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Author Topic: The bifilar pancake coil at its resonant frequency  (Read 246799 times)

Offline tinman

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Re: The bifilar pancake coil at its resonant frequency
« Reply #825 on: April 15, 2017, 05:42:09 PM »
Brad: Your wirewound cement resistor probably has significant inductance too!

Ah yes
Will replace that with a carbon one tomorrow,and retry.


Brad

Free Energy | searching for free energy and discussing free energy


Offline MileHigh

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Re: The bifilar pancake coil at its resonant frequency
« Reply #826 on: April 15, 2017, 05:45:26 PM »
But you "made" it look way way worse than the actual outcome. Way worse. If you made that mistake working at a law firm you would be fired. By making it look that bad why would anyone in their right mind even try for themselves once they innocently take in your concocted results as 'fact', that are sooo far of it isnt even funny anymore.

I am not the bogeyman so stop the demonizing right now.  I gave you my explanation and you are not going to ignore it.  I did not "concoct" anything, period.

Here is your takeaway:  It looks like with any bifilar coil that you work with on your bench, to sustain a very small amount of energy in the resonant cavity, you have to continuously burn off a very large amount of power in the wire resistance relative to the resonant cavity energy.

Now, that is likely to be true for anybody's bifilar coil, period.

Offline gyulasun

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Re: The bifilar pancake coil at its resonant frequency
« Reply #827 on: April 15, 2017, 05:55:30 PM »


Also let's use Conrad's numbers again to look at the series bifilar coil a different way:

34 microhenries, 49 picofarads of self-capacitance

Let's just say that a reasonable peak-to-peak voltage for the self-resonating coil is 400 volts.

So the capacitive energy is 0.98 microjoules.
 

You calculated 0.98 uJ (microjoule) capacitive energy in a 49 pF capacitor when this cap has 400 V across it
as you defined in your example.

My calculation gives 3.92 uJ (microjoule). 

Quote
  Now, I am going to make an apples and oranges comparison here.  Let's assume the inductor
is pulsed at a low duty cycle in some kind of pulse circuit such that the average power dissipation from
the 10-ohm coil is low and not an issue, and the peak current through the coil is 400 milliamperes.

So the inductive energy is 2.72 mircojoules.

Well, in this apples and oranges comparison, the two energy levels are pretty comparable and it certainly
doesn't look like a gnat sitting on the back of an elephant.  However, there is one caveat. 
If the coil is functioning in some kind of pulse circuit the self-capacitance is not really there, there is
no real self-resonance taking place. 

I think you mean pulsing a bifilar coil at a low enough frequency well away from its self-resonant
frequency, right? If yes, then this mode of operation is not comparable to the circumstances
defined in Tesla's patent.   

And there is no sense to compare 2.72 uJ energy in the coil to 0.98 uJ energy in the capacitor (this latter
energy is 3.92 uJ by my calculation), albeit this certainly fits to your apples to oranges comparison.

By the way, is there any sense for making such apple-orange comparisons?

This question arises because in your next text you introduce another example where the self-resonance
voltage across a coil is 40 Vpp and then you compare this 0.0098 uJ energy to another coil pulsed with
a low duty cycle 400 mA peak current that creates 2.72 uJ energy... 

Quote
Finally, one last kick at the napkin.
If the self-resonance is say 40 volts peak-to-peak, then the energy stored in the self-capacitance
is 0.0098 microjoules.  And the energy in the coll at 400 milliamperes is 2.72 microjoules.
In this apples and oranges comparison the inductive energy is 277 times the capacitive energy. 

It is okay that you can compare apples to oranges as you wish but such comparisons are good fun
for some people but surely not scientific at all.

