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Author Topic: The bifilar pancake coil at its resonant frequency  (Read 563333 times)

MileHigh

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Re: The bifilar pancake coil at its resonant frequency
« Reply #60 on: March 25, 2017, 12:24:40 PM »
Nelson:

The central issue is what is the reason for taking a bifilar pancake coil and exciting it at its self-resonant frequency?  Why do this?  What are you trying to accomplish?  What practical applications are there for this?  It's fun to "play" but what is the point behind the playing?  Those are the types of questions that are avoided and never posed and never answered by many experimenters.

Here is another set of questions:  Why a bifilar pancake coil?  Why not a regular pancake coil?  Does making it bifilar really do anything more than let the experimenter proclaim that there is a stronger electric field between the wires?  So what?  What about a solenoid bifilar coil, or even just an ordinary solenoid coil?  Both of the solenoid coils can be excited at their self-resonant frequencies also.   So there are four types of coils that I just mentioned.  What do you want to accomplish with the coil and what can you say about each of the four types of coils relative to what you want to accomplish?  We are talking about doing something practical with the coil.  I get the sense that these are difficult questions for many experimenters to answer.

A bifilar pancake coil, a similar pancake coil, and a bifilar solenoid coils and a regular solenoid coil with approximately the same amount of inductance as the pancake coils will all have different self-resonant frequencies and we know that for the two bifilar cases the self-resonant frequencies will be lower.  So what, what can you do with this information beyond making a frequency measurement and an observation?

Suppose you want your coil to act as a generic inductor in an electronics circuit.  Which of the four types of coil would be the best choice for this?   The answer is the regular solenoid coil.  The regular solenoid coil will meet the design goal with less wire and less resistance and less unwanted self-capacitance and have a higher working frequency bandwidth.

Suppose you want to make an air-core transformer.  Which of the four types of coil would be the best choice for this?  One more time, the answer is the regular solenoid coil.  The regular solenoid coil will meet the design goal with a more efficient coupling for power transfer, less wire used and less resistance and less unwanted self-capacitance and have a higher working frequency bandwidth.

When you look at a datasheet for a small coil that you might put onto a PCB they give you the maximum operating frequency for the coil and the self-resonant frequency for the coil.  Electronics designers avoid feeding the coil signals that go higher in frequency than the maximum operating frequency because above the maximum operating frequency you are approaching the self-resonant frequency for the coil and at those high frequencies the coil fails to function as a coil anymore.  As a general rule of thumb, electronics designers avoid the self-resonant frequencies of coils in their circuits.

Quote
A bifilar pancake coil is capable of holding more charge than a single wound coil and that is known .
When this coils are operated at resonance, the distributed capacitance on the bifilar  overcome the counter electromotive force that normal is find in conventional coils.

Not really, because the typical model for self-resonance of a coil is a parallel LC circuit.  A parallel LC circuit when connected in series with a load acts as an infinite impedance at the self-resonant frequency.  That means that the coil is acting like a 100% counter electromotive force device that opposes the excitation frequency with an equal and opposite voltage.

I will just repeat to you again:  I am telling you with 100% certainty that it is a major mistake to use a square wave when trying to find the self-resonant frequency of a coil.  What you should be doing is trying to understand for yourself why I am saying that.  Rejecting what I am telling you is the wrong course of action.

Quote
It's important for experimenters to realize that they simple can not assume something only because persons like you are not able to view more deeply some of aspects of bifilar pancake coil that are denied .
But persons like you that use the sentence  "carved in stone" to justify something without testing ,for sure will take their stubbornness to their grave stone too.

I probably just raised more questions about bifilar pancake coils and three other variations that you may never have even considered.  This is to get you and your peers to start critically thinking and examining all of the issues.  Chances are that I am viewing this issue more deeply than you have ever done before, and I am not even a hard-core electronics guy.  Sometimes things really are carved in stone.

I am challenging you and your peers to improve your wisdom.  If I was in your shoes I would test four coils, a pancake bifilar, a regular pancake coil, a bifilar solenoid coil, and a regular solenoid coil.  I would define some objectives, develop some test procedures, and arrive at some conclusions.  The general conclusion will be that the regular solenoid coil performs the best and offers the most inductance per unit of wire length and therefore has the least amount of resistive losses.  It also has the least unwanted self-capacitance that reduces the working bandwidth of the coil.  If you think a series bifilar coil is something special then you have to make tests and demonstrate what makes it special and why.

