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Author Topic: Tesla's "COIL FOR ELECTRO-MAGNETS".  (Read 440237 times)

Offline Turbo

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #615 on: January 14, 2014, 11:48:11 AM »
A funny shaped piece of wire. Depends what you use it for.  ??? I don't get it, no current no power, no current no magnetic field = no magnet.

Voltage causes current, no voltage no current.

.

No current, no loss.

Maybe this is not the correct thread for me to respond either.



Offline Farmhand

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #616 on: January 14, 2014, 12:02:13 PM »
I just scanned the Patent and there is no mention of "resonance or resonant frequency ect." in the patent, so we can forget those "terms" in their strictest sense when talking of the patent.

Those are terms I used to describe the tuning of the capacitance to the Inductance,  and is how I describe tuning a resonant system to a load. I would describe right or wrong that Power Factor correcting is tuning the system to resonance on load. Maybe it's wrong to say that but that is what I mean.

Actually I guess tuning a resonant system to a load to get the most power dissipated as possible is more like "Impedance matching".

I don't see anywhere in the patent itself where Tesla himself mentions resonance or resonant frequency ect., someone should have mentioned that. Better late than never I suppose.

..

From experiment with resonant setups like the one in the picture previous page, I can say that when at resonance if I add certain loads the input drops, the tank voltage drops, and the activity drops, but with a simple tuning of the output parallel tank the activity, the tank voltage and the output power can be controlled right up to max and the more activity and output the more input power it takes from the battery. If the setup is finely tuned that is.

..

How about placing a piece of flat steel in close proximity to the coil to simulate a load for testing ? Induction heater.

..

Offline conradelektro

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #617 on: January 14, 2014, 01:14:13 PM »
New video about the magnetic field strength of my two pan cake coil. Nothing new, I just used my power supply as a variable current source (as MileHigh taught me). So far I only used this "current feature" of my laboratory power supply to limit the current when testing new circuits (so that I did not fry too many transistors).

 http://youtu.be/tvDUAcC1hbk


@Farmhand, MileHigh and Turbo:

I really like the discussion of this Tesla patent and the related "resonance and capacitor issues" (series or parallel LC circuits; impedance) because I only have a very muddled understanding of it. I will take some time till I understand the many posts, but then I will be back with questions.


@Magluvin and all:

I think we all are aware of the "high Voltage between adjacent wire turn" issue when talking and thinking about bifilar coils. The crucial problem is to describe the actual consequences.

- The known consequence of the "higher Voltage between adjacent wire turns" in a bifilar coil is the higher self capacitance (and the resulting lower self resonance frequency of a bifilar coil compared to a similar monofilar coil). This is nothing new in principle and no other effects are described in accepted science.

- Now there is a lot of esoteric and hype (or magic as I cynically like to call it) about alleged effects. I would like that someone describes at least one of these "magical effects" in clear and measurable terms. What is this "additional feature" of a bifilar coil (in comparison to monofilar coils). (Please do not say it is the high Voltage between adjacent turns).

- I have the suspicion that many people talk and write about "additional features" but can not really say more about it than the tiring "high Voltage between adjacent wire turns". Yes, there is "high Voltage between adjacent wires", but what does it cause (besides higher self capacitance)?

- I want to measure "unique features" (magic) of bifilar coils (besides the tiring "high Voltage between adjacent turns" which results in a higher self capacitance), but I do not know what to measure and nobody could tell me so far? (Some say there is nothing special, which is o.k. But the ones who believe in something special in bifilar coils should describe the effect more clearly.)

Greetings, Conrad

Offline Farmhand

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #618 on: January 14, 2014, 02:33:41 PM »
Well, the way I measured the coils in the second post gave me a different result altogether than this time. I remeasured the two coils and got a much higher frequency this time for both because I used the 10 K resistor on the ground leg of the function generator this time. I'll take time as soon as possible to update that first post to add the second set of measurements and explain there.

