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Author Topic: AC voltage from single magnetic pole  (Read 39114 times)

nix85

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Re: AC voltage from single magnetic pole
« Reply #75 on: October 09, 2020, 06:41:46 PM »
You mixed the turns, voltage coil should have little turns, not vice versa.

Also you moved magnet by hand altho inductive reactance is undetectable at such low frequency.

It's funny how you try to prove he's right with resistive coils while doing the test wrongly forgetting he is making a claim for PURELY INDUCTIVE COIL.


ramset

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Re: AC voltage from single magnetic pole
« Reply #76 on: October 09, 2020, 06:47:06 PM »
NX85
Your use of word “Friends “
Is silly
Implying nonsense


Better to stick to Brutal honesty


There are no “Friends “ when it comes
To truth


Just prove the point on your bench
Or accept a bench you will aprove for test !


And set criteria


You are fortunate to be amongst brutal honesty
Not “friends “
Regardless the outcome


The truth matters
And will rule the day !!




nix85

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Re: AC voltage from single magnetic pole
« Reply #77 on: October 09, 2020, 07:06:46 PM »
NX85
Your use of word “Friends “
Is silly
Implying nonsense


Better to stick to Brutal honesty


There are no “Friends “ when it comes
To truth


Just prove the point on your bench
Or accept a bench you will except for test


And set criteria


You are fortunate to be amongst brutal honesty
Not “friends “
Regardless the outcome


The truth matters
And will rule the day !!

It's not silly, there is a clear desire here to prove him right, call it friends or whatever.

Only truth matters, that i agree.

Just don't forget his claim is for pure inductive coil.

Here is one bench test showing clear 90° IV phase shift with aircores.

From description

"In this configuration the little flat coil with negligible inductance read only voltage and detect the position of magnets, the other coils are closed in loop and read the current across one shunt resistor of 10 Ohm. "

https://www.youtube.com/watch?v=m6AOTQlHhTU&

verpies

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Re: AC voltage from single magnetic pole
« Reply #78 on: October 09, 2020, 07:34:49 PM »
That is relative thing since all physical laws can be skewed or bypassed in certain ways but within certain limits they hold true, see below for an example.
I am all for designing a good experiment that will not skew or obscure the phenomenon being studied.

Your belief.
You are right to call it a belief or a hypothesis or a conjecture until I proove or disproove it according to the scientific method e.g. with falisifibility and replicatibility.

Ohm's law has it's exceptions, incandescent bulb totally ignores Ohm's law, as filament gets hotter it's resistance increases and Ohm's law is out of window,
Not really, it is just a badly designed experiment, namely two disparate measurements of the filament in two very different physical conditions.
If the resistance measurement of a hot filament is made then the Ohm's Law holds.

Show me a near purely inductive circuit in which current does not lag voltage as magnet passes across the coil and i'll be happy to admit this law is bypassed in such case.
OK, but as you have just illustrated, a badly designed experiment will yield bad results, so we will have to design a good experiment to which we both agree.

PS. since you will using resistive coil to prove something about ideal coils, use as thick wire as possible and at least 50 turns.
I could use a NbTi coil but the dewar will obscure its view and the LH is is expensive and will break the clamp-on current probe for oscilloscope.


To do it right you should use two coils, one for voltage and another for current, measure current with a clamp probe for oscilloscope.
That is doable with two identical low-resistance coils and two identical magnets, but the coil for measuring induced voltage should not be in close proximity to the shorted coil used for measuring current because the latter may distort the permanent magnet's flux which reaches inside the former coil.

IMO it is important, that the two coils and magnets are identical to prevent any differences in their behavior. This should be verifiable by swapping their roles at any time.
Also, I think that when both coils are opened and used for induced voltage measurement, then both voltage waveforms generated by them, should be identical and appear in-phase on the scope. Two out-of-phase induced voltage waveforms would indicate misalignment and would necessitate calibration of the apparatus.


Do you think that a result of such experiment would constitute an objective proof or disproof of the 1 BTC challange ?

ramset

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Re: AC voltage from single magnetic pole
« Reply #79 on: October 09, 2020, 07:38:26 PM »

NX85 (sorry I posted while Verpies was commenting)Well actually
I beg to differ


It seems your impression is not accurate


I have heard from both sides
And it seems a very good discussion to have


Please do not think any here would be disengenuos
Or dishonest to support an associate (we who hunt FE are all associates)


Science has no friends and should have no agenda other than the truth


Please move forward
Is the post #45 here the issue of contention?


Respectfully
Chet

nix85

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Re: AC voltage from single magnetic pole
« Reply #80 on: October 09, 2020, 07:45:56 PM »
Not really, it is just a badly designed experiment, namely two disparate measurements of the filament in two very different physical conditions.
If the resistance measurement of a hot filament is made then the Ohm's Law holds.

