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Author Topic: Tesla's "COIL FOR ELECTRO-MAGNETS".  (Read 451087 times)

Offline Farmhand

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #630 on: January 15, 2014, 03:16:33 AM »
Mags that will get the frequency down no doubt, I'm considering winding some spirals, I've never wound a spiral for a particular reason, I'm thinking I will make them physically as large as is practical for me, and able to take fairly high voltages. Looking forward to all results, it is interesting stuff.

If it wasn't for the high frequencies of the Tesla coil setups and the large inductive field around the coils I would try to measure the voltages and currents in the setup at different states of tune.

I have no choice but to keep my experiments to bench sized arrangements for a while yet.

..

Offline MileHigh

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #631 on: January 15, 2014, 03:47:11 AM »
The description of the operation of the series LC circut.

So the setup is: function generator  -> capacitor -> coil  -> load resistor -> ground.  The function generator is outputting a sine wave at the resonance frequency.

We will just look a few "pieces" or datum points of the circuit, enough information so that if you wanted you could connect the dots and draw out a timing diagram.  If you draw out the timing diagram you will see all the pieces fit together and it should all make sense.  All that you need to know are a few basic facts about circuit analysis and how coils and capacitors work.

The first point to consider is deceptively simple:  If there is no resistance then the voltage output by the function generator must also be seen by the load resistor.  It simply has to be the case.

You can reword that like this:   The voltage output by the function generator plus the voltage across the capacitor plus the voltage across the coil is also the voltage that is seen at the load resistor.  It's almost like the voltage across the capacitor plus the voltage across the coil is always equal to zero.  Like those two components almost disappear.

Likewise, the current through the circuit is directly proportional to the function generator voltage.  It has to be the case, there is no other choice.

I am assuming that people understand how the voltages and currents work for capacitors and coils.

Now for some datum points:

What's happening when the function generator voltage is at it's peak?  We know that current must be the maximum.  Just as importantly we know that at the voltage peak the current is unchanging.  There is "micro spot" at the top of the sine wave peak where the voltage is constant and unchanging, therefore the current has to be unchanging.

Continued in part 2....

Offline MileHigh

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #632 on: January 15, 2014, 03:47:34 AM »
Part 2:

For coils we know that if the current is unchanging, then the voltage has to be zero, there is no other choice.
For capacitors we know that if the current flow is at maximum, the the voltage must be zero, there is no other choice.

So you can see that we have generated two datum points:

1 and 2:  At the top (and bottom) of the function generator sine wave, the voltage on the coil is zero, and the voltage on the capacitor is zero, there is no other choice.  (Note that this all works out, no voltage drops so the function generator voltage is seen at the load resistor, no other choice.)

Now let's consider when the output of the function generator is zero and rising.  We also know that the voltage is rising at the fastest rate of change here.  That means the current is also changing at it's fastest rate of change.

One more datum point:

With the fastest rate of change of increasing current, we know that the voltage across the inductor has to be at a maximum.  No choice, the coil puts a constraint on the voltage and fixes it at the maximum.

So look at this unique situation:  The voltage output from the function generator is zero.  But there is a maximum voltage across the coil, but we know that the voltage at the load resistor must also be zero.  There is only one solution to resolve this:  The voltage on the capacitor must be at an equal and opposite voltage as compared to the coil.  So there is the other datum point.

Then of course we know that if the capacitor is at a maximum voltage, that means it's fully charged to its maximum charge.

So what you end up with is this:  As the function generator outputs a sine wave at the resonant frequency, the coil and capacitor are in a kind of "voltage tug of war" that is a pair of pure and opposite sine waves, because when coils resonate with capacitors by definition you get sine waves for the current and voltage.  Note that the function generator output is also a perfect sine wave.   So you have a double resonating sine wave interaction with a sine wave from the function generator.  It's like the resonant part of the circuit and the function generator are two people that are perfect dance partners that dance together very closely in harmony but they never touch or disturb each other.  The male makes a move and the female moves perfectly in tandem and they never actually touch.