Anyway this time using a sine wave signal at full amplitude on the signal generator I get a frequency showing maximum wave amplitude at about 2000 kHz for the bifilar coil and about 2300 kHz for the monofilar coil as is, both have an Inductance of about 400 uH. If I put 115 pF in series with the positive lead of the Function generator on the monofilar coil it changes to about the same as the bifilar coil at around 2000 kHz. A difference of about 300 kHz.

This is a bit odd because going by the calculator online here - http://www3.telus.net/chemelec/Calculators/LC-Calculator.htm it would suggest a difference of only a few of pF between 12 pF and 16 pF along with the 400 uH to get those frequencies.

If I put the 115 pF in series with the bifilar coil it seems to increase the frequency required for maximum amplitude a bit if anything, maybe by as much as 100 kHz.

My Function Generator is very dodgy, it drifts a bit and is not so accurate, I need to get a digital one or something that will hold frequency with fine resolution.

The test setup I used tonight was the same as in the second post of this thread except that the 10 K Ohm resistor this time was in series with the Signal generator ground lead.

Cheers

AHAH, I read back and i will try with the 1 pF decoupling capacitor. And I can try an exciter coil as well. Will take some more time. The 115 pF of the scope is significant for these coils..


Offline conradelektro

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #619 on: January 14, 2014, 03:34:42 PM »
Well, the way I measured the coils in the second post gave me a different result altogether than this time. I remeasured the two coils and got a much higher frequency this time for both because I used the 10 K resistor on the ground leg of the function generator this time. I'll take time as soon as possible to update that first post to add the second set of measurements and explain there.

Anyway this time using a sine wave signal at full amplitude on the signal generator I get a frequency showing maximum wave amplitude at about 2000 kHz for the bifilar coil and about 2300 kHz for the monofilar coil as is, both have an Inductance of about 400 uH. If I put 115 pF in series with the positive lead of the Function generator on the monofilar coil it changes to about the same as the bifilar coil at around 2000 kHz. A difference of about 300 kHz.

@Farmhand:

Just to make sure we use the same measurement method I attach two circuit diagrams depicting the "classical method for self resonance frequency measurement" and the "self resonance frequency mesurement with an exciter coil".

I agree that for 2.3 and 2 MHz a 1 pF decoupling capacitor to hide the ~100 pF of the probe is essential. I had great trouble to do consistent measurements between 1 MHz and 9 MHz without the 1 pF decoupling cap.

Greetings, Conrad

Offline conradelektro

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #620 on: January 14, 2014, 03:43:58 PM »
@Farmhand:

Just to make everything absolutely clear I also attach a circuit diagram for testing a "loaded coil" (coil with a parallel capacitor to enforce a particular resonance frequency).

I know that you have much more experience than me, I just want to match our measurement methods to be able to compare results.

I have no clue how to measure the resonance frequency of a series LC tank?

Greetings, Conrad

Offline synchro1

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #621 on: January 14, 2014, 04:23:20 PM »
Hey Sync

Where is the diode and cap?  You have 2 resistors in parallel across the coil. Or is that the way they tested it?

Mags

@Farmhand,

First of all the "Synchro coil" is a series bifilar coil and is on topic for this thread!

@Magluvin,

That's just the way they tested it. Conradelektro goes on to point out a further test for spontaneous charge with a capacitor and diode, but he failed to use an electrolytic capacitor. These deletions and substitutions were radical departures from my original design.

@Conradelektro,

You ask what the hi-voltage potential does between the bifilar wraps. What does Ohms law tell you about high voltage? Ohmic resistance is inversely proportional to voltage. Radio waves encounter practically no resistance whatsoever. A spark can be detected in the far reaches of outerspace.

Milehigh calls my nail and paperclip test a grandiose claim. The Tesla series bifilar pancake coil was a bulwark of the scrap yard industry for nearly a hundred years. There were tens of thousands of these of these kinds of electromagnets all throughout America. The thick wire coil sat over an iron plate. There was a liter size capacitor and a six volt battery inside. The cab controls consisted of a double throw blade switch and a volt meter for the capacitor, with a DPDT to reverse for deposit. The magnet was suspended from a crane. Now the balde switch would charge the capacitor one way  from the battery then discharge the capacitor over the scrap and permanently magnetize it to the iron plate for movement. A second reversed impulse from the capacitor released the scrap!

