That is very unclear from the diagram. My interpretation is that PTFE's piezoelectricity is relatively low, but that the author did not break out specific materials for the triboelectric portion, presumably because it's a function of pairs of materials.
The following three - DF96, marce and SY - should order enough popcorn
Quite funny to follow this threesomes postings...
Personally I beg to differ.
I tend to read their posts because they give food for thought and I tend to learn something useful from many of them.
Yours I read for the entertainment value. No more, no less.
Now where is that damn popcorn?
I hear any tapping, sliding, vibration...
I had a problem with a mike cable being very microphonic in the production area. Over the years the rebar embedded in the concrete floor became magnetized, as years ago nobody cared about the stray fields in 5 and 6 tesla magnets. CRT's will change color depending on where they are, and how they are rotated.
Turns out when the cable hit the floor over rebar, the sound amplified through the system.
I suspect that there is some component of induction that occurs as a result of mechanical vibration of the twisted pair in the earth's magnetic field, half gauss.
The following three - DF96, marce and SY - should order enough popcorn
Quite funny to follow this threesomes postings...
Yes, it certainly is. I enjoy reading them.
They are correct of course, but still enjoyable.
You have stated as factual, many things which are actually conjecture or repeated fiction of others, and provide no evidence.
jn
Low electrical noise due to mechanical movement or stress.
Can't speak for Belden or Canre, but Mogami uses a layer of conductive plastic between the shield and the polyethylene that insulates the center conductor.
se
Under the strictest conditions (we were guaranteeing 20fA input current) boards assembled with virgin teflon standoffs, Victoreen glass resistors (1000G Ohm), and FR4 (mistake) freshly cleaned in a freon bath took 24hrs. to make stable readings. I mean stable readings, ~100's of electons per second. This seemed to be totally due to surface charge on the FR4 that had to bleed away even though no components touched it except via teflon.
I suspect it would have taken less time if I waved my piece of pitchblende over it.
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That's pretty damn fancy.
Wonder if it would have any particular advantage over a layer of carbon-loaded PVC.
se
Those electrons need to get themselves unionized then into an organized work force.
No salt on mine please, just toffee
I like mine mixed half salted, half sugared.
The Keithley book:
Low Level Measurements Handbook:
Precision DC Current, Voltage, and Resistance Measurements (6th edition: 2004)
Welcome to Keithley?s Knowledge Center - Keithley Instruments Inc.
http://www.keithley.com/knowledgecenter/knowledgecenter_pdf/LowLevMsHandbk_1.pdf
Low Level Measurements Handbook:
Precision DC Current, Voltage, and Resistance Measurements (6th edition: 2004)
Welcome to Keithley?s Knowledge Center - Keithley Instruments Inc.
http://www.keithley.com/knowledgecenter/knowledgecenter_pdf/LowLevMsHandbk_1.pdf
Yesterday I spent some time trying to replicate Mr. Simon's conductive "dead zones" with no luck. I tried the worst connections I could make like single twists of 40yr. old uncleaned resistor leads, etc. and only got a connection or no connection. To remind folks it was postulated that there could be poor connections that only needed mV's to "jump" even though there is no physics to explain the phenomena (see Paschen's law). I will also mention that the semiconductor industry depends on relatively tiny tungsten to aluminum contact probes to test microvolt offsets and picoamp currents by the 10's of millions a day. My personal experience is that <5uV contact potential repeatability can be maintained easily. The probes use only pressure and pushing through the few microns of aluminum is a no-no.
Ed I'm sure I got this all wrong, so please make any suggestions. I am using the test enclosure from an old Keithley electrometer and a battery powered 1.4nV gain of 40db box that I built. I can easily see the voltage from the contact resistance and there actually is a tiny third harmonic tone above the noise (-130dB or so) but the waveform of the contact voltage is a nearly perfect sine wave in each case. After my gain box I have a standard USB mic preamp with up to 60dB more gain, the RTI noise floor is almost 30dB above the sound card and save for some line incursion there are no tones to explain away. I can amplify the contact potential from 10's - 100's of uV to full scale.
Ed I'm sure I got this all wrong, so please make any suggestions. I am using the test enclosure from an old Keithley electrometer and a battery powered 1.4nV gain of 40db box that I built. I can easily see the voltage from the contact resistance and there actually is a tiny third harmonic tone above the noise (-130dB or so) but the waveform of the contact voltage is a nearly perfect sine wave in each case. After my gain box I have a standard USB mic preamp with up to 60dB more gain, the RTI noise floor is almost 30dB above the sound card and save for some line incursion there are no tones to explain away. I can amplify the contact potential from 10's - 100's of uV to full scale.
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Scott,
There ain't no microdiodes for the umpteenth time.
If you want to see contact failure, you get a single shot at it. You use a slow sweep from 0 volts to say 2000 mV, looking at the current you will see it jump as the sulphates in the contact clear.
Once cleared the contact will work for a bit until the sulphate film rebuilds.
Just about anyone who has used cheap microphone systems will be glad to tell you about the time the mic didn't work until they tapped on the microphone.
