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Author Topic: Tesla's "COIL FOR ELECTRO-MAGNETS".  (Read 429315 times)

Offline synchro1

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #690 on: January 18, 2014, 04:02:14 PM »
Well I could do the test with my own small coils , but I see no real point, the coils both have the same DC resistance and both have the same inductance and cores (iron powder rods), both coils will see the same current and create the same magnetic field. I'm reluctant to waste another night dong what others have already shown that I agree with.

Which is that when a continuous DC current is sustained through the two different coils they will behave the same, should be as exactly the same as is possible considering build tolerances.

I'm interested to see if there are any efficiency differences between some higher inductance, fairly high resistance (relatively)  coils of both monofilar and bifilar coils when excited with a frequency and loaded in various ways to various levels. One way to load a spiral AC electromagnet would be with a steel plate. A way to load a regular solenoid electromagnet might be to use it as a mechanical oscillator drive or something.

Of course my use of the general  term "resonance" is wrong when talking of simply tuning a systems L or C to get maximum power through a load on a "tank".

Tesla did not use the term resonance in the patent and I can accept I used the wrong term, if resonance played a major part he would have said so in the patent as he was not afraid to use the term. I will change my language in future to say simply tune the circuit.

Cheers

 


The serial bifilar coil generates a quarter million times the potential between the windings as the monofilar. How can you overlook this overwhelming difference? All you refer to is the D.C. resistance and inductance. What about the enormous difference in Hi-Voltage potential? I drummed this in relentlessly. Pay attention! The Tesla serial Pancake coil was pateneted as an iron ferrite MAGNETIZER COIL! The coil magically transmutes iron into a permanent magnet!

Now, if you plan to do the experiment, why not take a trip to the hardware store and buy the 16 penny nail that "Tesla-Coil-Builder" calls for, and use the correct gauge magnet wire stipulated by him. You're going too far afield by improvising materials. This grows very complex with the core reluctance and number of wraps etc. If you do the test like he instructs, you'll get the correct results. A zinc or nickel or chome plated bolt won't magnetize like a soft iron nail. All you'll be left with is the coil's field strength like in Magluvin's test.

Offline synchro1

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #691 on: January 18, 2014, 04:10:16 PM »
Here's a very simple experiment for someone like Magluvin who just wrapped a few spiral coils. I'm ill equipped to perform this one.

Place the serial bifilar pancake on two different metal plates, one at a time, one iron and another aluminum perhaps or any two different metal plates and check the SB pancake coil's inductance in Micro Henries. Then repeat the test with the monifilar. The serial bifilar's inductance is supposed to change due to the high potential between the wraps and the difference in conductivity of the metal plate in adjacency. Repeat the experiment with the monofilar and compare any change in inductance. This is testing the serial bifilar pancake as a magnetizer sensor! The serial bifilar pancake coil is very sensitive compared to the monofilar! Remember, it spontaneously generates 250,000 times the hi-voltage electrical potential between the windings than the single wrap! This power doesn't count for nothing!  This is where to find the MAGIC!

Offline conradelektro

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #692 on: January 18, 2014, 07:08:43 PM »
@Farmhand and the experts:

I just watched Farmhand's video https://www.youtube.com/watch?v=c6nP1HekThc (ring transformer) and it reminds me of an experiment I did last Thursday with my large bifilar Bedini coil (which I posted here http://www.overunity.com/13460/teslas-coil-for-electro-magnets/msg383363/#msg383363).

MileHigh mentioned that I can use only one wire (of the large bifilar coil) to have a comparable monofilar coil (with 1/4 of the inductance). I measured the inductance of each of the two wires, see this post http://www.overunity.com/13460/teslas-coil-for-electro-magnets/msg383374/#msg383374 . The inductance of one wire is indeed 1/4 of the inductance of the wires in series (measured with my LCR meter).

So far so good. Then I tried to measure the self resonance of one wire with an exciter coil wound around the bifilar coil. It is the same exciter coil (4 turns of white wire) I used to measure the self resonance of the wires in series (see the photo attached to the first post mentioned above, the exciter coil was simply left in place).

And, I could not measure the self resonance of just one wire with the exciter coil. And, I could not measure the self resonance of the two wires connected in parallel with the exciter coil. (Coil had no core, air core.)

I tried a lot, but no success. It seems that the exciter coil can only "excite" the big coil if and when the two wires are connected in series.


Then I had to stop experimenting (no more free time) and can only do more tests on Monday (I am not at home ).

I write it, because farmhand showed a similar strange measurement over one wire of a bifilar winding and over the wires of a bifilar winding in parallel (on his big ring core in his video).