I am not nit-picking with you, no offense intended at all, simply trying to find sense in some of your posts
and / or trying to correct mistakes other readers here may not recognise and from your posts they may remain
with the bad impression: a bifilar coil as per the Tesla patent is good for nothing.
And no, I will not answer your would-be next question: what is the advantage of using a bifilar coil...  lol

Gyula

Free Energy | searching for free energy and discussing free energy

Re: The bifilar pancake coil at its resonant frequency
« Reply #827 on: April 15, 2017, 05:55:30 PM »
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Offline Grumage

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Re: The bifilar pancake coil at its resonant frequency
« Reply #828 on: April 15, 2017, 06:04:57 PM »
 ;)

Offline Magluvin

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Re: The bifilar pancake coil at its resonant frequency
« Reply #829 on: April 15, 2017, 06:10:57 PM »
You are missing the key point here.  Tesla states in the patent that at the right AC excitation frequency the bifilar coil (or any coil) will appear as a pure resistance.  This is where the coil is modeled as a series LC circuit.  And we know that when you excite a series LC circuit with a pure sine wave that the series LC circuit looks like the wire resistance only because at the right AC excitation frequency the reactance of the inductance and the capacitance cancel each other out.

So if you pulse a bifilar coil, this is not the same as pure sine wave excitation at the resonant frequency, and the "wire resistance only" statement does not apply.

He doesnt 'state' exactly what you quote in bold.  anyway....

Ok, so if it has to be the right freq, then what happens when we apply a dc input, pulse long, short, indefinitely on, what will happen when the current is applied? Is the coil not going to take the easy way upward in current at its resonant freq?  If the pulse were very short, AND he claims that the inductance is "neutralized" due to the capacitance mod, Why would the inductance at resonance be neutralized, but a pulse of dc cause the coil not to follow the upward 1/4 cycle of its resonant freq?

He does state that the the coil secures a capacity sufficient enough to neutralize the self induction. So it sounds to me like the capacity is sufficient enough to ignore the inductance with a pulse.

Its like this... If his claim is that the capacitance change, due to only the differential voltage difference in adjacent turns vs a normal winding, neutralizes the inductance, why would we be concerned that the inductance is neutralized only if it were driven by a particular freq? Like I get what you are saying, but what is the point of bringing up the neutralization due to the capacitance mod of a series bifi if it didnt mean anything and really doesnt need to be said? Resonance wasnt a new idea and was well known how to achieve it. He isnt making the claim on a resonance basis that had been understood for some time, as if it were new and he is describing the process of what happens to the inductance at only a particular freq. The claim is that the change in capacitance differential voltage due to the bifi winding vs normal causes the inductance to be neutralized. That is the claim. His 'claims are always at the bottom of the descriptions. 

We cannot compare this to a coil in parallel to an outside capacitance. Adding a capacitor as in a typical lc, a pulsed input would be mostly ignored by the coil and the cap would take on the pulse. And how fast does that cap take that pulse? Pretty darn fast. But that does nothing for the coil when considering we are looking for the possibility of a current 'through the coil' when the pulse is applied, not to just initially to an added cap of an LC.  And Im thinking he is saying what I have been explaining here. will see.

Mags



This is the claim of which is usually put after the description, and in a few different ways of saying it to cover his ass.. That is the claim Im referring to.



" A coil for electric apparatus the adjacent convolutions of which form parts of the circuit between which there exists a potential difference sufficient to secure in the coil a capacity capable of neutralizing its self-induction, as hereinbefore described."

Free Energy | searching for free energy and discussing free energy

Re: The bifilar pancake coil at its resonant frequency
« Reply #829 on: April 15, 2017, 06:10:57 PM »
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Offline MileHigh

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Re: The bifilar pancake coil at its resonant frequency
« Reply #830 on: April 15, 2017, 06:15:29 PM »
You calculated 0.98 uJ (microjoule) capacitive energy in a 49 pF capacitor when this cap has 400 V across it
as you defined in your example.

My calculation gives 3.92 uJ (microjoule). 

I think you mean pulsing a bifilar coil at a low enough frequency well away from its self-resonant
frequency, right? If yes, then this mode of operation is not comparable to the circumstances
defined in Tesla's patent.   

And there is no sense to compare 2.72 uJ energy in the coil to 0.98 uJ energy in the capacitor (this latter
energy is 3.92 uJ by my calculation), albeit this certainly fits to your apples to oranges comparison.

By the way, is there any sense for making such apple-orange comparisons?

This question arises because in your next text you introduce another example where the self-resonance
voltage across a coil is 40 Vpp and then you compare this 0.0098 uJ energy to another coil pulsed with
a low duty cycle 400 mA peak current that creates 2.72 uJ energy... 