Milehigh calls my results Grandiose! It's no no wonder why he attracts a plethora of abuse from me!

The Ed Leedskalnin PMH works by the same principle. It needs an "Impulse" to align the magnetic domains of the iron. The high potential between the bifilar wraps amplifies and transports this impulse to the iron ferrite to transmute the material to a permanent magnet.  

This video demonstrates the permanent magnet effect of BIFILAR COILS CONNECTED IN OPPOSITION:

http://www.youtube.com/watch?v=NRdVlWSLt_Y

Pay special attention to 1:20 in this video. You can clearly see the SPARK jump!


Testing the Tesla series bifilar pancake coil with pure D.C. power yields totally bogus results! Milehigh has seduced Conradelektro into conspiring with him to totally pervert the real attributes of Tesla's valuable invention, along with my "Synchro coil".

Offline synchro1

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #622 on: January 14, 2014, 05:48:33 PM »
I currently have two no limit open bet challenges to these pretenders, both have been shied from by them.

Offline gyulasun

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #623 on: January 14, 2014, 05:56:32 PM »
...

 how to measure the resonance frequency of a series LC tank?
...


Hi Conrad,

Would like to show you a drawing how you could measure the resonant frequency of a series LC tank, see attachment.  (I used some of the drawing symbols you also used in your own drawings.)

At resonance, as you surely know,  a series LC circuit has the lowest impedance which is equal mainly to the coil's DC resistance (usually out of all the L and C losses the coil wire resistance causes the highest loss).  This way, at resonance the AC voltage amplitude appears to be the maximum across the 50 Ohm non-inductive resistance, R, and if you sweep the generator above or below this frequency, the amplitude gradually reduces, how quickly it depends mainly on the Q factor of the coil.
I watched all your recent videos, they are good, thanks for showing them.

Greetings, Gyula

EDIT: perhaps the scope probe of CH1 as shown across the output of the function generator is not needed at all or if you wish to use it, then I suggest using also a series 1 pF coupling capacitor because the 100 pF cap of the probe can also influence the resonance of the series LC tank. 
A question: do your probes include the 10:1 division ratio or they are only 1:1 probes?

Offline conradelektro

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #624 on: January 14, 2014, 06:49:25 PM »
Hi Conrad,

Would like to show you a drawing how you could measure the resonant frequency of a series LC tank, see attachment.  (I used some of the drawing symbols you also used in your own drawings.)

At resonance, as you surely know,  a series LC circuit has the lowest impedance which is equal mainly to the coil's DC resistance (usually out of all the L and C losses the coil wire resistance causes the highest loss).  This way, at resonance the AC voltage amplitude appears to be the maximum across the 50 Ohm non-inductive resistance, R, and if you sweep the generator above or below this frequency, the amplitude gradually reduces, how quickly it depends mainly on the Q factor of the coil.
I watched all your recent videos, they are good, thanks for showing them.

Greetings, Gyula

EDIT: perhaps the scope probe of CH1 as shown across the output of the function generator is not needed at all or if you wish to use it, then I suggest using also a series 1 pF coupling capacitor because the 100 pF cap of the probe can also influence the resonance of the series LC tank. 
A question: do your probes include the 10:1 division ratio or they are only 1:1 probes?

@Gyula: thank you, as always you are helping very much.

Yes, my scope probes also have a 1:10 setting and should have a lower input capacitance of 15 pF at 1:10. I also have a 1:100 probe with an input capacitance of about 7 pF.


I just did the measurement you suggested in your post (the series LC circuit). I was just trying to do that but I put a 1 K resistor instead of the 50 Ohm resistor and went now where till I saw your post.

I was measuring a 10 nF cap as a tank capacitor for my monofilar pan cake coil.

