Hi Sully,
That is a very interesting site. I see what you mean about whew, that guy has either cribbed a lot from other sources or has spent way too much time thinking about this.
I'd like to explore what impact reducing self inductance at higher frequencies might have. Inductive impedance increases with frequency.
Zr = 2 * PI * Hz * L
This means that the reduction in self inductance as frequency increases (due to skin effect) will counteract the impedance increases at higher frequencies due to self inductance. This should have a linearizing effect on the frequency response of the wire. At low frequencies the reactive impedance is very low no matter how high the self inductance might be and at higher frequencies the reactive impedance is again very low because the self impedance is reduced to zero due to skin effect. In this example, skin effect is a good thing.
I don't see how there could be a change in stored energy due to this. For any given frequency, the self inductance is not changing.
Am I missing anything in this?
Phil
That is a very interesting site. I see what you mean about whew, that guy has either cribbed a lot from other sources or has spent way too much time thinking about this.
I'd like to explore what impact reducing self inductance at higher frequencies might have. Inductive impedance increases with frequency.
Zr = 2 * PI * Hz * L
This means that the reduction in self inductance as frequency increases (due to skin effect) will counteract the impedance increases at higher frequencies due to self inductance. This should have a linearizing effect on the frequency response of the wire. At low frequencies the reactive impedance is very low no matter how high the self inductance might be and at higher frequencies the reactive impedance is again very low because the self impedance is reduced to zero due to skin effect. In this example, skin effect is a good thing.
I don't see how there could be a change in stored energy due to this. For any given frequency, the self inductance is not changing.
Am I missing anything in this?
Phil
skin
A dc current within a wire will have the normal inductance..If it was a zip, there'd be stored energy related to that inductance.
Now, drop the current to zero in 1 microsecond..using a sine type drop, so 1 microsec is 90 degrees of the sine..that is a 4 microsecond cycle, 250 Khz.
From standard theory, 250Khz cannot go deep into the wire. So, that theory says the current in the middle of the wire cannot go to zero that fast..
Unfortunately, that is not what happens in reality..it is certainly possible to turn the current off that fast.
When the current is dropping, the current density profile move outward, consistent with hf signals on the wire..
When the current is shifting out to the surface, the self inductance dynamically drops to zero..
Is the energy of the dc self inductance used to re-distribute the current density, or does it manifest as an end voltage thing, phase shifting the hf..
A dc current within a wire will have the normal inductance..If it was a zip, there'd be stored energy related to that inductance.
Now, drop the current to zero in 1 microsecond..using a sine type drop, so 1 microsec is 90 degrees of the sine..that is a 4 microsecond cycle, 250 Khz.
From standard theory, 250Khz cannot go deep into the wire. So, that theory says the current in the middle of the wire cannot go to zero that fast..
Unfortunately, that is not what happens in reality..it is certainly possible to turn the current off that fast.
When the current is dropping, the current density profile move outward, consistent with hf signals on the wire..
When the current is shifting out to the surface, the self inductance dynamically drops to zero..
Is the energy of the dc self inductance used to re-distribute the current density, or does it manifest as an end voltage thing, phase shifting the hf..
Clearly, all radio- audio- engineers greatly underestimated the effect of skin-effect (sorry for tautology) for many years.
The problem: if you will calculate the skin-effect for PURE SINE SIGNAL by classic formula, you got nothing - very small impact to a signal, very thin area for audio frequencies.
But if you take into account Ageev's theorem (Ageyev's theorem in russian literature), you will see that:
1). musical signal with many harmonics can contain the areas with extremely high gradient (usually called "slew rate" in electronics).
2). Therefore for the poly-harmonic signal you have to MULTIPLY skin-effect by a factor of 10...100, and this is changing everything.
3). The skin effect is one of the main source of "solid-state sound".
I have invented in 1996-1997 very simple and very inexpensive method for supressing skin-effect in ANY WIRE: in cables, PCB, transistor etc. Later I wrote an article for russian audiophile magazine "Class-A".
THE PATENT HAS EXPIRED.
THIS INFO AND THE INVENTION IS PUBLIC DOMAIN NOW.
(I am a sole author).
Спосіб виконання струмопровідного елемента — UA 45352
In short:
1). replace the insulator of a cable by 5-20 layers of VIDEO CROME (CrO2) MAGNETIC TAPE from VHS casette.
2). thats it.
The reprints of patent and article about this method in russian Internet:
"Поверхностный эффект не терпит поверхностного отношения"
publication date May 1, 1997 publication description "Class-A" magazine
Skin-effect in high-end audio cables.
Usage in high-end audio cables:
Поверхностный эффект не терпит поверхностного отношения
Поверхностный эффект не терпит поверхностного отношения << схемопедия
-. ,
Поверхностный эффект не терпит поверхностного отношения
http://mainkas.tripod.com/page/samodel/cable/samodel1.htm
(I am not related to any of these publications).