Sorry that was too long.  But there is enough information there to construct a full timing diagram:

Function generator voltage and current  (identical waveforms for the load resistor)
Coil voltage
Inductor voltage
Coil Energy
Inductor Energy
Coil + Inductor energy

Now if you are crazy enough to take the plunge, and you build a timing diagram starting from the few data points given, you should find that the waveform for the (Coil + inductor energy) is a flat line.  The flat line is telling you that the coil and capacitor are acting like an LC resonator with a fixed amount of stored energy.

So what that means is that when you first power up your series LC resonator circuit, the LC resonator portion of the circuit quickly fills up with energy drawn from the function generator.  Once the LC resonator is full, it becomes a kind of "pumping station" that is synchronous with the function generator waveform such that it effectively disappears.

MileHigh

Offline Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #633 on: January 15, 2014, 03:50:07 AM »
Mags that will get the frequency down no doubt, I'm considering winding some spirals, I've never wound a spiral for a particular reason, I'm thinking I will make them physically as large as is practical for me, and able to take fairly high voltages. Looking forward to all results, it is interesting stuff.

If it wasn't for the high frequencies of the Tesla coil setups and the large inductive field around the coils I would try to measure the voltages and currents in the setup at different states of tune.

I have no choice but to keep my experiments to bench sized arrangements for a while yet.

..

Hey farmhand

Yes. Bench size for me too. ;) I try to maintain things to desktop sizes.

This 3000 turn bifi is about the dimensions of 2 nickles. Wire only. Got 55000 ft for 35 bucks a while back. I cracked open a RS reed relay, 1000 some ohm, and the coil popped out like a can of snakes. Scared me. lol  But that wire must be like in the 50awg compared to the 42. My hair is just a bit thicker than the 42 under a microscope. But man you can produce some strong mag fields with all that resistance and very low currents. ;D Neat to work with.

Mags

Offline MileHigh

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #634 on: January 15, 2014, 05:19:26 AM »
About lowering the resonating frequency:

That's a good strategy because if you work on the bench your "comfort zone" might be between say DC and less than one megahertz.  With those frequencies stray capacitive effects and the low-pass filtering inherent in everything doesn't come into play.  By low "low-pass filtering" I mean your square waves start to get all rounded and mushy.  Likewise at lower frequencies even touching a component with your fingertip will only marginally disturb the circuit so you won't really notice it.  Perhaps for a finger tip touch having no significant effects lower the upper frequency limit to 100 KHz.  You can experiment and check those things for yourselves.

Also, try to sick to capacitor values of one microfarard or larger.  Picofarad caps store pico amounts of energy.  Note a picofarad is one millionth of a microfarad.

You can see when Conrad just brought his hand near the bifilar coil things started changing on his scope display.  That's akin to doing circuit investigations in a kind of mushy and spongy environment.  Most or all of the effects you might be interested in investigating will still take place at lower, more manageable frequencies.

Where of course you do make a change is you use a real capacitor that is always there as opposed to the inter-filar capacitance.  However, just in looking at self-resonance of a coil, there is the voltage sine wave.  So the current sine wave has to be there also.  For a monofilar coil you could envision each end of the floating coil at the voltage peak.  There will be an electric field outside the coil that goes from the top to the bottom almost looking like magnetic field lines.  The monofilar will reach higher absolute voltages at each end relative to the bifilar because the measured capacitance is lower.  For the the bifilar you assume that much more electric field energy is stored in the spaces between adjacent windings.

The extra energy storage capacity in the bifilar and the high voltage capability sound interesting at first glance.  However, you have to remember for both cases, regular and bifilar, the source of the energy to charge the capacitance comes from the inductive energy.  Both the regular and bifilar coil store the same amount of inductive energy.  The source for putting energy into the monofilar or bifilar capacitance is identical.  So what's the high voltage between windings getting you if the source of the energy is the same?