The "parallel LC tank" (10 nF in parallel to the monofilar coil) showed a resonance frequency of 270 Kilohertz (measured with an exciter coil and "classical", also the calculator at this web site http://www.1728.org/resfreq.htm confirms the consistency of this measurement).

Now, according to this web site http://en.wikipedia.org/wiki/LC_circuit the "series LC tank" should have a resonance frequency of 270 Kilohertz as well.

And it does!

But the measurement of the "series LC tank"  (probe over 50 Ohm resistor) is much less indicative than the measurement of the "prallel LC tank" (probe over coil). There is a maximum at 270 KHz, but it is difficult to see. The Voltage peaks from 150 KHz to 350 KHz. If I had not known the resonance frequency from the "parallel LC tank", it would have been a less precise result.


Also interesting, with a 10 nF tank cap (and a resonance at 270 KHz) the probe capacitance of 100 pF does not matter at all. Also the higher self capacitance of the bifilar pan cake coil does not matter any more. I tried it with the bifilar coil as well.

This gives me the idea to wind helical coils with many turns (a bifilar and a similar monofilar) for further tests in order to be in 100 KHz range (rather than in the Megahertz rang like with my frugal pan cake coils).

Greetings, Conrad

Offline conradelektro

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #625 on: January 14, 2014, 07:55:37 PM »
I just did something for training:

The "1/2 Voltage, impedance comparison to a known resistor" to determine inductance of a coil, according to http://daycounter.com/Articles/How-To-Measure-Inductance.phtml.

And, the impedance of the pan cake coils comes out as 34 ┬ÁH (as it should).

See the attached drawings and scope shots.

I used Voltage "peak to peak" instead of RMS because it is easier to see on the scope. Is that good?

Greetings, Conrad

Offline synchro1

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #626 on: January 14, 2014, 08:10:41 PM »
"In this study, we combined an array of giant magnetoresistive (GMR) sensors with an array of Hall sensors to measure all three components of magnetic vectors with a high spatial resolution and visualize the magnetic field distribution on a 2-D plane. The sensors were arrayed in a matrix arrangement such that the limitation to the number of sensors could be overcome. To test the device, "we generated a magnetic field using a pancake-type magnetizer" and a cracked magnetized ferromagnetic specimen and imaged the vectors. We obtained a spatial resolution of 0.78 mm in the z-direction with 1024 Hall sensors and 2.34 mm in the x-direction with 100 GMR sensors. Moreover, the x and z components could be imaged at 6 fps. The proposed device is promising for application in magnetic flux leakage detection".

Additional fact about the Pancake Magnetizer coil:

"It is well known that the inductance of a pancake type coil put on the metallic specimen changes according to the electromagnetic properties of the metallic specimen"


It's possible to run DC current through Leedskalnin's PMH and get zero magnetic effect!



Offline gyulasun

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #627 on: January 14, 2014, 09:31:38 PM »
Hi Conrad,

Okay on your probes, then you have choices on their input capacitance 'selection' but then the 1:10 or 1:100 choices influence the amplitude sensitivity of the measurements of course what you should compensate either by increasing the generator output or choosing the most sensitive scope input range and both of these have limits.

Regarding your observation on the low indication sensitivity of the series LC measuring setup, it happens because the two 50 Ohm resistances in the circuit reduces very much the natural quality factor, Q of the LC circuit (50 Ohm from the generator and another 50 Ohm from the R resistance (where you also used 1 kOhm), alltogether a 100 Ohm shunts the series LC tank, ok?

Because in this measuring setup, the output resistance (impedance) of the generator adds in series with the series LC circuit, effectively increasing the loss resistance of the series LC tank,  ideally a generator resistance (impedance) of much less than 50 Ohm would be needed, preferably near to 1 Ohm or leven less but such a low generator output impedance can be had for instance from amplifiers designed for low output impedance.
OF course, alternative solutions do exist, see this link http://www.circuitstoday.com/q-meter where a 0.02 Ohm is connected in series with the coil to measure its natural Q and in that circuit a function generator can substitute the oscillator, no need for the thermocouple voltmeter either and at the output your probe with a series 1 pF would serve as the resonance voltage indicator and the C resonating capacitor would be your 10 nF or any other even some 10 pF capacitor value. You would terminate the gen output with a 50 Ohm resistor and connect say a 0.1 Ohm  non-wire-wound resistor in series with it to drive the coil, that is all. You may wonder whether this is a series or a parallel LC? from the generator output point of view it is a series LC where you check voltage maximum across the tank capacitor.


