Could there be partial semi conductor boundries? Just be wrong in what causes them or where they come from?
THx-RNMarsh
THx-RNMarsh
Yes. The skin effect relies on eddy current loops being formed by the rate of change of transport current within the wire. A badly oxidized stranded conductor will begin to act like litz wire, where the self inductance of the wire (normally 15 nH per foot) will no longer decrease with frequency. A really badly corroded wire will not skin, so will retain it's inductance, whereas a good wire will lose the 15 nH per foot.
The really big point is, how much noise is generated by the eddies attempting to flow across poor contacting boundaries, and if the level of effect can be spotted in the noise of the conductor transport current.
No....in the words of that wise sage, Bill Murray.....Blowed up, sir...
jn
What happens if you have wire that is either extruded or pulled, one has strae alone its axis, te other radially and normal to the axis. then it oxidizes? dont to have a semiconductor ot capacitive boundy in the path of the signal?
Besides the inductance change with oxidated wires ---- there is the known break-thru voltage to penetrate an oxide contact/layer....... it varies with the metal oxide type but can be tenths of a volt..... depends also on oxide thickness, of course... but this breakthru voltage or jump will create noise and distortion.
So I wonder if people are comparing affects of oxidated wire and new fresh non oxidated wire and if solid or starnded?
THx-RNMarsh
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Any strand to strand radial nonlinearity which alters the lenz effect can in principal alter the overall internal inductance in a non linear fashion. (circumferential non-linearities will not do so as the time varying gradient is not circumferential by nature, just radial).
To find it, one has to be able to measure the internal inductance at the 1 nH per foot level during the attempt to skin. To attempt that, one has to account for the inductance of the return conductor's location in space with respect to the wire under test, and consider how to eliminate the proximity effect that return conductor will produce in the wire under test. A return cylindrical conductor will have it's own 15 nH per foot inductance, it will cause 150 nH per foot wire to wire inductance as well.
To properly remove the other conductor, the return path has to be a copper braid shield placed over the wire under test. The inductance of this system will be limited to the wire under test plus the inductance caused by the insulation thickness of the wire under test holding the braid from the core wire. The braid shield's internal inductance of 15 nH per foot will be divided by it's aspect ratio. If it is comprised of 100 strands of fine gauge wire, it's aspect ratio will be 100:1 and it's internal inductance will be 150 picohenries per foot.
If you select an insulation of 2 to 3 mils thick, you'll have about 10 to 20 nH per foot coaxial inductance, no braid internal inductance, no external inductance...so the problem becomes one of looking for a few nH change in a package of about 30 nH.
No, they are not.
jn
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So at what frequency does 3nH change come into play ? I would venture unless there is a RF issue not a lot then at least in the audio spectrum at normal loads . Help me with this please. 😱
I took a copper ribbon and connected it to my "Solder Joint Tester" The readings before and after heating it with a propane torch to form a very nice oxide layer were unchanged after it cooled down.
I believe that there were enough oxides formed that if such an effect were to occur it would have shown up.
I believe that once the connection has broken through it remains until disturbed or corrosion penetrates. Its not a continuous action on every AC/DC cycle. The virtue of gold on connectors is that it resists corrosion preventing (delaying, depending on your time scale) the decay of the connection over time.
If you look up copper oxide you will find it more complex. It needs to be doped with specific impurities to work. Metal rectifier - Wikipedia, the free encyclopedia Rev. Mod. Phys. 23, 203 (1951) - The Copper Oxide Rectifier and still more you never wanted to know: http://www.tubebooks.org/file_downloads/selenium.pdf And reading about what it takes to make a copper rectifier The H.P. Friedrichs (AC7ZL) Homepage its far from what would happen even in a stranded wire exposed to the elements (not jacketed).
While its not impossible for a wire to have copper oxide rectifier action between its strands, it seems pretty remote without active intervention. Perhaps someone can take some strands, follow the instructions and make a wire that has real diode surfaces and see if it makes a difference.
If it sounds better I'll be at the patent office before you. . .
