Yes, I was aware that it might not be a direct measurement of skin effect. However, this is where skin effect would start to show itself as the source paper indicates.
There is really nothing to show... an osc into an amp driving a coil. A sensitive voltmeter is connected to the other (receiving) coil. Metal is placed between coils.
It is also useful to indicate relative shielding effectiveness of various metals and thicknesses. vs freq.
THx-RNMarsh
Source---
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Thanks.
What needs clarity is definitions.
Skin effect in a wire discussion is detailing the exclusion of current from the center of the wire as a consequence of faraday's law of induction, as caused by the current within the conductor.
Skin effect in a surface discussion is eddy currents generating magnetic fields in direct opposition to time varying magnetic flux trying to penetrate the surface from an external source. This is what your measurement is doing.
My inductance measurement of coils in air and against copper demonstrate the way copper will exclude dB/dt by eddies, which lowers the total energy stored in the magnetic field. My test also shows how the meter reads the eddy losses only as Rs.
My inductor sweeps show the inductance breakpoint at 10 kHz in air, this due to proximity effect. It shows also the break at 1 kHz when the clad copper is against it. Neither should be attributed as "skin effect" per se as that tends to reinforce misunderstandings that skin effect plays a huge role at audio frequencies in single or paired conductors. Since magnetic energy storage (inductance) goes as the square of turns in a coil, even a coil with 100 turns can show proximity (skin) losses that are measurable as the enhancement over a single conductor is four orders of magnitude.
As a shielding test, it's great.
John
Ps. Stung on the eyelid??? Really??? What bee stings you on the eyelid? Sigh... Go ahead, keep piling it on....
What needs clarity is definitions.
Skin effect in a wire discussion is detailing the exclusion of current from the center of the wire as a consequence of faraday's law of induction, as caused by the current within the conductor.
Skin effect in a surface discussion is eddy currents generating magnetic fields in direct opposition to time varying magnetic flux trying to penetrate the surface from an external source. This is what your measurement is doing.
My inductance measurement of coils in air and against copper demonstrate the way copper will exclude dB/dt by eddies, which lowers the total energy stored in the magnetic field. My test also shows how the meter reads the eddy losses only as Rs.
My inductor sweeps show the inductance breakpoint at 10 kHz in air, this due to proximity effect. It shows also the break at 1 kHz when the clad copper is against it. Neither should be attributed as "skin effect" per se as that tends to reinforce misunderstandings that skin effect plays a huge role at audio frequencies in single or paired conductors. Since magnetic energy storage (inductance) goes as the square of turns in a coil, even a coil with 100 turns can show proximity (skin) losses that are measurable as the enhancement over a single conductor is four orders of magnitude.
As a shielding test, it's great.
John
Ps. Stung on the eyelid??? Really??? What bee stings you on the eyelid? Sigh... Go ahead, keep piling it on....
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Yes, it might have that effect on some readers. But we know it is rather minor and not first order atten cause. OTOH, high-end would possibly consider it and try to minimize it also.
It does come into affect in the audio range of freqs. which is what i wanted to know/establish.
Next, I want to know its phase shift and how it (Skin signal) can effect signal integrity compared with lower freqs in typical audio apps... pcb, wire, cable. Such might occure in music fund vs harmonics.
THx-RNMarsh
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Sure that it isn´t you who is flailing?
Lets see, first you was sure that the "BBC dip" was an internet lure and therefore Jakob´s bad....
Then you was sure (by citing from the Harbeth site) that it wasn´t just an internet lure but was only used to correct for membrane resonances, but of course it was still Jakob´s bad.....
Then you insisted that jakob2 did wrote that every BBC speaker (or at least some) but couldn´t provide a cite to back up your assertion, but of course it was still Jakob´s bad.....
And now you are sure, that it was just an invention of the audio press, because Jakob "couldn´t find _any_ speaker" that displays it, and of course now it is really Jakob´s bad......
In fact there are a lot of speakers to find that display this sort of dip and apparently a lot of loudspeaker guys coincide wrt meaning of the phrase "BBC dip" and even some correction software does include it at least as an option.
And poor Jakob did several times explain that he used the phrase "BBC dip" just as a descriptor for a certain departure from linear frequency response, but of course it must be Jakob´s bad......
It´s quite simple to avoid something like that- please stop trying to put words in my mouth.....
Somewhat related to that, I just read that a Polish researcher
experimented with hiding information by deliberately modulating the rhythm of
dance music. It seems that 2% are perfectly tolerable. And he switched it dynamicaly.
Stegano-audio?
Sorry, in German:
< Steganographie in der Disko: Trance-Musik mit versteckten Daten | heise online >
regards, Gerhard
jneutron Gallery - My Photo Gallery
Hopefully that gets you there. As an FYI, Mods/forum managers, it's nigh impossible to get to galleries without hunting around.
Hopefully that gets you there. As an FYI, Mods/forum managers, it's nigh impossible to get to galleries without hunting around.
jneutron Gallery - My Photo Gallery
Hopefully that gets you there. As an FYI, Mods/forum managers, it's nigh impossible to get to galleries without hunting around.
Thanks. I see he actually meant hear.
Yeah, we know, we know. Some day in the future we will move to new forum software and all will be sparkly clean and beautiful.As an FYI, Mods/forum managers, it's nigh impossible to get to galleries without hunting around.
And FWIW, I did post a link to it right away.
http://www.diyaudio.com/forums/loun...ch-preamplifier-part-ii-8747.html#post4813999
Small thanks I got.
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