In that sense, the regular and the bifilar self-capacitance act as the "catcher's mitt" to receive the energy thrown at it from the inductance, or inductive energy to be more precise.

In both cases, the capacitive "catcher's mitt" is so tiny that the energy is caught, and the "pressure" in the mitt goes super high for a tiny tiny fraction of a second before the energy is spat back at the inductor.

To mix analogies, you have a humongous elephant hurling a ton of energy.  On receiving end to catch the energy you have too tiny tiny catcher's mitts.   If one mitt is eight picofarads and the other mitt is 37 picofarads, they really look pretty much the same from the perspective of the elephant.  The two capacitances are of the same order of magnitude and the inductive elephant might be five to seven orders of magnitude larger.  So that just about puts the differences in capacitance values in the "don't care" file.   If you are a millionaire, you don't care if you are worth $1,000,008 or $1,000,037.

Beyond that, here is a way to look at the whole situation:  You experiment with real series and parallel LC circuits on your bench using real capacitors at lower frequencies.  Then you know that as the capacitance gets smaller and smaller the LC resonator resonates at a higher and higher frequency.  At the extreme limit you actually remove the capacitor completely and the coil self-resonates.  You intuitively can picture in your mind roughly what would be happening in the coil.  You also know that the frequencies are so high that you are in that mushy and spongy territory where the scope probe capacitance affects the circuit and just waving your hand affects the circuit.  It's kind of the "Twilight Zone" unused region for the operation of the coil.  Sometimes just visualizing it in your head is good enough.

MileHigh

Offline Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #635 on: January 15, 2014, 05:39:49 AM »
A bifilar coil is a parallel LC and a normal coil is a series LC

If we have a cap and charge it to 5v, the cap reads 5v.  2 caps in series, charge with 5v and each cap will have 2.5v. And the capacity goes down as you put more in series. 100 caps in series, charge with 5v and each cap will have .05v.  Same reduction as a normal coil when you add turns. A series LC. ;)


Now put 2 caps in parallel and charge with 5v. Each cap will have 5v. 100 caps, 5v each. That is a bifi coil. More turns, same voltage in each cap as less turns. A parallel LC. ;)

Just in case someone posted otherwise. ;)

Mags

Offline Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #636 on: January 15, 2014, 05:46:44 AM »
Bifi Trivia!!

A bifi coil takes less time to wind than a normal coil because 3000 total turns only takes 1500 revolutions of the bobbin.  ;) ;D

Mags

Offline conradelektro

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #637 on: January 15, 2014, 08:57:12 AM »
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 measured the resonance frequency of a series LC circuit (C = 10 nF), see http://www.overunity.com/13460/teslas-coil-for-electro-magnets/msg383070/#msg383070

The measurement circuit for a series LC tank is from Gyula, see http://www.overunity.com/13460/teslas-coil-for-electro-magnets/msg383065/#msg383065, see also Gyula's explication http://www.overunity.com/13460/teslas-coil-for-electro-magnets/msg383103/#msg383103  The measurement in a series LC tank is less "indicative". (I want to note that Gyula posts good explanations and is often providing expert help, not only in this thread.)

Theory says that parallel and series LC circuit have the same resonance frequency.

The resonance frequency is defined by L = inductance of the coil and C = "external capacitance plus self capacitance". If the "external capacitance" = 0, we have "self resonance" and if the "external capacitance" = large, "self capacitance" becomes negligible.

Also for parallel and series LC circuit: The resonance effect occurs when inductive and capacitive reactances are equal in magnitude.

See http://www.allaboutcircuits.com/vol_2/chpt_6/2.html and http://www.allaboutcircuits.com/vol_2/chpt_6/3.html (the formula for f = frequency is the same in parallel and series LC circuit).

Important facts about parallel LC circuits:

In the parallel configuration, resonance occurs when the complex electrical impedance of the circuit approaches infinity, meaning that the circuit draws no current from the AC power source.

A prallel resonant circuit provides voltage magnification.


