel, and just input less power we can get the same advantages. So what it really boils down to is the number of coils/speakers is what makes it better. So it can go one way or the other.  So having more magnets and coils, covering more surface area, more motive force for the same input.  A whole bunch of tiny magnets and tiny coils.     

Thanks Gyula

Mags