How it works:
The paramagnetic layer on VHS cassette has permeability of about 2...5. This means that IT REFLECTS the skin-effect moves BACK INTO wire (cable), thus supressing the skin-effect. And it does this without supressing high frequencies of a signal. The cables are absolutely neutral in sound, without any distortions. Russian audiophiles are very pleased with them. The cost is near zero.
The patent also desribes the inverse usage of a method - for supressing high frequencies. Now it is used in Russia for high voltage high power electric lines.
Ph.D. Thesis in russian Novosibirsk University:
http://www.nstu.ru/files/dissertations/ilyushov_nya_1405669508.pdf
see my web-site for other details.
Funny: one guy in USA tried to patent it in USA much later, but that patent application later dropped, probably by a sitation of may patent by patent examinator.
Skin effect patent: US20120125651A1
https://patents.google.com/patent/US20120125651
The problem: if you will calculate the skin-effect for PURE SINE SIGNAL by classic formula, you got nothing - very small impact to a signal, very thin area for audio frequencies.
But if you take into account Ageev's theorem (Ageyev's theorem in russian literature), you will see that:
1). musical signal with many harmonics can contain the areas with extremely high gradient (usually called "slew rate" in electronics).
2). Therefore for the poly-harmonic signal you have to MULTIPLY skin-effect by a factor of 10...100, and this is changing everything.
3). The skin effect is one of the main source of "solid-state sound".
I have invented in 1996-1997 very simple and very inexpensive method for supressing skin-effect in ANY WIRE: in cables, PCB, transistor etc. Later I wrote an article for russian audiophile magazine "Class-A".
THE PATENT HAS EXPIRED.
THIS INFO AND THE INVENTION IS PUBLIC DOMAIN NOW.
(I am a sole author).
Спосіб виконання струмопровідного елемента — UA 45352
In short:
1). replace the insulator of a cable by 5-20 layers of VIDEO CROME (CrO2) MAGNETIC TAPE from VHS casette.
2). thats it.
The reprints of patent and article about this method in russian Internet:
"Поверхностный эффект не терпит поверхностного отношения"
publication date May 1, 1997 publication description "Class-A" magazine
Skin-effect in high-end audio cables.
Usage in high-end audio cables:
Поверхностный эффект не терпит поверхностного отношения
Поверхностный эффект не терпит поверхностного отношения << схемопедия
-. ,
Поверхностный эффект не терпит поверхностного отношения
http://mainkas.tripod.com/page/samodel/cable/samodel1.htm
(I am not related to any of these publications).
How it works:
The paramagnetic layer on VHS cassette has permeability of about 2...5. This means that IT REFLECTS the skin-effect moves BACK INTO wire (cable), thus supressing the skin-effect. And it does this without supressing high frequencies of a signal. The cables are absolutely neutral in sound, without any distortions. Russian audiophiles are very pleased with them. The cost is near zero.
The patent also desribes the inverse usage of a method - for supressing high frequencies. Now it is used in Russia for high voltage high power electric lines.
Ph.D. Thesis in russian Novosibirsk University:
http://www.nstu.ru/files/dissertations/ilyushov_nya_1405669508.pdf
see my web-site for other details.
Funny: one guy in USA tried to patent it in USA much later, but that patent application later dropped, probably by a sitation of may patent by patent examinator.
Skin effect patent: US20120125651A1
https://patents.google.com/patent/US20120125651
No. Radio engineers are well aware of it. Audio engineers often ignore it, but they are right to do so as it will be negligible in almost all cases.Alex Ra said:
Skin effect is a linear phenomenon so the principle of superposition applies. You can calculate the skin effect for different frequencies (whether harmonic or not) separately and just add up the results. Fourier was right all along!
What is the Russian for snake oil?
Where did in universe You find the word "linear"?
All formulas, figures and pictures about skin-effect ARE NON-LINEAR, even in simplest wikipedia:
Skin effect - Wikipedia
Have you ever seen a kinescope? With huge inductors to focus and to move the electronic beam? I REPEAT - TO FOCUS?
Deflection yoke - Wikipedia
The electrons spread far from each other - if run with acceleration (as in alternating current), without focusing.
Any alternating current is non-linear by its nature - because ELECTRONS DONT LOVE EACH OTHER.
Skin-effect is just one realization of this nature's feature.
My invention - is just a focusing paramagnetic shield around accelerating electrons, like in kinescope.
Sorry, I can not provide more simple explanation.
Actually, the deflection coils on a crt can only steer the beam, they cannot focus the beam. They are dipoles with a somewhat uniform field and the charged particles take a circular path in that field, deflected as it were.
