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Author Topic: Negative Inductance  (Read 42300 times)

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This also explains why a LCR meter reads negative inductance values sometimes, because negative inductance is capacitance, and therefore it means the meter is testing the inductor above it's self resonant frequency.

   

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Hmmm....

Never thought of Hz>SRF for L makes L into C.

I believe both C & L change over frequency. What does happen is Hz>SRF of L is where the coil capacitance becomes dominant, not that a coil becomes a capacitor.
When you start applying probe signals other than sine waves, like stepped pulses, things do become wild.

I don't like the use of "SRF" for this point anyway. The true SRF would have multiple points and types of resonance. The first being magnetostrictive and/or electro-physical resonance point. I call it the 'Slinky' point  :D The current use of SRF is fine for 'conventional' work  ;D

« Last Edit: 2010-11-09, 14:21:35 by Peterae »


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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   

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So – how do we get a negative inductance ?

Initially – this seems to be impossible:

passive, absolute, negative devices cannot be built in real life just like that, because they do not

comply with the conservation-of-energy-principle. Negative devices do not spend energy – instead

they would generate energy.

 ::)
« Last Edit: 2010-11-09, 14:21:50 by Peterae »
   

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Generate energy ONLY at a single specific frequency with voltage lagging current by 270 deg (specific frequency related to THE SRF being used - physical, electrical, etc.).

Such a network could become 'negatively under-damped' (not to be confused with over-damped).

>>>FWIW: a negative inductor would probably perform better with a core containing charge carrier capabilities vs a bundle of magnetic field lines  ;) Perhaps a non-ferrous conductor, capacitor, dielectric or conductive ring?

Yes, I have a few theories for coils.   8)

I'm likely finished trying to understand capacitors. I'll keep those results to myself to avoid flame wars. I'll just say someone asked my opinion of the work of Ivor Catts. Then, my impressions weren't very good. To date I find his work far more correct than the classic.

I'll re-write these observations(Laws) of physics later. Right now I'm testing an energy isolation system for my bench  ;D

 
« Last Edit: 2010-11-09, 14:22:05 by Peterae »


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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   

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One more thought then I must finish the testing....

Imagine the possibilities if you made your coil having physical resonance slightly above a subharmonic of classic SRF. Make it see this physical frequency, so it vibrates, twists, elongates, whatever, and placed a magnet near it. All this movement would cause classic induction, would it not?

My definition of the TK device: "The solution to the TPU heating problem"  ;D

« Last Edit: 2010-11-09, 14:22:20 by Peterae »


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"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   

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http://www.mogami.com/e/puzzle/pzl-04.html

The Mystery of Inductance of Lead Wire We sometimes see "inductance of lead wire" in Electrical Engineering technical books. For example, the following expression is found in a book titled "Analytical Noise Mechanism" by CQ Publishing Co. at its 120th page.

L = 2*l*(log(4*l/d)-3/4)   (nH/m)  (1)

where, L = inductance of lead wire (nH/m)
       d = diameter of lead wire  (cm)
       l = length of lead wire  (cm)

Before adapting the formula for circuit calculation, please see it carefully. There is something very inexplicable with it. First of all, it says that, because inductance of lead wire per unit length is L/l:

(1)  its inductance per unit length gets infinitely bigger as lead wire gets
longer and longer.

This does not make sense from the standpoint of physical science. It also says,

(2)  when the length of lead is a half of its radius, the inductance
becomes zero!

That sounds more strange, because, if that's the case, it will be possible to do wiring without inductance by connecting a small piece of cable of 1/2 the radius length in series. In addition, it says,

(3)   When the length of lead is less than the half of its radius,
inductance becomes negative figures.  As the length of lead gets to zero
closer and closer, the inductance approaches to negative infinite!!

If so, it enables to make a circuit of negative inductance. But, inductance is inertia against current and is circuit element which functions to prevent current alteration. Therefore, inductance in negative figures would help current alteration, which would enable the current to increase dramatically only by adding a little amount of current. That would lead to an amazing theory that a small piece of copper wire picked up from a garbage dump would solve the problem of the global energy crises. This, of course, is against one of the basic rules of physical science, the rule of Energy Preservation, and impossible to happen.