Now the other question is when you see third harmonic distortion does the ratio of it change with absolute level. I.E. is it the same at 1 mV as 1 Volt?
ES
There ain't no microdiodes for the umpteenth time.
If you want to see contact failure, you get a single shot at it. You use a slow sweep from 0 volts to say 2000 mV, looking at the current you will see it jump as the sulphates in the contact clear.
Once cleared the contact will work for a bit until the sulphate film rebuilds.
Just about anyone who has used cheap microphone systems will be glad to tell you about the time the mic didn't work until they tapped on the microphone.
Now the other question is when you see third harmonic distortion does the ratio of it change with absolute level. I.E. is it the same at 1 mV as 1 Volt?
ES
Nope don't see it, no contact is no contact up to volts. You showed sine waves with small flat spots at zero and I remember the mention of 10's of mV. What on earth is surprising about a bad connection that you have to jiggle to get it to work once and a while. I have expensive Tek probes that have that problem. Once you maintain metal to metal I would ask SY if any oxidation could break the connection or more likely use has broken it and it is back on another spot you need to break through mechanically.
I guess the resistor stuff might be more interesting, or maybe the chain of solder joints (I forgot what that did).
I guess the resistor stuff might be more interesting, or maybe the chain of solder joints (I forgot what that did).
Don't worry if you don't see. lots of others have experienced it.
I still have my missing zero test piece. Haven't yet found another that shows up as clearly. But although I can see some interesting stuff, there are not a lot of examples. After I concluded that the issue was sulfur contamination rather than O2, there was not much more I was learning, so the gizmos went on the shelf. Now when somebody wins a prize by taking it one step farther and discovering it was all due to misaligned gravitrons, I'll feel foolish.
Now in the 60's when resistor distortion first became an issue one of the considerations was that each individual resistor varied from another by a significant amount. That is why they used the particular third order harmonic test.
My test uses reciprocity and requires to faster convergence resistors that are very similar.
As you are testing old carbon comp resistors, you may wish to stick with a bridge of three known superior resistors and a single unit under test. As you are aware power dissipation is an issue. So I would suggest low frequencies and low voltage with lots of averaging.
BTY I think i made my position clear in posts 105 & 533.
ES
I still have my missing zero test piece. Haven't yet found another that shows up as clearly. But although I can see some interesting stuff, there are not a lot of examples. After I concluded that the issue was sulfur contamination rather than O2, there was not much more I was learning, so the gizmos went on the shelf. Now when somebody wins a prize by taking it one step farther and discovering it was all due to misaligned gravitrons, I'll feel foolish.
Now in the 60's when resistor distortion first became an issue one of the considerations was that each individual resistor varied from another by a significant amount. That is why they used the particular third order harmonic test.
My test uses reciprocity and requires to faster convergence resistors that are very similar.
As you are testing old carbon comp resistors, you may wish to stick with a bridge of three known superior resistors and a single unit under test. As you are aware power dissipation is an issue. So I would suggest low frequencies and low voltage with lots of averaging.
BTY I think i made my position clear in posts 105 & 533.
ES
I tested chains of 200 or so joints done with different solders. The final results were that I did not have any bad solder joints, the lead free solders are not as shiny and produce smaller fillets. As to distortion with 200 joints if there was any distortion difference it was at the limits of the testing.
There was however significant difference in re-soldering the connections on a PC test card. As soon as the through plated holes were filled with 63/37 solder the entire circuits distortion dropped by an easily measured result.
But that changes the resistance dramatically. I easily measure the effects of that on boards all the time it has nothing to do with the solder per se. I see the light now, measurements without analysis or elimination of confounders, I won't waste anymore time.
BTW a half bridge driven 180 degrees out of phase allows a direct comparison with only one reference component. So there was a flat spot component?
EDIT - Ah yes #105, directional cable distortion I should have started there. Back to the drawing boards? Then again others will still have heard it and the time still wasted.
BTW a half bridge driven 180 degrees out of phase allows a direct comparison with only one reference component. So there was a flat spot component?
EDIT - Ah yes #105, directional cable distortion I should have started there. Back to the drawing boards? Then again others will still have heard it and the time still wasted.
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Yes beliefs may be based on observation of magic in action. Once you peek behind the veil, it ain't very mysterious.
Yes a half bridge gets you back to the 60's methods.
Yes I have a very flat spot DUT and a few just above the noise level maybes, out of a few hundred samples of low quality DUTs.
If you have an RF network analyzer you might just find as others have that RF cables are directional! (SWR) I find consistent, repeatable and have demonstrated differences in distortion in audio interconnect cables depending on which way they are plugged into my gear. You are welcome to try this yourself. If you want references! PM me.
ES
Yes a half bridge gets you back to the 60's methods.
Yes I have a very flat spot DUT and a few just above the noise level maybes, out of a few hundred samples of low quality DUTs.
If you have an RF network analyzer you might just find as others have that RF cables are directional! (SWR) I find consistent, repeatable and have demonstrated differences in distortion in audio interconnect cables depending on which way they are plugged into my gear. You are welcome to try this yourself. If you want references! PM me.
ES
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