Focussing of a particle beam with magnets is not that simple. For example, an alternating gradient synchrotron alternates focus and defocus quadrupoles with sextupoles to focus the beam.
Edit: just revisited the wiki skin effect page. It has progressed very significantly since I last looked.
However, nothing in it supports your arguments. But now I don't have to provide any of my that material anymore on forum, I can just say look at wiki.
Jn
Last edited:
Thank you for clarification. Yes you are 90% right - as for TV kinescope. But I have seen many computer kinescope monitors where the coils were used as a partly, secondary focusing tool, with the corresponding trim resistors on PCB on back of them. Focusing in computer monitors were not straight that simple. I dont exactly know how it was realized. I have spent 7-10 years as a chief SOFTWARE (well, hardware too) engineer of computer company (ies) and have seen thousands of computers and monitors. Besides, I worked in NJ.
But this is slightly outside the topic's matter, so personally I will not dig into this any deeper.
Do you see any discrepancy with what you know in electronics and my invention?
Thanks.
Deviation from Ohm's Law
From about 1921 it was known that Ohm's law depends on the current density and is becoming non-linear with high current density. High power electricians use this "feature" every day.
Here one example
"Measurement of the deviation from Ohm's law in metals at high current densities." 1921.
Measurements of the Deviation from Ohm's Law in Metals at High Current Densities | PNAS
View attachment 299.full.pdf
Musical signal is a kind of high-current, again due to numerous harmonics in it.
Maxwell equations are non-linear too. See wikipedia.
Ohm's law is for school.
From about 1921 it was known that Ohm's law depends on the current density and is becoming non-linear with high current density. High power electricians use this "feature" every day.
Here one example
"Measurement of the deviation from Ohm's law in metals at high current densities." 1921.
Measurements of the Deviation from Ohm's Law in Metals at High Current Densities | PNAS
View attachment 299.full.pdf
Musical signal is a kind of high-current, again due to numerous harmonics in it.
Maxwell equations are non-linear too. See wikipedia.
Alex, I believe you are mixing convergence mechanism with deflection and focusing. Focus was adjusted varying the the focus voltage of the focus anode, mainly in the HVT transformer. Convergence is a modulation of the horizontal defection current with vertical parabola to compensate the non-spherical front of the CRT. Deflection scans the front of the CRT.
Nope, I am not. Sorry if I misled you on this matter.
Sure, in my life I have dissambled a dosen of old oscilloscopes with no magnetic convergence/focus coils at all. Clearly, I know the difference. Focusing in TV, monitors and oscilloscopes are provided MAINLY by static plates or similar means. Focusing in my method is provided by static paramagnetic shield around the wire. This is a not important difference as for the core of a anti-skin method. And this is irrelevant to skin-effect in wires. I wrote about focusing just for an ANALOGY, in order to simplify the understanding of the method.
Good question.
The answer: Automatically.
It reflects the spreading of electron AUTOMATICALLY, without any calculations/compensations/resistors/capacitors etc. Paramagnetic shiled should be of CrO2 - the best, - or ANY paramagnetic ("ferrite" with low permeability) material. VHS tape has permeability of 1.5...2.0.
As a reuslt the capacitance of a cable INCREASES and the inductance DECREASES. The high frequency limit of cable line is expanding higher, from 15...30 MHz for expensive consumer-grade audio cable up to 150 MHz.
Just roll your wire into VHS tape.
Sounds idiotically, but it works.
Besides, the VHS tape made from polypropylene, which is one of the best insulator itself, used in audiophile capacitors.
Yes, exactly, but I do not recommend it. Ferrite beads usually have lowest permeability of 10...20. I think this is too high even for audio frequencies. It will supress higher frequencies, acting as an inductor - with input cpacitance of the next stage. (As we speak about interconnect cable).
OK. A question I never can clarify about skin effect, is what happen to it when:
a) Only AC is present in the wire (The common text in books),
b) DC + AC when the AC ptp amplitude is larger than AC (Then reversal of polarity, but asymmetrical);
c) The same as b, but the AC amplitude lower than DC (No reversal, but variable DC levels).
Your opinion?
a) Only AC is present in the wire (The common text in books),
b) DC + AC when the AC ptp amplitude is larger than AC (Then reversal of polarity, but asymmetrical);
c) The same as b, but the AC amplitude lower than DC (No reversal, but variable DC levels).
Your opinion?
No, Litz wire alleviates the effect of skin and proximity effects, but not cancel it. What this guy suggest is a kind of cancellation of the effect thanks to magnetic effects. I am not really completely convinced, but let the guy the opportunity to say us what he discover. It may be really novelty.
In fact Litz wire puts as many resistances in parallel as strands you use, but in each of them, problem continues to exist.
In fact Litz wire puts as many resistances in parallel as strands you use, but in each of them, problem continues to exist.
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