MileHigh

gyulasun

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Re: The bifilar pancake coil at its resonant frequency
« Reply #61 on: March 25, 2017, 02:07:16 PM »
Gyula,

I just wound a single wire coil of the same gauge on an identical bobbin and measured the Ohms and Inductance. The test results show that you're right as regards the air core coils. I could only fit 4 Ohms worth of wire on the bobbin. The inductance was 4.3 mh. The serial bifilar at 5 Ohms delivered  5.81 mh. The ratio is pretty close at 1.162 mh per Ohm for the serial bifilar and 1.05 mh per Ohm for the single wire coil. There's clearly no where near the 100% difference Gotoluc measures with his ferrite toroid coils. nor the twice the magnetic strength my iron nail core serial bifilar demonstrated. The sloppy lash wrap of my single wire coil accounts for the slightly lower inductance to Ohms ratio. I concede that TK's measurements are correct and that his meter is functional.

It appears the ferrite core plays a critical role in the doubling of inductance with this Tesla bifilar connection. Maybe TK can run a ferrite core into his bore holes and make comparison measurements for us to help.

synchro1,

Very good you built the coil with single wire and obviously the fact that you did not have the same length of wire and had 4 Ohm DC resistance (instead of 5 Ohms) explains the 4.3mH inductance instead of the 5.81mH, no problem. 

You refer to Gotoluc's video, back then he used those toroidal coils in his circuit shown here:
http://overunity.com/8892/self-running-coil/msg233254/#msg233254 

so his toroidal core is not wound bifilarly but with one winding (in 5 layers) is wound on one half of the core and the other winding (also in 5 layers) is wound on the other half of the core, ok?
Such winding style is used for instance in so called common mode choke coils, see here one with single layer windings placed on the right and on the left hand side of the core:
http://wcmagnetics.com/product/50-amp-toroidal-common-mode-choke-507-series/

This type of winding can have double the inductance when the two windings are correctly connected in series (i.e. not to work as common mode choke) versus the same amount of wire (the two half windings have together) wound onto the same toroidal core in the normal way. However, we are now discussing Tesla style bifilar coils, not the winding style Luc used.

IT is not the ferrite core which playes the critical role but the winding style and position of the windings with respect to each other on the core (mutual inductance) that counts in the resulting L inductance of the series windings.

Gyula 

Dog-One

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Re: The bifilar pancake coil at its resonant frequency
« Reply #62 on: March 25, 2017, 02:22:04 PM »
Quote from: MileHigh or MileDeep
The regular solenoid coil will meet the design goal with a more efficient coupling for power transfer, less wire used and less resistance and less unwanted self-capacitance and have a higher working frequency bandwidth.

What if I'm not at all interested in power transfer?  What if I'm after something completely different?

Can you answer me what it is I could possibly be looking for?

If you have no clue, maybe it's time to cease and desist.


I'm quite certain Nelson knows what I'm referring to.   ;)

synchro1

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Re: The bifilar pancake coil at its resonant frequency
« Reply #63 on: March 25, 2017, 02:27:19 PM »
Quote from Milehigh:

"The central issue is what is the reason for taking a bifilar pancake coil and exciting it at its self-resonant frequency"?

Tesla used the bifilar pancake to transmit and recieve wireless power which is less efficient to do with the bifilar solenoid or the single wire pancake.

synchro1

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Re: The bifilar pancake coil at its resonant frequency
« Reply #64 on: March 25, 2017, 02:35:34 PM »
synchro1,

Very good you built the coil with single wire and obviously the fact that you did not have the same length of wire and had 4 Ohm DC resistance (instead of 5 Ohms) explains the 4.3mH inductance instead of the 5.81mH, no problem. 

You refer to Gotoluc's video, back then he used those toroidal coils in his circuit shown here:
http://overunity.com/8892/self-running-coil/msg233254/#msg233254 

so his toroidal core is not wound bifilarly but with one winding (in 5 layers) is wound on one half of the core and the other winding (also in 5 layers) is wound on the other half of the core, ok?
Such winding style is used for instance in so called common mode choke coils, see here one with single layer windings placed on the right and on the left hand side of the core:
http://wcmagnetics.com/product/50-amp-toroidal-common-mode-choke-507-series/

This type of winding can have double the inductance when the two windings are correctly connected in series (i.e. not to work as common mode choke) versus the same amount of wire (the two half windings have together) wound onto the same toroidal core in the normal way. However, we are now discussing Tesla style bifilar coils, not the winding style Luc used.

IT is not the ferrite core which playes the critical role but the winding style and position of the windings with respect to each other on the core (mutual inductance) that counts in the resulting L inductance of the series windings.