By your choosing a tank capacitor of 10 nF i.e. in the some nanoFarad range, this simply masks any detuning effect of
any probe capacitance or coil self capacitance they would otherwise manifest, as you found such manifestation earlier in the lack of the 1 pF coupling capacitor.


...
I used Voltage "peak to peak" instead of RMS because it is easier to see on the scope. Is that good?
...

In this case it is good because their ratio is the same as it comes out from their rms value ratio, ok?

Greetings,  Gyula


Offline Farmhand

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #628 on: January 14, 2014, 10:33:17 PM »
Conrad, can you please give us a break down of the results of the series  test as compared to the parallel test, what is the difference if any ? Is the series resonant frequency of the bifilar coil lower than the series resonant frequency of the monofilar coil ? Is it the same as the parallel resonant frequency ?

I must say Conrad with the very good assistance you are getting you have gained some impressive results, I'm not sure I need to continue with such small coils.

Here is a thought Conrad, to test my theory that the applied voltage can vary the extra capacitance secured by the bifilar coil or any coil I guess, I intend to make a bifilar coil with the turns spaced so that with only a few volts or the meter used shows the capacitance secured between the two open windings is less than when they are wound closer together, thicker insulation more plate gap in the capacitor.

That will allow me to attempt to get a resonant frequency with only the few volts with the increased "plate gap", then also to get a resonant frequency with a higher voltage that should secure a higher capacitance between turns and therefore a lower resonant frequency of the coil for a higher applied voltage, within limits. If the gap that makes the capacitor is too wide for the applied voltage the capacitance secured should be less, just like if the plates of a capacitor are brought closer the capacitance reading increases. A parallel plate capacitor with a plate gap of 10 mm will give less capacitance secured in practice when only charged with 1 volt than when charged with 1000 volts, is what I am imagining to describe an extreme. If I'm right or wrong is another matter.

It might help if I learn how the meter works.

Cheers

Offline Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #629 on: January 15, 2014, 01:12:27 AM »
Decided to go a different route with winding the 2in bifi.  I have a few bobbins of the same wire 42awg that the wire broke before finishing the wind on my Lasersaber ez spin motor . Sooo, I can use those to wind a bifi ez spin coil. This way Im already set up to test comparable coils with the motor also. Been wanting to do this anyways. For some reason I feel a bit inspired. ;D And it wont take as long to wind and should work as a good comparison test of normal vs bifi.

The coils are just over 3000 turns, 650ohm, 81mh single strand.  About 450 ft of wire, of which should give me decent capacitance. Compared to some other coils I have made, I guestimate near 50nf.  Which is around 2500hz. My ez motor running near 400rpm can feed a bifi with just over 4kz with all coils in series using the least amount of current. 24 NSNS mags on the rotor, 12 full cycles per rotation. The motor is a torque'y lil monster with all coils in parallel at 27ohms. I have to remake the rotor to run it like that so the magnets dont become projectiles. Havnt let it go to full speed. Was scared. ;D

For me, it pays to think before I do. To test the 2in coil with a motor, I would have to make a rotor that has mag spacing according to the coil width. But the ez is set up so that a N mag is approaching the coil while the S mag is departing. So output is a nice sinewave where the coils are always being induced by the mags while the rotor turns. Perfect to operate the bifi, I can get the rotor to go much faster running just one of the drive coils. More current, as compared to 24 coils in series, 15kohm vs 1 coil 650ohm. So no doubts the motor will be able to hit the bifi resonance even if my capacitance doesnt reach my estimate. And other comparison tests can be done.

Mags