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Author Topic: Bifilar pancake coil overunity experiment  (Read 93477 times)

F6FLT

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Re: Bifilar pancake coil overunity experiment
« Reply #135 on: October 14, 2018, 03:31:43 PM »
I'm sorry, reading things here, get some new ideas. Or just to explain. TinselKoala thought that a coil, and a capacitor in parallel with it or something, is an equivalent of a bifilar coil that has capacitance. This is certainly not the equivalent, one thing it has not twice the inductance of the ordinary coil, as a bifilar coil has.
...

I think this TinselKoala's view of the bifilar coil is right in the quasi-stationary states approximation. We only have a resonant classical LC circuit.
But when the length of the coil if of the same order as the wavelength of the signal frequencies, stranger things begin to appear.
It doesn't matter the coil is monofilar or bifilar, only wire length and capacity matters: the coil becomes a transmission line BUT a signal can pass through the coil diametrically, through the inter-turn capacity, and we have a possible overlap of the two phenomena.

The coil in the photo is monofilar, it is connected to nothing but weakly coupled by induction to two turns of the red wire that can be seen, which is connected to a signal generator. Its resonance frequency is about 1.5 MHz and rather sharp.
By injecting the signal directly into the external end of the coil, not by induction, the resonance is at approximately the same frequency.

According to a measurement of a second coil of 55nF, bifilar this one, with copper strips 5 mm width, I estimate the capacitance of the first one in the photo, 1.5 cm width and tighter turns, to be more than 200nF.
With such a capacity associated with such an inductance, it is impossible to get a resonance at 1.5 MHz but only at a few KHz or tens of KHz. The resonance is therefore not related to the LCω² product.

To set things straight, I wanted to measure the transmission time. I injected a 16 ns pulse into the outer end of the coil (not in the photo). I connected the inner end to the ground with a 47 ohm resistor at the terminals of which I observed the output signal. The pulse repetition frequency was only 1 KHz so that possible echoes from one pulse do not interfere with the next.
To my great surprise, I didn't notice any delay! On the scope screenshot (20 ns/div), you can see that the pulse passes directly through the coil: the output is activated almost simultaneously with the input, and we see that the effect is capacitive thanks to the negative value of the output during the falling edge of the pulse. More surprisingly we don't see any other signals, no delayed pulses.

The coil length is 30 m. The quarter wavelength at 1.5 MHz is 50m. With a coefficient of velocity of 0.6, the coil length fits a quarter length resonance. It remains a pure speculation because the coefficient of velocity is strangely low and also because I don't observe echoes when I use pulses!

I think we need to clarify these elementary effects of a capacitive coil before we go further. For me it's really unclear, and yet I'm familiar with RF devices.


ayeaye

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Re: Bifilar pancake coil overunity experiment
« Reply #136 on: October 14, 2018, 05:25:14 PM »
So it acts as a capacitor? But the oscillation in the end is because of coil?


F6FLT

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Re: Bifilar pancake coil overunity experiment
« Reply #137 on: October 14, 2018, 10:05:45 PM »
My interpretation: it's like a RC circuit, C being the capacity of the coil and R the terminal load where we take the output signal. There is a slight delay due to the circuit time constant t=RC.

Since the capacitor is in parallel with the coil, the resistance of the coil discharges the capacitor.
As a first result, the falling edge of the input pulse causes the output pulse to drop below zero because at the time of the drop, the capacitor was already no longer charged to the maximum value required by the upper level of the input pulse.
As a second result, after the lowest point, which is a negative potential while the input pulse is always positive,  the discharge of the capacitor causes the signal to return to zero after the end of the input pulse, and I suppose that it is the part of the signal that you see as an "oscillation".

I think that the weirdness come from the fact that we have a special transmission line: like a transmission line it has a distributed inductance and capacitance, but unlike a real transmission line, the capacitance is instantly linking all "section" of the line together.

I'm not sure at all of what I said. May be I'm wrong. Other interpretations are welcome.
The fact that I don't see a pulse delayed by the time needed to move along the line and yet by using a sinusoidal signal, I get a resonance at a frequency without any relation to the LC time constant is very annoying!

gyulasun

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Re: Bifilar pancake coil overunity experiment
« Reply #138 on: October 14, 2018, 10:43:57 PM »
Hi F6FLT,

Would you clarify little more precisely how you connected the bifilar (copper strip) coil? Are the other two ends
of the coil left floating independently or they are connected together and left floating?
From your measurements, if I understood it correctly, could it be deduced that your bifilar coil as you connected it
behaves like a series LC circuit (at 1.5 MHz) resonance?
I mean as if a series (lumped) LC is driven at one end from the "hot" output of a generator and its other end is
connected to a 47 Ohm resistor across which your scope probe is connected and the ground of the generator is
connected to the cold end of the 47 Ohm (and to the ground of the scope of course).

