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Old 8th May 2013, 08:27 PM   #39041
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Quote:
Originally Posted by simon7000 View Post
Tomorrow is a bench day. I will use a "high" value resistor and "DC" to feed a toroidal transformer and watch the voltage across the coil. I can do this with both polarities (phases actual since I am not immortal, alas.) The I can remove and reapply the same direction current and see the difference in time from starting with matching or opposing remnance.
How about watching inrush after magnetizing the core. Use DC to mag the puppy, then turn on the ac with a zero crosser in series with a big diode.

You'll only see the first 8 milliseconds or so, but you can correlate magnetizing level and direction to the first inrush pulse.

edit: you may need to provide another path around the toroid to keep the zero crosser happy, I would expect it requires some quiescent current to work properly.

jn

Last edited by jneutron; 8th May 2013 at 08:32 PM.
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Old 8th May 2013, 08:30 PM   #39042
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I don't think so. Everything I read confirms my view, that skin and proximity effect are essentially the same thing. You have yet to present a single peer-reviewed paper or standard textbook which supports your view.
As opposed to you, who has presented what exactly?
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That is an assertion which I believe is not supported by EM theory, which shows that the spatial current pattern is set by geometry, frequency and material properties only.
You keep saying theory proves...you haven't shown that.

You also have not explained away the 2f dependence example scott provided.

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Old 8th May 2013, 08:35 PM   #39043
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JN I plan do do the magnetization very slowly think seconds.

My math says when you have sine wave interacting with itself you have sin^2 and (sin(x))^2 + (cos(x))^2 =1 along with cos(2x) = 2(cos(x))^2 - 1 so second order products are a natural. Of course that is basic trig.
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Old 8th May 2013, 08:52 PM   #39044
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Quote:
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The simplest way to see this, as I have said many times before, is to recognise that Maxwell's equations both in free space and in linear media are linear equations. Therefore they cannot give rise to non-linearity. Provided the geometry is fixed (i.e. the wires don't move) there is no effect.

Anyway, I am repeating myself. I said I was not going to go through the argument again so I will stop here. This should not be regarded as an admission of defeat, except in the sense that I have been unable to convince you. The burden of proof rests on those who claim that the accepted EM theory taught in textbooks is wrong.
OK I'll stop too, the currents involved don't make testing this easy. In parting my electrostatic example requires no non-linearity at all, you can assume pure piston motion of the two plates with no suspension non-linearity and you still get pure second harmonic.

You probably were not around for the sound propagation in water thread. It ended on a happy note.
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Old 8th May 2013, 08:59 PM   #39045
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Quote:
Originally Posted by simon7000 View Post
JN I plan do do the magnetization very slowly think seconds.

My math says when you have sine wave interacting with itself you have sin^2 and (sin(x))^2 + (cos(x))^2 =1 along with cos(2x) = 2(cos(x))^2 - 1 so second order products are a natural. Of course that is basic trig.
shhh..math is not allowed..

Strictly mindless back and forth..that's the call of the day.

jn
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Old 8th May 2013, 09:04 PM   #39046
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Originally Posted by scott wurcer View Post
OK I'll stop too, the currents involved don't make testing this easy.
Maybe, maybe not.

Wind a toroid with a coax, multiple winding layers..drive only the shield with current.

The core voltage will be the exact same voltage as the shield voltage, minus the IR drop..so connect the core at one end of the coax, and look at the differential between core and shield at the other.

Any magnetic non linearity will show up on both shield and core, and they will cancel, leaving just the shield IR drop.

jn
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Old 9th May 2013, 01:43 PM   #39047
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Originally Posted by simon7000 View Post
JN I plan do do the magnetization very slowly think seconds.
Calculate the inductance referred to the primary. Then the no load current the core will pull. Know the number of turns.

Wind a secondary with sufficient amp turns such that you can drive peak flux into the core using a dc supply..

Use the DC coil to preset any arbitrary remnant field you wish to test. Magnetize it, then bang it with a controlled-on half sine.

Magnetize the core peak remnance in both directions w/rt the half sine charging impulse.

This is the testing regimen that will provide what we discuss.

As to the math...the proximity effect gets more interesting when you start introducing a lag in the magnetic field. Especially at a gapped core near the gap, the fields just go crazy there.

jn
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Old 9th May 2013, 04:06 PM   #39048
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On another subject of discussion, I find that I have a significant departure in concept and methodology from many 'critics' here, and this has gone on for a dozen years or more.
Yesterday, while sorting some papers, I found some print-out by me from 15 years ago on the internet, but another website. It was 1998 when I typed this commentary. I hope that I can show it here. If I can, then I would say that it is MY way of developing audio, beyond college training, 45 years of experience (only 30 when I wrote this) and what I still find 'works for me'.
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Old 9th May 2013, 06:25 PM   #39049
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Originally Posted by jneutron View Post
Maybe, maybe not.

Wind a toroid with a coax, multiple winding layers..drive only the shield with current.

The core voltage will be the exact same voltage as the shield voltage, minus the IR drop..so connect the core at one end of the coax, and look at the differential between core and shield at the other.

Any magnetic non linearity will show up on both shield and core, and they will cancel, leaving just the shield IR drop.

jn
OK, I'll try a wrap my blockhead around this (the email helps).
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Old 9th May 2013, 06:31 PM   #39050
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At the time of my 1998 comments, I was losing ground in audio. My designs were NOT getting good to excellent reviews, even though they used my topology, measured very well, had lots of features, and were cost competitive with just about anything else.
How can this be? It had MY name associated with the newer products, with all the product 'puffing' that marketing could conjure up, why did the reviewers find my latest designs (at the time) just OK, and nothing special? I will give you MY reason, why later or more independent designs actually were met with great success with reviewers and serious audio listeners, in general.

ATTENTION TO DETAIL, including parts,(both brand and construction), layout, and wiring.

Could any significant difference be measured? NO!
It had to be what we found WORKED better than something similar, and we used our ears to make the final evaluation, rather than just measurements, which were always pretty darn good. Take it or leave it, that has been my experience, and if I had not followed this path, I would not be in the audio business, today.
Heck, Parasound was ready to 'cut me loose' after a few 'failed' designs at that time. However, when we (CTC) showed, independently, that we could either completely develop, or modify Parasound products that were really subjectively successful, Parasound finally decided to give us a bit more freedom to design the JC series of Parasound products, and it has worked pretty well. To my knowledge, LESS advertising has been done by Parasound in later years, especially in magazines, YET we always get a good review, with the later designs that I have some design control over. That is my experience, and what I have tried to convey on this thread, is what we found important in audio design, above and beyond the schematic. Unfortunately, I am not able to do any better in this regard, at least on this website.
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