It is okay that you can compare apples to oranges as you wish but such comparisons are good fun
for some people but surely not scientific at all.

I am not nit-picking with you, no offense intended at all, simply trying to find sense in some of your posts
and / or trying to correct mistakes other readers here may not recognise and from your posts they may remain
with the bad impression: a bifilar coil as per the Tesla patent is good for nothing.
And no, I will not answer your would-be next question: what is the advantage of using a bifilar coil...  lol

Gyula

Note that I said 400 volts peak-to-peak so I get the 0.98 microjoules from 200 volts.

The point of the exercise was just to try and get some kind of intrinsic feeling for what the bifilar coil's numbers and behaviour would be like in the real world.  Sure, I even stretched it to the point of breaking away from the Tesla patent and talked about pulsing the coil.  People are nearly obsessed with pulsing coils around here!  Like something like if you pulse the coil for say 50 milliseconds and you play with the timebase and gain and offset of your scope display you might see tiny bits of resonant ringing at the start and end of the pulse that you can trace back to the self-resonance of the coil.

Quote
And no, I will not answer your would-be next question: what is the advantage of using a bifilar coil...  lol

Sort of reminds me of this:   :)

http://www.reuters.com/article/us-alaska-bridge-idUSKCN0SI00120151024

Offline Magluvin

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Re: The bifilar pancake coil at its resonant frequency
« Reply #831 on: April 15, 2017, 06:33:32 PM »
ok,below is my bifilar coil.
It is made from heavy gauge rectangular ali enameled wire-so the winds sit nice and neat together.

I am just running an AC current through it,via my SG-so very low powered.

But here is the kicker,after a quick 10 minutes of testing.

The voltage generated across the sniffer coil,is in phase with the voltage across the bifilar coil,and not in phase with the current through the bifilar coil. The current through the bifilar coil is 90* out of phase with both the voltage across the bifilar and sniffer coils  :o

Tomorrow i will wind a single layer coil of the same amount of turns,and see if it is the same.


Brad

Nice. Can you show a closeup of the wire? I was just talking about square wire. Also could you measure the capacitance between the windings? Separated of course not in series connection. Just interested to see what you get.with that wire with more close proximity surface area.  Its gota be more than conrad had with the insulation and round wire. Not putting his effort down, just to see if you get better capacitance with what you got.

Mags

Free Energy | searching for free energy and discussing free energy

Re: The bifilar pancake coil at its resonant frequency
« Reply #831 on: April 15, 2017, 06:33:32 PM »
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Offline Magluvin

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Re: The bifilar pancake coil at its resonant frequency
« Reply #832 on: April 15, 2017, 06:52:29 PM »
Silly question time.

Does the C need to be "pre charged" for it to cancel the L?

Does the applied voltage to the bifi pre charge the C before current flow?

This is what I was trying to explain in my understanding of the difference between a typical LC and a series bifi....

Like if we have a cap and coil in parallel and apply an ac input of the proper freq to ring, the induction is not ignored or even neutralized as tesla claims of the series bifi. The induction is there and functioning just as it should. If a pulse input is applied to the LC, the cap will charge fast and the inductor will impede the pulse. Then the cap will discharge into the inductor and ring till dead or till the next pulse. This is where Teslas claim is different. He is basically saying the capacitance 'in' the series bifi will take on charge ignoring the inductance, or as he says it is neutralized. So what does that mean for current entering the coil from the initial application of input???  ;) Im thinking it means the coil will build a field either instantly or even much faster than a normal inductor of the same wire and size. Normally we are restricted to particular upper freq limits of inductors as they are low pass filters. But what if that same inductor were able to reach max current much faster or even instantly if the inductance is ignored or neutralized?? What affect would that have on a secondary vs a slow climb with an inductance that only lets the current rise in the pri over time?

So the 2 are not the same. The LC cap and separate coil are one thing and the bifi is another. The bifi coil takes on current, through the windings to charge the capacitance. And if the inductance is neutralized due to the coils structure capacitance change, then that capacitance should charge as fast as a cap, AND produce a mag field that builds as fast as the bifi cap will take the current from the input. So IM thinking the 2 are different and we will have to see.