Important facts about series LC circuits:

In the series configuration, resonance occurs when the complex electrical impedance of the circuit approaches zero, the result is a short circuit across the AC power source at resonance.

A series resonant circuit provides current magnification
.

(I restated in very short form what MileHigh explained in detail, read his posts, he is a good teacher.)


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.

I am a beginner, but I would say that C = capacitance (the ability to store a charge) is a constant for a given capacitor or between two wires in a coil (independent of Voltage)? But the higher V = Voltage the more Q = charge can be stored in a capacitor. Formula C = Q/V or V*C = Q. So, the resonance frequency will not change with Voltage, but the charges pushed back and forth will be higher if Voltage is higher. See, http://en.wikipedia.org/wiki/Capacitor#Overview.

Greetings, Conrad

Offline MileHigh

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #638 on: January 15, 2014, 09:52:05 AM »
Some great clips from Itsu:

Pick-up coil for a pulse motor configured in parallel resonance:

http://www.youtube.com/watch?v=syxL4f2OsPg
http://www.youtube.com/watch?v=yNtnLAVk9Og

Pick-up coil for a pulse motor configured in serial resonance:

http://www.youtube.com/watch?v=K-avee5Z1oU

Offline conradelektro

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #639 on: January 15, 2014, 10:00:13 AM »
@MileHigh: Again, great explanations, thank you. The nebula in front of my eyes when looking at LC circuits and coils is lifting.

So, I will wind two helical coils with "many turns and many layers of turns" (one bifilar the other monofilar) to bring my tests into the 100 KHz region.

The planned coil parameters:

- core diameter 10 mm (interchangeable: air core, fitting Ferrite core and bundle of soft wire sticks)

- length of coil 30 mm

- outer diameter of coil 40 mm

- 31 AWG wire (wire diameter 0.22 mm)


I would also say to Farmhand and all other pan cake coil builders to wind a big pan cake coil with many turns for the same reason.

My two pan cake coils are a bit small and have too few wires and therefore introduced problems when testing caused by the MHz frequencies involved (the 1 pF decoupling capacitor for my scope probe became an important issue which was expertly solved by Gyula).

It is much easier to wind a pan cake coil with thick wire, but it will then have relatively few turns. It takes some craftsmanship to wind a pan cake coil and it needs a support plate (may be Plexiglass or some other plastic sheet, may be a very dry wood board).

For measurements please see my posts:

http://www.overunity.com/13460/teslas-coil-for-electro-magnets/msg383043/#msg383043
http://www.overunity.com/13460/teslas-coil-for-electro-magnets/msg383045/#msg383045
http://www.overunity.com/13460/teslas-coil-for-electro-magnets/msg383070/#msg383070
http://www.overunity.com/13460/teslas-coil-for-electro-magnets/msg383084/#msg383084
http://www.overunity.com/13460/teslas-coil-for-electro-magnets/msg382906/#msg382906

and videos at http://www.youtube.com/user/conradelektro/videos

Good calculators:

http://www.1728.org/resfreq.htm
http://daycounter.com/Articles/How-To-Measure-Inductance.phtml
http://www.qsl.net/in3otd/inductors.html

This kind of concludes my measurements with my two pan cake coils. For the time being I move on to helical coils. But if some tangible and understandable claim concerning pan cake coils materialises I am ready to go back.

Greetings, Conrad

Offline conradelektro

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #640 on: January 15, 2014, 10:12:42 AM »
Some great clips from Itsu:

Pick-up coil for a pulse motor configured in parallel resonance:

http://www.youtube.com/watch?v=syxL4f2OsPg
http://www.youtube.com/watch?v=yNtnLAVk9Og

Pick-up coil for a pulse motor configured in serial resonance:

http://www.youtube.com/watch?v=K-avee5Z1oU

@MileHigh:

Would it make sense if I wind the bifilar coil with 6 wires like itsu (see the attached drawing)?

