What about at no current? The mean and variance are measurable certainly if you can muster a 100 Ohms or more resistance of two widely different wire diameters. You might need auto correlation techniques if you want to go deep sub Hz 1/f.
A length of wire does not form a loop unless you specifically do so by moving it about.
When you have the wire delivered, I'll let you know how to do it, it's only 19 tons. .
jn
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You spool it up, we're talking DC noise for a start. You could do #40 vs #32 pretty easily.
A length of wire does not form a loop unless you specifically do so by moving it about.
When you have the wire delivered, I'll let you know how to do it, it's only 19 tons. .
jn
My standard loudspeaker wire is 2 conductor 10 gauge. It is 97 pounds per 1000 feet so 50 spools would be 100,000 feet at 4,850 pounds including the spools. But maybe gravity is higher where you are!
I probably have close to that on hand. Last shipment came in with another parked truck blocking my loading door and forklift so I am pretty sure of the weight.
This is where we don't communicate. 100 ohms at room temperature will show 1.3 nanovolts per root hertz. Why you think this will change with frequency, I don't get.
I expect variation on the signal's velocity of propagation in a non-homogeneous media.
A common saying is that "Electricity takes the shortest path." This is of course nonsense. Current takes all the paths proportional to the conductance. Conductance being the reciprocal of resistance as we all should know.
So my take is that in an imperfect conductor the signal would take different paths with different velocities of propagation hence slightly different arrival times and levels thus at the end of the conductor the effect would be to appear to have some noise added. When two sine waves are passed I would expect this process to yield a bit of the sum and difference signals that should also appear as noise at those frequencies.
My take is that at higher current levels things average out faster and appear smoother.
Now this would predict lower contamination conductors would pass signals better. It also would suggest things like silver plated wires would not, as there would be different propagation velocities in the two different materials.
Now my take that thicker conductors have more paths available might actually be happening according to my test results from that or the possibility that thicker conductors have more contaminants.
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Where did I ever say that? Frankly I'm tired of you making these statements of things I never said. I posted a reference today pointing out to Max that the noise was white i.e. no frequency variation for most cases. I'm sure you have no interest in the ample literature on these issues where 1/f noise in some situations can appear. Frankly I think your just making up a bunch of nonsense.
Why don't you just listen to jn, you are wrong.
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It actually is higher here..
Hey, I was only one decimal place off!!! Sheesh, ran outta fingers.
Magnet wire #10 is 38 lbs per kfoot.
Btw, prop velocity of a signal in a t-line is not dependent on mean free path of the electrons. Sorry.
Jn
Are you going to tell me propagation velocity doesn't change with material in a conductor?
In addition to the normal equation there is the relative permeability. Now copper is .999991 and silver is .99998.
So there should be a different velocity of propagation. Now what the impurities are and their permeability is I suspect no one really knows, but can offer a good guess.
Now just for giggles if a copper wire was formed by a steel die all bets are off as to permeability and uniformity. Good thing steel dies for wire forming are almost extinct.
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So it has reduced to me proving that your made up conjectures are not accurate???
I think not.
Show us some real science.
Show us some real tests.
Show us the evidence.
All you have done is show us a bogus test with a bogus conjecture,where environmental noise you are unable to control is 40 dB higher than some squiggle at 3 kHz.
You have absolutely no controls, you have no idea how your setup is dependent on shielding, loop currents, even simple resistivity of the conductors.
I know what real science is, what real physics is, what real engineering is... So far, you have not demonstrated any ability to control any test on this topic.
As I said, there are many here who can help you design a test, you really do need to ask for help. There are some here who are the best on this planet on this stuff, just ask.
Would you like to test some inductors for second order proximity effect modulation? If it produces positive results, the textbooks would actually have to be re-written.
Jn
I came across this relatively new part. Looks nice, but I saw this note in the Absolute Maximum Ratings table that I don't recall seeing before:
http://www.ti.com/lit/ds/symlink/ths3491.pdf
Continuous output current (3) +/-100 mA
(3) - Long-term continuous current for electro-migration limits.
Of course, they don't mention what long-term is. Is this atypical and due to process limitations for this part? I don't see the note on some of the other DSL line driver type parts.
http://www.ti.com/lit/ds/symlink/ths3491.pdf
Continuous output current (3) +/-100 mA
(3) - Long-term continuous current for electro-migration limits.
Of course, they don't mention what long-term is. Is this atypical and due to process limitations for this part? I don't see the note on some of the other DSL line driver type parts.
If your are using a complex stimulus (aka music) and demand from your test subjects a multidimensional evaluation, expect up to 80% false answers. I´m sure i´ve cited the literature already in other threads so just a short summary.
This phenomenon was already noticed in 1980 with cigarettes, later in audio tests and in food tests as well.
Even a multinational experiment was done (food) and showed that it is a crossnational thing, although the propotion of false answers varied between the nations.
Are you saying that resistance varies with current? If so, an awful lot of small-signal apparatus would cease to work.simon7000 said:
How did you heat it? Was it all at exactly the same temperature? If not, have you heard of the thermoelectric effect?
Thermal noise. White.
Excess noise, may be 1/f, may not appear at all. I'm sure I read somewhere that metals don't have significant 1/f noise.
You need to define what you mean by 'velocity of propagation'. Then maybe someone will try to explain it to you yet again.
You need to think about orders of magnitude and timescales. Ordinary scattering produces resistance, which is linear over a huge range of current densities and also constant over a huge range of frequency. Resistance produces thermal noise. To see your postulated effect you will need to look well below thermal noise, to see the noise modulated by the signal. Thermal noise in a wire is tiny, so your postulated signal will be much smaller than tiny. My guess is that experimental error will be much greater than the effect you are looking for, so the effect will be invisible even if it exists.
I am fairly certain your take is wrong. I am fairly certain that your experiments will not see the effect you are looking for. I am fairly certain that your experiments will see something, but then others will tell you what you are seeing: ordinary experimental errors.
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