Pickling is usually used to remove the oxide film that is created when the material is annealed to reform its mechanical properties.
My Father briefly worked in a wire rope factory after he graduated. The pickling tank was made of Iron Wood sawn logs held tight with hastelloy bolts, the pickling solution was hot aqua regia. The neighbourhood used to get their washing on the line falling apart from the fumes.
And on a smaller scale I have used sulphuric acid and electrolysis to remove burrs from 316 stainless capilliary tubing.
Wrinkle
My Father briefly worked in a wire rope factory after he graduated. The pickling tank was made of Iron Wood sawn logs held tight with hastelloy bolts, the pickling solution was hot aqua regia. The neighbourhood used to get their washing on the line falling apart from the fumes.
And on a smaller scale I have used sulphuric acid and electrolysis to remove burrs from 316 stainless capilliary tubing.
Wrinkle
Nah, that'd be too easy...
The transatlantic cable problem was one of propagation velocity vs frequency. It was found that the velocity of audio frequencies on the long lines was variable enough to cause lots of distortion. By increasing L, it was possible to diminish damping..
They also found that the minimum damping was reached when:
Rsqr(C/L) equaled Gsqr(L/C).
This made the wave velocity independent of frequency..
Cheers, John
ps..I cheated..
Becker, Electromagnetic Fields and Interactions, 1964, page 262..
pps..hey, at least I remembered it was there...I get points for that, no??
It wasn't they, it was Oliver Heaviside.
John
Oliver whooviside??
Yo...gimme a break, all I got's is dis stinkin book by Becker...whaddyawant from me anywhoo..???
Cheers, John
Nah, that'd be too easy...
The transatlantic cable problem was one of propagation velocity vs frequency. It was found that the velocity of audio frequencies on the long lines was variable enough to cause lots of distortion. By increasing L, it was possible to diminish damping..
They also found that the minimum damping was reached when:
Rsqr(C/L) equaled Gsqr(L/C).
This made the wave velocity independent of frequency..
Cheers, John
ps..I cheated..
Becker, Electromagnetic Fields and Interactions, 1964, page 262..
pps..hey, at least I remembered it was there...I get points for that, no??
Whoo,
At least you did reveal what G means. Next you will give out the secrets of "repeat" coils and constant loading.
Right now we have almost anyone able to draw a schematic and simulate results. If we reveal the basics in the historic context, quoting papers anyone can follow, it will give THEM the well rounded context to actually understand not just what happens but why.
Look the purpose of this thread is to poke fun at JC when he tells people what has worked for him in the past and for him to explore options without having to reveal exactly what he is working on. If you, Scott & SE keep giving away the hidden secrets, that will reduce the venom often shown here, and things might get cleanly technical. As we all know that means boring.
Pavel, Demian, Bob, Jan, etc at least you haven't leaked any real secrets here.
ES
This is truely silly we always agreed. Now if only you would buy into the fact that an inductor in a box would have self noise commesurate with the eddy current losses.
I mean arguing in the technical sense, not the emotional sense!jneutron said:
Your last sentence of the quote shows that we still differ. You may not realise it, but you are holding two contradictory positions. First, you accept that there will be eddy current losses when a signal is present - this requires an additional resistance to appear in series with the winding resistance. You accept that this extra resistance is measurable, in the sense that it simply adds to the measured winding resistance (although measurement will not distinguish the two). You accept that the total measured resistance will generate thermal noise. All consistent to this point. Secondly, you deny that the eddy current mechanism will couple to the winding in the absence of a signal so the extra resistance will simply disappear when no signal is present. (It must disappear, on your point of view, because it was only the eddy current mechanism which created it but you believe this mechanism is only active when a signal is present. You say that resistance is only from the winding.) So you have a disappearing resistance, which is there when you measure it and can generate noise, yet disappears when there is no signal. Can you see the inconsistency in this? Have I misunderstood your position?
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I would expect them both to rise with frequency. The winding resistance slowly, core losses faster. Any HF resonance, due to stray capacitance, would speed up the rise towards the upper end of the audio band. These rises are purely because the resistance rises with frequency.
Note that thermal noise is white (constant with frequency) only when the resistance is independent of frequency. That is not the case here.
Note that thermal noise is white (constant with frequency) only when the resistance is independent of frequency. That is not the case here.
No, I did not reveal what G means....gotcha..
I've not yet read the paper linked, but I did find reference to the transatlantic cable and mu metal...what a fascinating read on some vendor site. For a while, the largest user of mu metal was just for these cables.. They mentioned the seawater (but not G)and capacitance which required the mu, so cool..(I was looking for a technical explanation for the rising mu on that graph that jlsem provided..thank you for that, I was not aware of this effect, and I needs ta understand it...)
Um, scott...it was just a recap...
Now if only you would buy into the fact that an inductor in a box would have self noise commesurate with the eddy current losses.
I still don't buy into that...and I'll explain why..
Eddy currents are caused by the rate of change of current within a coil causing a rate of change of flux within the core.
If I wish to measure the noise at the terminals of the inductor, and do so by connecting a meter widgit with input impedance of 10 power 7 ohms, I will not be forcing current into the coil.
So where would the eddy losses come from? no current, no flux, no rate of change of flux, no eddies.
Ah, good...it's fun arguing with you then..
note: I tossed my blue text comments within your quoted verbage just to keep it more consistent.
If there is no primary current, there is no net flux in the core. No net flux, no rate of change of flux. No rate of change of flux, no eddies. No eddies, no eddy losses.
To accept what you are saying, a mechanism which is capable of eddy current dissipation without any current flowing through any of the terminals MUST be present.
Yup. Violent agreement in the midst of argument..
Fun..and a pleasure.
Cheers, John
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