Wow, you must be a genius. Totally blew my mind. :)

It was just an example how law can be perceived as violated when it really was not.

As usual, you missed the point.

Quote
OK, but as you have just illustrated, a badly designed experiment will yield bad results, so we will have to design a good experiment to which we both agree.By turning on a very small (mW) heater, you can locally heat the superconducting loop so it becomes resistive. Now you can apply a voltage to the circuit - and it will preferentially send current around the superconducting part of the loop. The current will not be infinite though - for a given inductance L, the magnet will "ramp" as the current increases according to
V=−LdIdt

What i referred to was not an experiment.

Quote
I could use a NbTi coil but the dewar will obscure its view and the LH is is expensive and will break the clamp-on current probe for oscilloscope.

That is doable with two identical low-resistance coils and two identical magnets, but the coil for measuring induced voltage should not be in close proximity to the shorted coil used for measuring current because the latter may distort the permanent magnet's flux which reaches inside the former coil.

IMO it is important, that the two coils and magnets are identical to prevent any differences in their behavior. This should be verifiable by swapping their roles at any time.
Also, I think that when both coils are opened and used for induced voltage measurement, then both voltage waveforms generated by them, should be identical and appear in-phase on the scope. Two out-of-phase induced voltage waveforms would indicate misalignment and would necessitate calibration of the apparatus.

Do you think that a result of such experiment would constitute an objective proof or disproof of the 1 BTC challange ?

I just linked to a video of perfect 90° phase shift in closed aircore coil.

You claim coil without resistance would have 0 phase shift.

I leave it to you to prove your claim in objective, scientific manner.

This guy put it nicely...

"In a superconductor, the current can keep flowing "forever" since there is no resistance. But since conductors have inductance (in fact, superconductors are used most often to create magnets like for an MRI scanner), applying a voltage would not (immediately) cause an infinite current to flow.

By turning on a very small (mW) heater, you can locally heat the superconducting loop so it becomes resistive. Now you can apply a voltage to the circuit - and it will preferentially send current around the superconducting part of the loop. The current will not be infinite though - for a given inductance L, the magnet will "ramp" as the current increases according to V=−LdI/dt"

https://physics.stackexchange.com/questions/179374/is-current-in-superconductors-infinite-if-they-have-0-resistance-then-i-v-r-s

verpies

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Re: AC voltage from single magnetic pole
« Reply #81 on: October 09, 2020, 08:04:07 PM »
Video link:
https://vimeo.com/466592675
Thank you for doing that experiment, but I am afraid that it will not put this dispute to bed.


This is because this experiment was designed according to your ideas and not nix85's.  The rules of science say that both parties must agree to the experimental conditions.


1) We both don't like ferromagnetic cores in the coils, because ferromagnetism is a very complex secondary phenomenon and we are trying to avoid such confounding factors.


2) Nix85 wants to use 2 coils. One for measuring current and one for measuring voltage. While I don't think two coils are necessary to prove/disprove the issue at hand, I want to accommodate him ...and since two identical coils will not skew the experiment,  I agree to them.


3) I think the voltage signals form the two open coils should be identical and in-phase for the purpose of the calibration of the apparatus and the coils cannot be in close proximity ...and in your apparatus this means two identical coils placed diametrically opposite around the flywheel and two identical magnets (with identical poles sticking out) placed diametrically opposite on the flywheel.

partzman

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Re: AC voltage from single magnetic pole
« Reply #82 on: October 09, 2020, 08:33:21 PM »
You mixed the turns, voltage coil should have little turns, not vice versa.

Also you moved magnet by hand altho inductive reactance is undetectable at such low frequency.

It's funny how you try to prove he's right with resistive coils while doing the test wrongly forgetting he is making a claim for PURELY INDUCTIVE COIL.

Nix,

This test has L1 and L2 reversed.  IOW, L1 is now the current sense winding and L2 is the voltage sense winding.  The inductance of L1 is 143uH and the DCR is .38 ohms.  L1 is wound with 100 turns as stated before and is wound with 15-34 litz wire as is L2.

As one can see, the voltage and current are still in-phase.

How pure an inductive coil do you desire?  How about giving a desired L/R ratio?  IOW, at what point do we begin to see a phase shift towards 90 degrees current lag?

I am not favoring anyone here, I am interested in the science.

Regards,
Pm

nix85

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Re: AC voltage from single magnetic pole
« Reply #83 on: October 09, 2020, 08:39:29 PM »
Nix,

This test has L1 and L2 reversed.  IOW, L1 is now the current sense winding and L2 is the voltage sense winding.  The inductance of L1 is 143uH and the DCR is .38 ohms.  L1 is wound with 100 turns as stated before and is wound with 15-34 litz wire as is L2.

As one can see, the voltage and current are still in-phase.

How pure an inductive coil do you desire?  How about giving a desired L/R ratio?  IOW, at what point do we begin to see a phase shift towards 90 degrees current lag?