Mags

Offline Magluvin

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Re: The bifilar pancake coil at its resonant frequency
« Reply #833 on: April 15, 2017, 06:53:34 PM »
Mags:
(no bitch)

BITCH !!

Yes. Tedious. And nice.  ;D

Mags

Free Energy | searching for free energy and discussing free energy

Re: The bifilar pancake coil at its resonant frequency
« Reply #833 on: April 15, 2017, 06:53:34 PM »
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Offline Magluvin

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Re: The bifilar pancake coil at its resonant frequency
« Reply #834 on: April 15, 2017, 06:54:54 PM »
;)

Dang, lets all just get together and have a bifi coil show!   ;D Nice


Mags

Offline gyulasun

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Re: The bifilar pancake coil at its resonant frequency
« Reply #835 on: April 15, 2017, 07:00:44 PM »

Note that I said 400 volts peak-to-peak so I get the 0.98 microjoules from 200 volts.


I am surprised by your answer.   Please explain what conversion did you make to get 200 V from 400 V?
I knew you must have entered 200 V into the formula to get 0.98 microjoule
energy in a 49 pF capacitor but now there is another problem...

The moment the voltage level is just say 400 V across a capacitor (i.e. you can measure it in that moment),
then you have to use 400 V in the formula to get the stored energy in that moment.
Such moments always occur in resonant LC circuits whenever all the coil energy has just 'gone' into the
capacitor and the coil has no any magnetic energy left in it.  And the received energy in the capacitor manifests
as a peak to peak voltage across it but you need not convert this to any other voltage value at all, okay?

Gyula

Free Energy | searching for free energy and discussing free energy

Re: The bifilar pancake coil at its resonant frequency
« Reply #835 on: April 15, 2017, 07:00:44 PM »
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Offline Grumage

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Re: The bifilar pancake coil at its resonant frequency
« Reply #836 on: April 15, 2017, 07:06:08 PM »
Dang, lets all just get together and have a bifi coil show!   ;D Nice


Mags

Thanks Mags.

That BiFi coil is damaged, overstressed, broke the insulation down.

I would suggest a good coat of Shellac be applied if you're going to use one on an Induction hob....  ;)

Cheers Graham.

Offline MileHigh

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Re: The bifilar pancake coil at its resonant frequency
« Reply #837 on: April 15, 2017, 07:10:08 PM »

My point is unlike you, I have a solution.....smartass...

I have a solution.

So what's your solution?  If you refuse to answer, then what's the point?

Offline MileHigh

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Re: The bifilar pancake coil at its resonant frequency
« Reply #838 on: April 15, 2017, 07:13:18 PM »
I am surprised by your answer.   Please explain what conversion did you make to get 200 V from 400 V?
I knew you must have entered 200 V into the formula to get 0.98 microjoule
energy in a 49 pF capacitor but now there is another problem...

The moment the voltage level is just say 400 V across a capacitor (i.e. you can measure it in that moment),
then you have to use 400 V in the formula to get the stored energy in that moment.
Such moments always occur in resonant LC circuits whenever all the coil energy has just 'gone' into the
capacitor and the coil has no any magnetic energy left in it.  And the received energy in the capacitor manifests
as a peak to peak voltage across it but you need not convert this to any other voltage value at all, okay?

Gyula

The model is a self-resonating bifilar coil with a ground reference on one terminal and the other terminal swinging back and forth between +200 and -200 volts.

Offline MileHigh

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Re: The bifilar pancake coil at its resonant frequency
« Reply #839 on: April 15, 2017, 07:18:36 PM »
Also could you measure the capacitance between the windings? Separated of course not in series connection. Just interested to see what you get.with that wire with more close proximity surface area.  Its gota be more than conrad had with the insulation and round wire. Not putting his effort down, just to see if you get better capacitance with what you got.

Note that Conrad calculated the capacitance based on the self-resonant frequency and I don't think he made a measurement with the separated windings.  My gut feeling is that the capacitance measured between the separated windings will be in the same ballpark as the calculated capacitance from the self-resonant frequency but I am really not sure.

 

OneLink