There is no explanation in the book about the basis of this formula, though I assume it is referred to the calculation by "Geometric Mean Distance"(G.M.D.) basing upon the Newmann's formula. For example, see in the 392th page of the classical famous book "Electromagnetics Phenomenon Theory" (Maruzen Publishing) by Setsuzo Takeuchi, where you will find the following formula:

L = (u0*l)/(2*PI)*(log(2*l/a)-3/4)   (H/m)  (2)
where, L = inductance of columnar conductor   (H/m)
a = radius of column   (m)
l = length of column   (m)
u0 = permeability (H/m)
PI = 3.14159265358979..

Since lead is a columnar conductor, the formulae (1) and (2) completely correspond each other in consideration of u0 being vacuous permeability (4* PI*1e-7 H/m).

In other words, the inductance of lead looks as if it has affirmative theoretical background, while believing in it may mean denial of the base of modern physical science. How can we understand this "inductance of lead?"
« Last Edit: 2010-11-09, 14:22:34 by Peterae »
   

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The Mystery of Inductance of Lead Wire We sometimes see "inductance of lead wire" in Electrical Engineering technical books. For example, the following expression is found in a book titled "Analytical Noise Mechanism" by CQ Publishing Co. at its 120th page.

L = 2*l*(log(4*l/d)-3/4)   (nH/m)  (1)

where, L = inductance of lead wire (nH/m)
       d = diameter of lead wire  (cm)
       l = length of lead wire  (cm)

Before adapting the formula for circuit calculation, please see it carefully. There is something very inexplicable with it. First of all, it says that, because inductance of lead wire per unit length is L/l:

(1)  its inductance per unit length gets infinitely bigger as lead wire gets
longer and longer.

This does not make sense from the standpoint of physical science. It also says,

(2)  when the length of lead is a half of its radius, the inductance
becomes zero!

That sounds more strange, because, if that's the case, it will be possible to do wiring without inductance by connecting a small piece of cable of 1/2 the radius length in series. In addition, it says,

(3)   When the length of lead is less than the half of its radius,
inductance becomes negative figures.  As the length of lead gets to zero
closer and closer, the inductance approaches to negative infinite!!

If so, it enables to make a circuit of negative inductance. But, inductance is inertia against current and is circuit element which functions to prevent current alteration. Therefore, inductance in negative figures would help current alteration, which would enable the current to increase dramatically only by adding a little amount of current. That would lead to an amazing theory that a small piece of copper wire picked up from a garbage dump would solve the problem of the global energy crises. This, of course, is against one of the basic rules of physical science, the rule of Energy Preservation, and impossible to happen.

There is no explanation in the book about the basis of this formula, though I assume it is referred to the calculation by "Geometric Mean Distance"(G.M.D.) basing upon the Newmann's formula. For example, see in the 392th page of the classical famous book "Electromagnetics Phenomenon Theory" (Maruzen Publishing) by Setsuzo Takeuchi, where you will find the following formula:

L = (u0*l)/(2*PI)*(log(2*l/a)-3/4)   (H/m)  (2)
where, L = inductance of columnar conductor   (H/m)
a = radius of column   (m)
l = length of column   (m)
u0 = permeability (H/m)
PI = 3.14159265358979..

Since lead is a columnar conductor, the formulae (1) and (2) completely correspond each other in consideration of u0 being vacuous permeability (4* PI*1e-7 H/m).

In other words, the inductance of lead looks as if it has affirmative theoretical background, while believing in it may mean denial of the base of modern physical science. How can we understand this "inductance of lead?"

I've created a monster!  :D

Good idea moving this to a separate thread. This is far deeper than most forums will go. Some will be lost down the rabbit hole.

Quote
When the length of lead is less than the half of its radius,
inductance becomes negative figures.  As the length of lead gets to zero
closer and closer, the inductance approaches to negative infinite!!

Try visualizing the above quote.... You wind up with a thin disc -or- one side of a capacitor -or- a one sided transmission line :o

Picture the phase relationship between current and voltage and how the time between current and voltage change (variation of power factor).

Try to imagine what may happen if the current leads voltage by more than 90 degrees. Could this result in a signal boosting its own propagation?


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"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   

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Indeed, i think some experimentation is required.

As for a lead disk, i wonder if anyone has thought about trying a lead homopolar generator.

I have a piece of lead somewhere, i will try cutting a small disk and see what the meter makes of it.

My main line of experimentation is to follow the negative inductance route and try to build a Flux-Capacitor  ::) oops that's already been done I Hope i dont lose too much time on that project  ;D
   
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Peterae:

I think there is a lot of misunderstanding in that link you quoted.  As an exercise, I would suggest that you do other searches to find the formula for the inductance of a length of wire because there is something that doesn't smell right.  The first place I would look would be the Hyperphysics web site.