Gyula

How would you explain the doubling of magnetic strength in my "Tesla Coil Builder" bifilar vs. single wire electro-magnet test with the trombone paper clips?

nelsonrochaa

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Re: The bifilar pancake coil at its resonant frequency
« Reply #65 on: March 25, 2017, 02:59:56 PM »
Hi MH , you talk a lot make me write a lot too :) and English is my third language so not easy answering to last big "testament".


“The central issue is what is the reason for taking a bifilar pancake coil and exciting it at its self-resonant frequency?Why do this? What are you trying to accomplish? What practical applications are there for this? It's fun to "play" but what is the point behind the playing? Those are the types of questions that are avoided and never posed and never answered by many experimenters. “

What i try accomplish have nothing to do with topic , i’m not talk about my own work,  but about  the topic that Evostars open .

“Here is another set of questions: Why a bifilar pancake coil? Why not a regular pancake coil? Does making it bifilar really do anything more than let the experimenter proclaim that there is a stronger electric field between the wires?”

Myself already answer about that point but i answer again :
Self induction of coil will be zero.  In a pancake bifilar coil  the magnetic field of one of winding is  equal and opposite to that created by the other wind canceling their self inductance.


“Suppose you want to make an air-core transformer. Which of the four types of coil would be the best choice for this? One more time, the answer is the regular solenoid coil. The regular solenoid coil will meet the design goal with a more efficient coupling for power transfer, less wire used and less resistance and less unwanted self-capacitance and have a higher working frequency bandwidth.”

Sorry but i don’t agree about that point that regular solenoid have a more efficient coupling in power transfer , and even with less wire , resistance and self-capacitance . You should test before talk otherwise you are just talking something that someone write and you assume that true is unbreakable .

“I will just repeat to you again: I am telling you with 100% certainty that it is a major mistake to use a square wave when trying to find the self-resonant frequency of a coil. What you should be doing is trying to understand for yourself why I am saying that. Rejecting what I am telling you is the wrong course of action.”

Sure i understand , that point and i did not say that is the best option or not , just tell that is possible with a square wave find the self -resonant frequency of the coil in same way.
About i go in wrong course of action …  Will it? :)

“I probably just raised more questions about bifilar pancake coils and three other variations that you may never have even considered.This is to get you and your peers to start critically thinking and examining all of the issues. Chances are that I am viewing this issue more deeply than you have ever done before, and I am not even a hard-core electronics guy. Sometimes things really are carved in stone.”

Now you are start acting a bit more weird  … what peers are you referring ?  About you say that are viewing more deeply than me , for sure not , go to bench and test it is easy and after you can show us .
OHHH i forget ! You don’t need you already answer that in last email your “peers” already did that no chance of that “peers” fail.

“I am challenging you and your peers to improve your wisdom”
I’m improve everyday , even with less correct information provide by other , and i do not feel like I knew everything, my learning window is still open .


“The general conclusion will be that the regular solenoid coil performs the best and offers the most inductance per unit of wire length and therefore has the least amount of resistive losses. It also has the least unwanted self-capacitance that reduces the working bandwidth of the coil”

Is your conclusion and i accepted that , but not agree .

“If you think a series bifilar coil is something special then you have to make tests and demonstrate what makes it special and why.”

I don't think that coil is special , i guarantee that is real special because i already test it, otherwise why should i use in my  work ? . Should i demonstrate to whom ?
To you ?
Just put you hands at work and see by yourself , otherwise you are just throw away words like a parrot nothing more . What is the difficulty to you in test it ?  Is you that are try convince me and my “peers” about your point of view , go forward show something to us ! To me since i’m a member of this forum it will a pleasure see you make something more “palpable” then simple talk .

Have a nice day MH



synchro1

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Re: The bifilar pancake coil at its resonant frequency
« Reply #66 on: March 25, 2017, 03:47:40 PM »
Impulse magnetization, "Lazy Eight OU":

https://www.youtube.com/watch?v=YeJ5wHBpaf4&t=49s

synchro1

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Re: The bifilar pancake coil at its resonant frequency
« Reply #67 on: March 25, 2017, 05:03:12 PM »
I got shicked 18 months ago when I commented on Skycollection's Conradelectro P/I P/O test. Jorge determined that his six Hexafilar LED's, not connected by anything more than wireless induction between his Tesla serial bifilar pancake coils, sustained amperage but suffered a voltage drop instead while the LED's maintained their luminosity. The reverse of conventional grid usage where they feed amperage into the system, and voltage remains constant. Suppose we have to feed lights in parallel down a 10 miles long wire. Ohms law of inverse resistance to voltage points to the advantage of stepping voltage up to feed the farthest lights, rather then generating amperage.     

evostars

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Re: The bifilar pancake coil at its resonant frequency
« Reply #68 on: March 25, 2017, 05:17:13 PM »
https://www.youtube.com/watch?v=uiLgM3EkQBE
With this bifilar pancake coil i can charge the 12 v battery without magnet rotor, can you describe this experiment...?
Nice experiment, and a nice stack of pancake coils!