If you look up copper oxide you will find it more complex. It needs to be doped with specific impurities to work. Metal rectifier - Wikipedia, the free encyclopedia Rev. Mod. Phys. 23, 203 (1951) - The Copper Oxide Rectifier and still more you never wanted to know: http://www.tubebooks.org/file_downloads/selenium.pdf And reading about what it takes to make a copper rectifier The H.P. Friedrichs (AC7ZL) Homepage its far from what would happen even in a stranded wire exposed to the elements (not jacketed).
While its not impossible for a wire to have copper oxide rectifier action between its strands, it seems pretty remote without active intervention. Perhaps someone can take some strands, follow the instructions and make a wire that has real diode surfaces and see if it makes a difference.
If it sounds better I'll be at the patent office before you. . .
Canyoncruz,
I'll assume if you are working with both toxic gases and toxic metals you have a very good understanding of the health and environmental factors with working with those types of material. I have been working with Brush Wellman/ Materion with Be domes for dome tweeter applications. These are foils and much less of a problem compared to the vapor deposition materials as used by TAD/Pioneer. In failure mode the Brush Wellman foil will normally only fracture and not release particles into the air while the vapor deposited materials are very likely to dissipate or release a few nasty particles into the air. There are many uses of Be/copper in electrical applications but in those instances the Be is tied up in the metal matrix but I still don't think you would want to machine those materials.
I just don't want people to think that you can freely handle or process Be without proper training or environmental controls. I've already been exposed to enough hazardous materials in aerospace, I surely don't need to add to that Be into my lungs.
I'll assume if you are working with both toxic gases and toxic metals you have a very good understanding of the health and environmental factors with working with those types of material. I have been working with Brush Wellman/ Materion with Be domes for dome tweeter applications. These are foils and much less of a problem compared to the vapor deposition materials as used by TAD/Pioneer. In failure mode the Brush Wellman foil will normally only fracture and not release particles into the air while the vapor deposited materials are very likely to dissipate or release a few nasty particles into the air. There are many uses of Be/copper in electrical applications but in those instances the Be is tied up in the metal matrix but I still don't think you would want to machine those materials.
I just don't want people to think that you can freely handle or process Be without proper training or environmental controls. I've already been exposed to enough hazardous materials in aerospace, I surely don't need to add to that Be into my lungs.
The real question is what were you testing for with the solder joint tester. Oxides on the surface will not impede the flow of transport current within the ribbon, nor will it alter the inductance vs frequency characteristics of the ribbon.
If on the other hand, you were to slit the ribbon into lots of individual ones that do not touch each other, that would break off eddy currents, and would show up in a frequency scan. High temperature superconductors have this very real problem, as the eddy currents totally kill the transfer efficiency at 60 hz, making the transport of 60 hz power lossy.
jn
Remember, we're not discussing how a difference in inductive reactance can be audible. We are discussing where the energy goes when the inductance abruptly changes.
If the inductance is changing while the conductor is carrying currents, the Q is, can it affect the end terminal voltage.
Don't forget, the terminal voltage of a system is:
V = L dI/dt + I dL/dt
We are discussing the I dL/dt component.
jn
That's been tested for, I have seen no evidence of interstrand "rectification" in any controlled test. You would have to contrive an extreme situation for there to be anything but minute interstrand potentials.
Only if you think in terms of physical contacts, perhaps. Such as relay contacts and oxides on the contact surfaces which can be mechanically broken thru.
If there is an N (copper) and a P (oxide) then an N (copper) again there is a continuous voltage drop across the copper/oxide/copper path. That oxide level break-thru voltage could be a potential issue over time. Keeping an open mind about it.
When you consider a new copper penny coin's color and the change in color after only a few days.... we are all listening to heavily oxidated copper wires. Historically, the High-End solution is to not try to measure it so much as to just eliminate it... enter OFHC. If it is a potential problem, then it is removed.... if it wasnt, no harm in having the OFHC seems to be a prevailing approach to many issues.
THx-RNMarsh
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