Thanks,
Gyula

ayeaye

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Re: Bifilar pancake coil overunity experiment
« Reply #139 on: October 14, 2018, 11:53:33 PM »
Gyulasun, as much as i understand, this was, a pulse from the signal generator, through the coil, there was a resistor in series with the coil, and the voltage was measured on that resistor. Like on the figure below i guess. So it seems to be, like resistance was charged, then when the pulse ended, it discharged. But i'm not sure whether i understood rightly. What i asked was, in the end of the negative part of the signal, there is some ringing, waving or such, i ask whether this was caused by the coil.

Traces of the F6FLT experiment drawn with Inkscape, and converted to samples. 50 units per square (scale), the drawing precision is great enough.

ch 1

https://trinket.io/python/69a421854d

ch 2

https://trinket.io/python/61f11be8fe

On the next figures are the gnuplot plots of ch1, input part and output part.

F6FLT, what were the scales of ch 1 and ch 2 on your traces? I assumed 5 V and 0.2 V but i couldn't really read it from your screen image.

With that not right the calculations below are not correct at all. So below are the obviously absurd results with the assumed scale values.

Calculation of the input part and its output.

https://trinket.io/python/4d26084a5b

Quote
Input power was 21.5164 uW

Calculation of the output part and its output.

https://trinket.io/python/ea65242ecf

Quote
Output power was 0.0097 uW

It may be simpler to do it in that way in some respect, but only the signal generator output can take it, a ttl output cannot take it, thus the need for transistor. If one has no signal generator. But calculations are more complicated, and there is a need to measure two channels, which greatly increases the error, so doing it with transistor is clearly better.

Make the resistor much greater maybe, perhaps you waste so much power.

Please if you want to change the Trinket Python scripts above, make first your own fork, that is, get a different link, go there, and then change it there, but make sure that the link is different, don't change the script at the original link please.

Just in case i just write here the actual calculation parts when using the circuit below. For calculating input, two input files were used, for ch 1 and ch 2 lists. Assume that v is the voltage on the output of the signal generator, vl is the voltage on the coil, vr voltage on the resistor, pl power in the coil, and pr power in the resistor, R is the resistance of the resistor (in ohms), and e is the sum of powers at the instants of time. Voltages are in mV, thus dividing by 1000 when calculating power, to get mW.

Input power calculation.

Quote
vl = v - vr
il = vl / R
pl = vl * il / 1000
e += pl

Output power calculation.

Quote
pr = vr * vr / R / 1000
e += pr

« Last Edit: October 15, 2018, 11:45:00 AM by ayeaye »

F6FLT

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Re: Bifilar pancake coil overunity experiment
« Reply #140 on: October 15, 2018, 10:06:37 AM »
...
Would you clarify little more precisely how you connected the bifilar (copper strip) coil? Are the other two ends
of the coil left floating independently or they are connected together and left floating?
From your measurements, if I understood it correctly, could it be deduced that your bifilar coil as you connected it
behaves like a series LC circuit (at 1.5 MHz) resonance?
I mean as if a series (lumped) LC is driven at one end from the "hot" output of a generator and its other end is
connected to a 47 Ohm resistor across which your scope probe is connected and the ground of the generator is
connected to the cold end of the 47 Ohm (and to the ground of the scope of course).
...

Hi Gyula,

It's not a bifilar coil but monofilar. My first tests were made with a bifilar coil that gave bizarre results, so I simplified for a monofilar coil (that gives the same bizarre results).
My method is to go towards the most elementary phenomena with the simplest possible configuration. Now I just want to qualify the properties of a coil having a very high distributed capacity (> 200 nF for mine, like this one but wider : https://www.amazon.co.uk/6mmx30-Copper-Horse-Irmband-Adhesive/dp/B016Y58PPG/ref=sr_1_5 ).

All your other considerations are perfectly correct. I use the schema given above by ayeaye.

My main question is: why is there a resonance at 1.5 MHz while L and C are obviously too big values to reach this frequency?

(It's may be interesting to know that with my bifilar coil of same length, which was 0.6 cm wide instead of 1.5 cm for the monofilar and not so tight turns, the resonance frequency was 2.3 MHz when both wires are not connected together and no resonance when in series).


itsu

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Re: Bifilar pancake coil overunity experiment
« Reply #141 on: October 15, 2018, 11:50:58 AM »

Hi F6FLT,


Quote
My main question is: why is there a resonance at 1.5 MHz while L and C are obviously too big values to reach this frequency?