Greetings, Conrad

Offline MileHigh

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #693 on: January 18, 2014, 07:46:52 PM »
Conrad:

Perhaps the self-capacitance is so low that the self-resonant frequency is much higher than you were expecting?

MileHigh

Offline MileHigh

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #694 on: January 18, 2014, 07:53:22 PM »
Quote
Now, if you plan to do the experiment, why not take a trip to the hardware store and buy the 16 penny nail that "Tesla-Coil-Builder" calls for, and use the correct gauge magnet wire stipulated by him. You're going too far afield by improvising materials. This grows very complex with the core reluctance and number of wraps etc. If you do the test like he instructs, you'll get the correct results.

These are classic "secret sauce" arguments.  It has to be the right wire, etc.  Those are to be judged on a case-by-case basis.  In the majority of cases the "secret sauce" arguments aren't true.  They are a classic technique used by con artists also.  I am not implying at all that Synchro1 is a con artist because he is clearly not.

Offline conradelektro

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #695 on: January 18, 2014, 08:20:08 PM »
Conrad:

Perhaps the self-capacitance is so low that the self-resonant frequency is much higher than you were expecting?

MileHigh

@MileHigh:

The self resonance frequency of the bifilar coil (the two wires in series) is 4600 Hz (air core) which gives a self capacitance of 7 nF. How low could it be for one wire? Anyway I tried up to 20 Mhz (the limit of my function generator).

I will try to get resonance with capacitors (LC circuit) on Monday (10 µF, 1 µF and 0.22 µF) and also try for self resonance again. It can well be that I did something stupid, it was late.

The most puzzling thing is that it did not work with the wires in parallel? The two wires have different diameters, one is thinner than the other.

Greetings, Conrad

Offline Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #696 on: January 18, 2014, 08:39:38 PM »
@MileHigh:

The self resonance frequency of the bifilar coil (the two wires in series) is 4600 Hz (air core) which gives a self capacitance of 7 nF. How low could it be for one wire? Anyway I tried up to 20 Mhz (the limit of my function generator).

I will try to get resonance with capacitors (LC circuit) on Monday (10 µF, 1 µF and 0.22 µF) and also try for self resonance again. It can well be that I did something stupid, it was late.

The most puzzling thing is that it did not work with the wires in parallel? The two wires have different diameters, one is thinner than the other.

Greetings, Conrad



In my earlier posts,  a 2 turn normal coil has the same capacitance as a 2 turn bifi. ;)

Every time you add a turn to each coil, the effective capacitance of the normal coil will go down and the bifi will go up. ;)   So the other coils you were testing had as many turns that would make the normal coil capacitance somewhat lower, and the bifi somewhat higher. When you get into a lot of turns, the spread gets wider. ;)

The info I give is not just nonsensical ramblings. ::) ;D

Mags

Offline Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #697 on: January 18, 2014, 08:55:34 PM »

 If you do the test like he instructs, you'll get the correct results. A zinc or nickel or chome plated bolt won't magnetize like a soft iron nail. All you'll be left with is the coil's field strength like in Magluvin's test.

Actually, I used  non plated 16 penny nails. We have a guy doing construction at my work. I did do a thin wrap of teflon tape, as the ribbed burrs close to the head of the nail may have scraped the insulation of the wire. I believe for that test to be evident, the coils need many more wraps than described in the article, especially to use a D cell. The author of that site should make changes to that article. Its the right idea, just the wrong ingredients. Sure it may work 'better' with high voltage, but the article doesnt express that.

Mags

Offline MileHigh

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #698 on: January 18, 2014, 09:06:33 PM »
Conrad:

Assuming the frequency is too high, there is a way of making inferences about the self capacitance using different values of capacitor.   Perhaps if you start with a one nanofarad capacitor and measured the resonant frequency and worked your way back from there you would see a trend line in the frequency.  As you reduce the capacitance values what happens to the frequency?  Does it start to go much higher than you have seen in other similar tests?

Of course it's noted that the capacitance is always the self-capacitance plus the capacitor capacitance plus the probe capacitance.  I am not factoring in frequency effects here but we know they come into play when you are in high frequency territory.

The geometry is telling you that the capacitance has to decrease.  Now the distance between adjacent wires is very large because there is an unused wire between each active wire in the coil.  If you look up the formula for the capacitance between two plates of metal, you will find that it's inversely proportional to the distance between the plates.  So the difference in capacitance between two wires that are 0.1 mm apart vs 2 mm apart is very large.  It's possible that the self-capacitance is now so low that it's very hard to measure, and also very hard to observe any effects from it.