I am not favoring anyone here, I am interested in the science.

Regards,
Pm

Look at the vid i linked.

Makes you wonder if phase shift is 90° when he barely pushed it with hand, how much would it be at 1000 or 2000 rpm.

partzman

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Re: AC voltage from single magnetic pole
« Reply #84 on: October 09, 2020, 09:27:21 PM »
Look at the vid i linked.

Makes you wonder if phase shift is 90° when he barely pushed it with hand, how much would it be at 1000 or 2000 rpm.

Nix,

Are you sure you and the author of this video have interpreted the results correctly?  Here we see three coils spaced the same distance apart as the PMs in the rotor.  However, the first two coils relative to the rotational direction of the rotor, have their axis at 90 degrees to the PM axis while the third coil with the voltage sense coil have their axis in line with the PM axis.  Aren't we apples to oranges here?  The current phase in the first two coils at 90 degrees off-axis will be different that the third on-axis coil. 

Also notice the screenshot taken below that is early in the test, shows the current waveform more symmetrical around zero as compared to the shot you choose to use in the later part of the video.  In the screen shot below, the phase is not even close to 90 degrees but appears from dimensional measurement to be more like 56 degrees. 

In the scope pix you show taken at the later time in the video, the current waveform has shifted considerably upwards off center and does appear to be closer to 90 degrees.

Also, you criticized my frequency using the hand passed PM but this test has a half period of ~15ms where with my test the same half period is ~17ms!?

IMO, this video does nothing to confirm your position.

Regards,
Pm

nix85

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Re: AC voltage from single magnetic pole
« Reply #85 on: October 09, 2020, 09:37:20 PM »
Nix,

Are you sure you and the author of this video have interpreted the results correctly?  Here we see three coils spaced the same distance apart as the PMs in the rotor.  However, the first two coils relative to the rotational direction of the rotor, have their axis at 90 degrees to the PM axis while the third coil with the voltage sense coil have their axis in line with the PM axis.  Aren't we apples to oranges here?  The current phase in the first two coils at 90 degrees off-axis will be different that the third on-axis coil. 

I noticed first coil is at 90° and i attribute the votage ripple to it. Not an issue.

Quote
Also notice the screenshot taken below that is early in the test, shows the current waveform more symmetrical around zero as compared to the shot you choose to use in the later part of the video.  In the screen shot below, the phase is not even close to 90 degrees but appears from dimensional measurement to be more like 56 degrees. 

In the scope pix you show taken at the later time in the video, the current waveform has shifted considerably upwards off center and does appear to be closer to 90 degrees.

56? Are you kidding? In your screenshot current is barely above 0 when voltage is max, this is near perfect 90°.

Quote
Also, you criticized my frequency using the hand passed PM but this test has a half period of ~15ms where with my test the same half period is ~17ms!?

Already addressed that, i ascribe it to many more turns than you used.

Quote
IMO, this video does nothing to confirm your position.

Regards,
Pm

So, you're a joker. Good one.

nix85

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Re: AC voltage from single magnetic pole
« Reply #86 on: October 09, 2020, 09:41:16 PM »
In fact, it is not near perfect, it IS perfect 90° offset.


verpies

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Re: AC voltage from single magnetic pole
« Reply #87 on: October 09, 2020, 09:51:15 PM »
Resistance brings i-v into phase, but he claims they can be in phase in purely inductive circuit WITHOUT resistance.
Once again.. he claims they can be in phase in purely inductive circuit WITHOUT resistance.
Yes, that is what I claim when the inductor is energized magnetically. 
Also, I claim that this is true in inductive circuits WITH resistance when they are energized magnetically.
« Last Edit: October 10, 2020, 12:44:26 AM by verpies »

partzman

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Re: AC voltage from single magnetic pole
« Reply #88 on: October 09, 2020, 09:53:50 PM »
Nix,

When you look and compare the rising edge of the voltage waveform in red, as compared to the rising edge of the current waveform in yellow as compared to the overall current period that is yellow-yellow, the phase is about what I stated, not 90 degrees.  You are comparing the aberration in the voltage waveform to the peak in the current waveform which is not truly accurate.

Regards,
Pm


verpies

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Re: AC voltage from single magnetic pole
« Reply #89 on: October 09, 2020, 10:00:35 PM »
To at least approach these conditions with resistive wire, one has to use the method i gave above.
1. Separate coil to measure voltage.
2. Measure current with clamp probe.
3. AT LEAST 50 turns of thick wire.
I agree with these experimental conditions and add that:
a) the "open voltage coil" must not be in close proximity to the "closed current coil" because the latter distorts the flux from the magnet passing through the former.
b) the coils must be identical so no objections can be raised based on their differences.
c) the apparatus must be calibrated in such manner, that when both coils are open, then the voltage signals generated by them are identical and in-phase.