Why do you think L is to big here?  Did you measure it?  What was the value?

According to http://www.1728.org/resfreq.htm , the inductance at 1.5Mhz with 200nF is 0.056uH (56nH).

According to https://www.emisoftware.com/calculator/stripline/ , the biplanar inductance of a stripline
with Width=15mm, seperation=1mil and length=30m is 6.384e-8H = 0.06348uH = 63.48nH

I know that the biplanar configuration is not like your coiled up strip, but it confirms that striplines are
known for their low inductance as you will know.

Itsu


ayeaye

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Re: Bifilar pancake coil overunity experiment
« Reply #142 on: October 15, 2018, 12:33:48 PM »
Channel 1 measures vs, and channel 2 measures vr. Typical calculation of power from voltage, nothing complicated. Divide by 1000 as voltages are in mV, to get mW.

p = v * v / R

The input part.

Quote
vl = vs - vr
pl = vl * vl / R / 1000
e += pl

And the output part.

Quote
pr = vr * vr / R / 1000
e += pr

The following things are important to consider.

* We calculate input and output power only for the coil.

* We calculate instantaneous power for the input part, as the power consumed by the coil.

* We calculate instantaneous power for the output part, as the power generated by the coil, that was consumed by the load resistor.

Because the voltage on the coil has to be calculated from the voltage on the signal generator and the voltage on the resistor, both the voltage on the resistor and the signal generator voltage, have to be measured.

Unless it is known that during all the input part the signal generator voltage didn't change, and this voltage is known. Then only one channel, the voltage on the resistor, has to be measured.

In the case above, the signal generator voltage did change, thus two channels had to be measured, and included in the calculations.

To fork Trinket Python code make a small unimportant change, like add a space to the beginning of a comment, which after making a fork can be changed back. When making a fork after that, the link provided will be different from the page where the original code is. This is inconvenient, with otherwise so nice tool.

« Last Edit: October 15, 2018, 05:02:25 PM by ayeaye »

F6FLT

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Re: Bifilar pancake coil overunity experiment
« Reply #143 on: October 15, 2018, 02:03:29 PM »
Hi F6FLT,


Why do you think L is to big here?  Did you measure it?  What was the value?

According to http://www.1728.org/resfreq.htm , the inductance at 1.5Mhz with 200nF is 0.056uH (56nH).

According to https://www.emisoftware.com/calculator/stripline/ , the biplanar inductance of a stripline
with Width=15mm, seperation=1mil and length=30m is 6.384e-8H = 0.06348uH = 63.48nH

I know that the biplanar configuration is not like your coiled up strip, but it confirms that striplines are
known for their low inductance as you will know.

Itsu

Hi Itsu

The thickness of the winding is 20 mm and there are about 95 turns. We have 20/95=0.2mm for the thickness of the strip, including conductor + insulation. Reporting width=15mm, separation=0.2mm, length=30m in your site, we get an inductance of 125 nH.

This value being not so far from a resonance at 1.5 Mhz, I decided to calculate more precisely the capacity for which I had given the minimum value of 200nF.
I had measured 55 nF for the bifilar coil (tape width 6 mm, same length). So my monofilar coil  (width 15 mm) would have a capacity of 55*15/6 = 137 nF. But the monofilar coil has turns much more tight, the thickness of the winding is 2 cm while it is 5 cm for the bifilar coil. The capacity of a plate capacitor being insersly proportional to the thickness of the dielectric, this leads us to a capacity of 137*5/2=342 nF.

This give us a frequency of 770 KHz, about the half of what is observed. Nevertheless you are right. Taking into account the margins of uncertainty, we are in the correct order of magnitude, unlike what I thought. I must have been mistaken by my habit of using capacitors of only a few hundred pF to obtain resonances at about 1 MHz which is the AM MW radio band, and with much smaller coils (in volume) but probably not in value due to the ferrite core....  :-[

So there is no mystery here. This flat capacitive coil works strictly like a normal coil tuned with an external capacitor.
Probably we can explain the absence of propagation of a pulse in the line because we are really in the approximation of quasi-stationary states: the capacity concerns the whole winding as a block, and each coil turn shares the same magnetic field, so that at a given time, currents and voltages do not depend on the position that is measured in the circuit.

So now I have to go back to the bifilar coil.