MileHigh

Offline gyulasun

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #699 on: January 18, 2014, 09:28:36 PM »

I place the critical minimum frequency for DLE (Delayed Lenz Effect) for a diametric magnet spinner at twenty five thousand RPM. I measured my spinner speed with a piece of reflective tape attached and a laser tachometer.  Itsu apparently lowered the CMF for DLE to a veritable 18,000 RPM with his resonant output coil. This amounts to an achievement, but I think Conradelektro will encounter slow down at 10,000 RPM.

I check my input with a digital ampmeter.

Synchro1:

Why do you attribute to Itsu things he obviously did not do?  He did not lower the CMF for DLE to 18,000 rpm with his resonant output coil! In his parallel resonance video the highest frequency from his generator coil output was 206 Hz (this is 12,360 rpm and this latter rpm  occured when he shorted the output), no any higher rpm was demonstrated.  How can you claim he lowered it to 18,000 rpm??   (For the other members: Itsu's video is here:  http://www.youtube.com/watch?v=syxL4f2OsPg )


quoting from your post to Farmhand:

The serial bifilar coil generates a quarter million times the potential between the windings as the monofilar. How can you overlook this overwhelming difference? All you refer to is the D.C. resistance and inductance. What about the enormous difference in Hi-Voltage potential? I drummed this in relentlessly. Pay attention! The Tesla serial Pancake coil was pateneted as an iron ferrite MAGNETIZER COIL! The coil magically transmutes iron into a permanent magnet!

What you wrote above proves that you try to make out any possible "explanation" which seems to prove the superior performance of your "synchro coil". Here is a link to the Tesla patent, very easy to quote the original text because of the neat style of the html page: http://www.teslauniverse.com/nikola-tesla-patents-512,340-coil-for-electro-magnets  and please quote Tesla's text where he wrote about any iron ferrite magnetizer coil or he wrote about turning any core into a permanent magnet!

The other thing is you claim a COP of 2 for the series bifi coil versus the monofilar coil because in your paper clip tests you found your electromagnet with the series bifi coil lifted up 2 pieces of paperclips  while the monofilar electromagnet lifted up only one paperclip: Please explain that in those tests where or how was the quarter million times higher potential present in the series bifi coil when you used a 12V DC battery source for the tests? (You wrote earlier to my question that you used a 12V battery.)

Gyula

Offline synchro1

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #700 on: January 18, 2014, 09:30:55 PM »
Actually, I used  non plated 16 penny nails. We have a guy doing construction at my work. I did do a thin wrap of teflon tape, as the ribbed burrs close to the head of the nail may have scraped the insulation of the wire. I believe for that test to be evident, the coils need many more wraps than described in the article, especially to use a D cell. The author of that site should make changes to that article. Its the right idea, just the wrong ingredients. Sure it may work 'better' with high voltage, but the article doesnt express that.

Mags


Let me add that the series bifilar pancake or solenoid coil has to be CHARGED initially to reach it's full potential. This is done simply by snapping a good spark across the leads. Attempting to charge a single coil is useless. I used a depleted Bedini charge battery that was originally 12 volts, bled down to "D" cell voltage. Too much power will fry those tiny coils in no time! Once fully charged, a small amount of D.C. current will produce the extra magnetic strength in the iron core. High reluctance ferrite with low remanence won't magnetize like soft iron. Farmhand said he had some ferrite lying around. It probably won't work because it looses it's magnetic strength too quickly. Coercivity is another dynamic involving the amount of current required to reverse the magnetic charge. Iron has a low enough coercivity to release the junk on a scrap yard pancake electromagnet. You can get the nail coil to drop the load of paper clips, by inducing a reverse charge too. Higher coercivity alloys like Alnico will retain the attraction.

Offline Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #701 on: January 18, 2014, 09:52:06 PM »
Say we had a BIG coil. 100H coil. 

At 100h  with a cap across it of 70.3nf we get a resonance of 60hz

100H  6.3nf 200hz

100h  100pf  1.6khz

100h  11pf   4.7 khz

Now just imagine all that wire to make that big coil, it definitely isnt going to ring at 5 or 10khz on its own. Not even 100khz

100h  1.1pf  15khz

So the Big 100h coil has a virtually non existent capacitance.  So what would we imagine the capacitance of a bifi coil of the same wire and turns? 