Itsu video: http://www.youtube.com/watch?v=syxL4f2OsPg minute 03:02

Greetings, Conrad

Offline MileHigh

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #641 on: January 15, 2014, 02:22:47 PM »
Hi Conrad,

You don't need to use 6 wires.

MileHigh

Offline synchro1

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #642 on: January 15, 2014, 05:10:04 PM »
Youtube quote from Dr. Steven Jones:

"Note that I replace the conducting disk with a bifilar pancake coil (BPC) wound with coax. Charge from the coil is collected through a Schottky diode on a 47 uF capacitor which held at zero mV for an extended time prior to the experiment"

Look at the identical "Synchro Coil" circuit Dr. Steven Jones is using, Schottky diode and capacitor in series with a bifilar coil! Take special note of the "ELECTROLYTIC CAPACITOR" with the testing probes attached! Ask yourselves what kind of results one could expect if someone rudely barged in and replaced his diode and capacitor with a couple of resistors? This experiment is practically identical to the "Synchro coil" except that the "Synchro coil" works from rotor excited magnet core flux, instead of the bipolar disk agitation!

Check out his video on the FARADAY'S PARADOX REVISITED BPC (Bifilar Pancake Coil):

http://www.youtube.com/watch?v=I3hXYSKxsX0

It should be clear that positioning the "Synchro Coil" in the flutter zone would cause exactly the same kind of magnetic fluctuation Dr. Jones induces in his BPC with his spinning disk! Dr. Steven Jones defies Faraday's paradox with this experiment, just like the "Synchro Coil" does. Take note of the importance Dr. Steven Jones attributes to the positioning of the magnetized disk in his video!

Milehigh and Conradelektro blatently kiboshed my "Synchro coil" test, went on to run DC current through a PMH coil then "curled their chimp lips back" with a "no locking effect" magic claim grin!

My worst paranoia is that those two staged that "Synchro Coil" failure to develop the coil in secret for commercial profit!
« Last Edit: January 15, 2014, 07:35:52 PM by synchro1 »

Offline Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #643 on: January 15, 2014, 07:10:12 PM »
I'm considering winding some spirals, I've never wound a spiral for a particular reason, I'm thinking I will make them physically as large as is practical for me, and able to take fairly high voltages. Looking forward to all results, it is interesting stuff.



When i was studying car audio, and audio in general, an interesting thing I found along the way may apply here.

When you input a freq into a speaker, that has an audio wavelength that is shorter than the diameter of the speaker will tend to 'beam' from the cone surface. Now the wave length Im talking about is the distance in air that a single cycle of the wave is. Like if you have 2 tweeters in front of you at a distance, then start to bring one of the tweeters closer to you say at about 10khz there will be a distance as the tweeter gets closer where the 2 waves from the tweeters will be 180 out of phase and you wont here it any longer. Then move the tweeter closer to you, just double the first distance and you are back in phase. Like 3khz is around 3in or 6in to be out of phase if I remember correctly.

So I wonder if a beaming effect could be produced with a pancake coil.  Or even if it would be useful. I suppose greater distance to a receiver would be an advantage. Would probably have to be huge in diameter for even very high freq.  Would have to look that up.

Just a thought I had at work before lunch. Dont know if it has any relevance.

Mags

Offline tim123

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #644 on: January 15, 2014, 08:04:37 PM »
Check out his video on the FARADAY'S PARADOX REVISITED BPC (Bifilar Pancake Coil):
http://www.youtube.com/watch?v=I3hXYSKxsX0
...
My worst paranoia is that those two staged that "Synchro Coil" failure to develop the coil in secret for commercial profit!

Synchro, mate...

 1) That vid above by Stephen Jones, has to be one of the worst conducted experiments I've ever seen... It's terrible.

 2) The experiments you keep ranting about are *so easy to do yourself* - that your ranting is ridiculous.

 3) Your attitude towards Conrad & MH is out-of-order!

Just do the damn experiment yourself. For goodness sake!

I'm beginning to be quite irked by people who are not prepared to do their own !$%&# experiments!