Thanks


itsu

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Re: Bifilar pancake coil overunity experiment
« Reply #144 on: October 15, 2018, 04:35:29 PM »

F6FLT

concerning the pulse, i am not sure if one could use such a Time Domain Reflection setup:
https://en.wikipedia.org/wiki/Time-domain_reflectometer on a single wire.

Its used on transmission lines (coax etc.) which have 2 wires.
The reflected pulse, when shorted, comes back as a negative pulse and with an open at the end as a positive pulse
(hmmm, could that be considered as a single line?   I don't think so as we miss the distributed capacitance and
inductance between the 2 wires).

Itsu

gyulasun

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Re: Bifilar pancake coil overunity experiment
« Reply #145 on: October 16, 2018, 12:30:58 AM »
Hi F6FLT,

Okay on your monofilar coil and not a bifilar one.

The reason I believed you had referred to a bifilar coil was because you wrote this in your Reply 135:

...
According to a measurement of a second coil of 55nF, bifilar this one, with copper strips 5 mm width, I estimate the capacitance of the first one in the photo, 1.5 cm width and tighter turns, to be more than 200nF.
...
Anyway, no problem.

I would suggest two measurement methods to arrive at your coil's self capacitance value. One is described here in Answer 6, scroll down to about the middle: https://forum.allaboutcircuits.com/threads/measure-capacitance-in-a-coil-of-wire.8660/   
I think in that measurement method capacitor C2 should have a lower value than C1.  So you need say at least a C2=100 nF and say C1=220 nF good quality capacitor for such measurements. Of course, lower values at hand would also do.

The second method can be derived from this interesting current amplifying resonant circuit shown here:
https://www.accelinstruments.com/Applications/WaveformAmp/Magnetic-Field-Generator.html   (this paper was already mentioned in this forum and at other forum I think)
This paper can also be found here:
https://www.electronicdesign.com/analog/resonant-circuit-generates-high-frequency-magnetic-field

I mean that in the circuit shown in Figure 4, capacitor Cp would be the self capacitance of your monofilar (or bifilar) coil which gives the 1.5 MHz parallel resonance as you already measured.  And capacitor Cs should be chosen so that you get a series resonance with it when the generator is set to 0.707 x 1.5 MHZ = 1.06 MHz frequency.  And the value of the Cs capacitor when it series resonates your coil at 1.06 MHz will be equal to the self capacitance of the coil.
Maybe this method is harder to use because one would need a capacitor box adjustable in the some 10 nF values in some nF steps.

Gyula

gyulasun

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Re: Bifilar pancake coil overunity experiment
« Reply #146 on: October 16, 2018, 12:41:20 AM »
Gyulasun, as much as i understand, this was, a pulse from the signal generator, through the coil, there was a resistor in series with the coil, and the voltage was measured on that resistor. Like on the figure below i guess. So it seems to be, like resistance was charged, then when the pulse ended, it discharged. But i'm not sure whether i understood rightly. What i asked was, in the end of the negative part of the signal, there is some ringing, waving or such, i ask whether this was caused by the coil.

....
Hi ayeaye,
Thanks for making the schematic for the F6FLT coil setup, that is also how I imagined. 

Regarding your question on the negative part of the output waveform, it should come from the resonant LC circuit behaviour when the self capacitance part of the coil charges back current with an opposite polarity and the coil will have an opposite magnetic field like earlier, a normal LC resonant tank circuit behavior takes place: magnetic and electric energy changes back and forth.  No matter whether you have a distributed capacitance or inductance like in a transmission line or in such flat strip wound coils or you have a normal lumped element LC components.  And even if there is no direct resonance between the input pulse frequency and the LC circuit resonant frequency, the energy ping-pong is able to happen to a certain degree, hence a negative voltage can appear too.

Gyula

ayeaye

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Re: Bifilar pancake coil overunity experiment
« Reply #147 on: October 16, 2018, 07:19:26 AM »
This Trinket Python shell, it's a kind of weird, but it's a good thing. You make changes, run, even go back to that page later, and the changes are there. Yet after some time, the changes are gone, and it's back again as it previously were.

The only way to make the changes permanent, is to make changes, and then fork.

I saw no easy way to get an empty Python shell to play with, so the following is the one that i made. Fork it, then change it, then fork it again.

https://trinket.io/python/ab5dff2b29

There are two ways, a convenient way, and a way that always works. The following is how to go through two input files. You can likely figure out how to modify it, to go through whatever number of files. There is one more thing though. Like len(s1) < 2, if the length of the line that we just read from file, is less than 2, right? Trinket always has only one character, line feed, at the end of the line. Now if we don't want empty line, we end reading the file when the length < 2. But if we read like an svg file, it can have empty lines in it, and we should only end when the length is < 1. I hope this was not too difficult to understand, if anyone reads at all.