Not saying we need to make 100h coils. It was just an example for understanding. ;)

Mags

Offline synchro1

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #702 on: January 18, 2014, 09:57:17 PM »

@Gyula,


Quote from Gyula:

"Why do you attribute to Itsu things he obviously did not do?  He did not lower the CMF for DLE to 18,000 rpm with his resonant output coil! In his parallel resonance video the highest frequency from his generator coil output was 206 Hz (this is 12,360 rpm and this latter rpm  occured when he shorted the output), no any higher rpm was demonstrated.  How can you claim he lowered it to 18,000 rpm??   (For the other members: Itsu's video is here: http://www.youtube.com/watch?v=syxL4f2OsPg )"


Look, Itsu's running four magnets at 150 hertz RPM. That's 9,000 RPM equal to 18,000 RPM for the diametric. Now your raising his speed to 206 Hertz which would yield an equivilant of 24,720 for a diametric frequency. Then you ask me how come I'm attributing a rate of 18,000 RPM's to Itsu!


I maintained the critical minimum frequency for a diametric spinner to catch DLE was 25,000 RPM's. Itsu caught it at 9,000 RPM's which would equate to 18,000 RPM's for a diametric magnet, 7,000 RPM's less then where I get it with my spiral output coil and sphere spinner. JLN's spinning at 30,000 RPM with his diametric in his test.

Offline MileHigh

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #703 on: January 18, 2014, 09:58:13 PM »
Gyula:

Thank you for puling up the YouTube clip with the AM band resonator.  The one I saw was a commercial version, probably manufactured in the late 1960s.  It must be in the "plastic mould graveyard."

Going back to the self-capacitance issue, there is an exercise that anyone can do as an exploration into the whys and wherefores.  Try to estimate the capacitance between to adjacent loops in one of your coils.  You don't have parallel plates.  So you make a reasonable estimate as to how much a long length of wire of a given diameter translates into an equivalent long rectangular metal plate.  What is the approximate equivalent distance between the plates?  Let's keep it simple and assume the relative permittivity of the plastic insulation is one.  That can also be looked up.

So with a few reasonable judgement calls and a bit of punching the numbers in a formula you can make an estimate of the capacitance per pair of adjacent turns of wire in your coil.  Then you can make a quasi estimate the self-capacitance for the entire coil.  Then you can compare the two values, estimated and measured.  Sometimes the estimated value and the measured value for some kind of system are consistently different by some constant or near constant value.  That gives you a "compensation factor" for estimated capacitance so that you can compensate and accurately estimate the actual self capacitance.

There is another way to approach this issue.  I still will pitch light gauge speaker wire.  The two conductors are very close to each other.  You could just put a capacitance meter on the the isolated wire pair and measure the capacitance of the entire spool.  (Note: With that data you could work your way back to approximating the dimensions and separation distance for the equivalent long and thin rectangular plate capacitor.  Once you have the equivalent model for the two adjacent wire loops as a long thin rectangular plate capacitor, you just punch in the numbers and you are done.  So it's also a way of estimating the equivalent long and thin rectangular plate capacitor.)

Then connect up the spool of speaker wire in a series bifilar configuration and measure the self capacitance from the resonant frequency.  Again the question is:  Is there any corelation between the measured isolated wire capacitance and the measured self-resonant capacitance?  Is there a possible compensation factor that you can determine so that you can make a "weighted" or "true" estimate?

MileHigh

Offline Magluvin

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Re: Tesla's "COIL FOR ELECTRO-MAGNETS".
« Reply #704 on: January 18, 2014, 10:14:36 PM »

Let me add that the series bifilar pancake or solenoid coil has to be CHARGED initially to reach it's full potential. This is done simply by snapping a good spark across the leads. Attempting to charge a single coil is useless. I used a depleted Bedini charge battery that was originally 12 volts, bled down to "D" cell voltage. Too much power will fry those tiny coils in no time! Once fully charged, a small amount of D.C. current will produce the extra magnetic strength in the iron core. High reluctance ferrite with low remanence won't magnetize like soft iron. Farmhand said he had some ferrite lying around. It probably won't work because it looses it's magnetic strength too quickly. Coercivity is another dynamic involving the amount of current required to reverse the magnetic charge. Iron has a low enough coercivity to release the junk on a scrap yard pancake electromagnet. You can get the nail coil to drop the load of paper clips, by inducing a reverse charge too. Higher coercivity alloys like Alnico will retain the attraction.

Like I said earlier, testing the 2 coils on a Leedskalnin holder would give definitive data in my opinion. If done properly one could truly measure if there is more field and how much. Part of my tests will do measurements with linear hall sensors.

Still working on the coil winding setup. I only want to do it once without wire breakage. >:( ;D

Mags