Some comments:

Quote
L = 2*l*(log(4*l/d)-3/4)   (nH/m)  (1)

The units are screwed up.  The formula is for Henrys and then they put Henrys/meter in brackets.   There is no mention of the permittivity mu in the equation.

Quote
(1)  its inductance per unit length gets infinitely bigger as lead wire gets
longer and longer.

The formula appears to be for the inductance of a given length of wire, not for the inductance per unit length.  The guy's statement makes no sense.

Quote
In other words, the inductance of lead looks as if it has affirmative theoretical background

This guy is confusing "lead" as in a length of wire (the leads to your multimeter) with "lead" as in the metal.  That's the end of it right there, the link you quoted is pure junk.  It's so awful that I would not trust the second formula that looks more legitimate.

I strongly suggest that you do more searching to get the formula for the inductance of a length of straight wire.

MileHigh
   

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I think in every case where the word 'lead' is used it is to describe the wire, as in "radial lead" or "axial lead" of a capacitor, resistor, etc.

The other 'lead', the soft metal used to make bullets, is not part of the mystery or the posting.



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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   

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Ok MH thanks for pointing this out, my misunderstanding  :-[
   
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Whatever, then this is the link killer:

Quote
its inductance per unit length gets infinitely bigger as lead wire gets longer and longer.

You should run away from that link and get the information somewhere else.  I am not convinced that the author is not completely mixing up the two leads either.
« Last Edit: 2010-11-09, 19:13:59 by MileHigh »
   

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The web page by the apparent Japanese cable expert is posed as a puzzle, not a statement of fact.

As for inductance of unit length not changing regardless of the situation....

Well, all I can suggest is experimentation. I don't believe everything printed and don't suggest it.

Provide a resolution for the Riemann hypothesis and I'll start believing everything printed after that. If that isn't thought to be related, sorry I mentioned it.


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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   

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The lead page may well have been a red herring, but it only showed up because i was trying to find anomalies to do with negative inductance, the interest in negative inductance still stands

Now let me go and read about Riemann hypothesis  ;D
   

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tExB=qr
Expand "space".  i.e. reduce it's density.

Conservation of energy is not violated this way.

What does "negative inductance" do for you?

   

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The lead page may well have been a red herring, but it only showed up because i was trying to find anomalies to do with negative inductance, the interest in negative inductance still stands

Now let me go and read about Riemann hypothesis  ;D

Please don't  ;) I like just the way you are  :D The Riemann dZeta function is the explanation given to me by a well known institute for my magnet-dropping experiments. Riemann's works are keystones for so-called modern math but some say disagrees with Euclid. I have always disagreed with his fifth postulate.

Inductance and capacitance are said to be fixed numbers. If a capacitor measures 1F once it will always measure 1F except for extremes like something changing the properties of that capacitor (or inductor). The truth is, these measurements are based upon magnetic and dielectric reluctance. Reluctance is not fixed.

If you step-pulse a coil with the right time spacing between current steps the following pulse or change sees less reluctance. So, the following pulse sees less inductance, impedance, higher velocity factor, etc.

Even the NIST has some difficulty with this. It is known and even more known as we make use of higher intensity, frequency and variations of probe/test pulses.



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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   

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Negative Inductance circuit patent 1928

Quote
Page 2 75

Hence in such a circuit, if a number of e;ectromotive forces having different frequencies (instead of a single frequency electromotive force) were active, the reactance of the circuit would be uniformly zero for all frequencies as shown by Equation (4)
there would be no discrimination as between different frequencies. To put this in another way, we would have realized a distorionless circuit.

http://www.google.com/patents?id=pnNbAAAAEBAJ&printsec=abstract&zoom=4#v=onepage&q&f=false
   

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Ah yes.

One of the earliest, if not the first, examples of negative inductance using an active circuit. Everyone I know says this can only be done with active circuits.
So why does it show up just by hitting a coil with frequency just above SRF. Wouldn't a coil qualify as a passive circuit?
 


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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   
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...negative inductance is capacitance
...

Only at a specific frequency.

A negative inductance is not a capacitance, the frequency dependence of its impedance is not the same.

(I reply to this old post because I'm now studying negative inductance and capacitance).

   

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yes indeed ex sorry my explanation was too vague, anyone interested should know this of course as well.

A very interesting subject and worthy of further study  O0
   
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