Quote
f1 = open("input1.txt")
f2 = open("input2.txt")
while (True):
    s1 = f1.readline()
    s2 = f2.readline()
    if (len(s1) < 2 or len(s2) < 2): break
    #Your code goes here
f1.close()
f2.close()

The following are the scripts how they should be, i didn't make the changes in the previous ones permanent i think, though they too work.

Input part calculation.

https://trinket.io/python/93b0840917

Output part calculation.

https://trinket.io/python/7b498b9a8c


ayeaye

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Re: Bifilar pancake coil overunity experiment
« Reply #148 on: October 16, 2018, 08:31:53 AM »
a normal LC resonant tank circuit behavior takes place

Yes that was all that i said. As in the F6FLT's last test, the negative part of the waveform was due to the capacitance, the capacitance discharging when the signal generator output went to zero. But i said that we see some waving in the negative part, and this i think was due to this equivalent LC circuit oscillating. Which was maybe the only way how the coil's inductance revealed itself in that waveform.

How the capacitive coil is different from an ordinary LC circuit, is that current doesn't have to go through all the coil for induction to start in some part of the coil. But it may also mean that the current doesn't have to go all the way through the coil to charge the capacitance by induction, and the less current through the coil, the less lenz effect there may be.

There is always input and output part. And it is determined by whether there is any external supply of power or not. Like in the circuit that F6FLT used, when the output of the signal generator is greater than zero, a power is supplied to the coil and its capacitance, and this is the input part. But when the signal generator pulse ends, the signal generator becomes like connected to the circuit ground, and all the power in that circuit then comes only from the coil and its capacitance. Thus this is the output part. There is overunity when more energy is generated during the output part by the coil and its capacitance, than consumed by the coil during the input part.

F6FLT, please increase the resistor a lot, you waste terribly lot of energy, by the calculations i made that's insane. I guess the resistor should also be such that it fills the coil's capacitance in any observable time, otherwise there is too much input energy, and it kind of floods it. Oh wait, the time constant to charge the capacitance 63%, is RC, which in your case is 47 * 200 = 9400 nanoseconds, that is 9.4 us, which is a lot greater than your 16 ns pulse, it should not charge all the coil without any delay. Now i don't know. Because of the time constant, it has time to charge the capacitance only a tiny amount during the 16 ns pulse. Which may happen instantly, i don't know. But the calculations also show that the output power in your case must be very small.

« Last Edit: October 16, 2018, 10:52:35 AM by ayeaye »

ayeaye

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Re: Bifilar pancake coil overunity experiment
« Reply #149 on: October 17, 2018, 07:11:29 AM »
What am i doing? The only thing i provide is a method of doing experiment. No new circuits or anything.

But what was i thinking. The following is the right calculation for the input part.

Quote
vl = vs - vr
pl = vl * vr / R / 1000
e += pl

Notice there, it's vl * vr / R, not vl * vl / R as i wrote before, never do that mistake. There, vr / R is really current going through the coil.

Calculation for the output part is still the same.

Quote
pr = vr * vr / R / 1000
e += pr

The following are the correct Python scripts in Trinket, use only these, not the previous ones.

Calculation of the input part and its output.

https://trinket.io/python/8b7ea90215

Quote
Input power was 0.7622 uW

Calculation of the output part and its output.

https://trinket.io/python/e181754f5f

Quote
Output power was 0.0111 uW

As you can see, the input power is almost a hundred times more than the output power. And this is likely because the pulse length is hundreds of times less than the time constant, and during that time only a tiny amount of the coil's capacitance can be charged.

Empty Trinket script, to play with. There int(s) would be a number in the input, when there is an integer on the line, or it's float(s). Output first number of the two number csv  print(int(s[: s.find(",")]))  and the second number  print(int(s[s.find(",") + 1 : ])).

https://trinket.io/python/ab5dff2b29

The Trinket online Python can also do some plotting, with matplotlib.pyplot, but only a part of it is available. The input has to be stored in a list for that. Yes sure one can plot the lists, but the image would be rather small, and the only way to save it, seems to be screenshot. I prefer to use gnuplot for plotting, but the figure below was plotted with Trinket and Python, using the following script.

https://trinket.io/python/1c378d0174

« Last Edit: October 17, 2018, 12:55:44 PM by ayeaye »