I've been wondering about charging a battery with the dielectric resonant voltage. Thanks for showing that it works.

Have you noticed a difference, in how the coil is connected? I noticed, north is stronger. Why do you not use 2 diodes, to create a plus and minus from the resonant sine wave?

really cool to hear it buzzing with the magnet on top. I hear my coils buzzing sometimes, when I load them unbalanced.

synchro1

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Re: The bifilar pancake coil at its resonant frequency
« Reply #69 on: March 25, 2017, 05:42:21 PM »
Nice experiment, and a nice stack of pancake coils!

I've been wondering about charging a battery with the dielectric resonant voltage. Thanks for showing that it works.

Have you noticed a difference, in how the coil is connected? I noticed, north is stronger. Why do you not use 2 diodes, to create a plus and minus from the resonant sine wave?

really cool to hear it buzzing with the magnet on top. I hear my coils buzzing sometimes, when I load them unbalanced.

Quote from Miles High:

"The central issue is what is the reason for taking a bifilar pancake coil and exciting it at its self-resonant frequency?  Why do this?  What are you trying to accomplish? What practical applications are there for this"?

Skycollection is sending power with a longitudinal magnet wave wirelessly between his bifilar pancake coils at self resonating frequency. This conduit for power acts like a super conductor.

MileHigh

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Re: The bifilar pancake coil at its resonant frequency
« Reply #70 on: March 25, 2017, 06:15:34 PM »
What if I'm not at all interested in power transfer?  What if I'm after something completely different?

Can you answer me what it is I could possibly be looking for?

If you have no clue, maybe it's time to cease and desist.

I'm quite certain Nelson knows what I'm referring to.   ;)

I can't read your mind, period.  Power transfer was an example of a practical application for a coil.  So you tell me what you are looking for.  I would really like to know what you are referring to.

synchro1

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Re: The bifilar pancake coil at its resonant frequency
« Reply #71 on: March 25, 2017, 06:56:38 PM »
Tesla tried to sell his Wardenclyffe wireless power system with the advantage of instantly tailoring output to match the load. Currently, power companies pump water up hill at low usage times and release it through hydroelectric generators at peak demand hours.

Skycollection's wireless conduit works the same way as Tesla's system; Tesla could increase power with a transformer rheostat on demand. There is no current consumption. The voltage at the outlet is unchanged. When demand increases, higher voltage is sent instantly through the longitudinal magnet wave conduit, and spread evenly throughout the grid.

The advantage Skycollection's magnet wave conduit has over Tesla's original system, is that no one can steal the power like they may have from Tesla's World Wide Power broadcast system. Everyone's heard how J.P. Morgan had the Wardenclyffe tower dynamited when he realized there was no way to meter the usage. 
« Last Edit: March 25, 2017, 10:50:39 PM by synchro1 »

evostars

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Re: The bifilar pancake coil at its resonant frequency
« Reply #72 on: March 25, 2017, 07:16:24 PM »
Hi Nelson well it looks like we are on a learning curve here for through's [true?] coil winders who didn't know and the mothers who didn't teach manners and respect off other inner souls into there kids.
+1

opening our minds, requires opening our hearts

gyulasun

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Re: The bifilar pancake coil at its resonant frequency
« Reply #73 on: March 25, 2017, 07:27:52 PM »
How would you explain the doubling of magnetic strength in my "Tesla Coil Builder" bifilar vs. single wire electro-magnet test with the trombone paper clips?

Synchro1,

I am not qualified to explain your unique way of making electromagnets, magnetizing first the core that you intend to use in an electromagnet by blasting huge current via the nails etc etc.   I refer to your Reply #59 and #66 too.

All I can say is good luck to you.

Gyula

nelsonrochaa

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Re: The bifilar pancake coil at its resonant frequency
« Reply #74 on: March 25, 2017, 08:16:08 PM »
+1

opening our minds, requires opening our hearts

wise words! ;)