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Old 14th July 2011, 09:54 PM   #14041
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OK my gear for this measurement was bought new by me, but has never been recalibrated so there may be some error, but I am certain it is only a few percent.

The small diode measured .123 l x .064 d, the larger diode .203 x .104! (Inches!)
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Old 14th July 2011, 10:09 PM   #14042
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Could be mircorgaps! Whatever it is, it is.
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Old 14th July 2011, 10:45 PM   #14043
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Quote:
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Actually long ago I was in a group working on a semi-high power laser It ran at 22kv 200a around 3 pps. The trigger used a krytron for the first stage switch. I had not only never seen one before, but had never heard of one. Of course that was because they were I think still classified as secret (Lower Level).

So yes during that project I also learned a bit about the breakdown of air. One fellow got his PHD photographing how punch through in air actually happened! Really neat pictures!

I am less worried about air gaps as I am oxide formations on the surfaces of what should be mechanically connected components. How do you make a variable resistor without a wiper and associated problems?
There are no metal oxide/metal junctions that change from conducting to not over a 1 or 2 milli-volt span. Fermi levels, activation energies, bandgaps, whatever they all often have those pesky exponential relationships with temperature as well as values in the volt range.
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Old 14th July 2011, 10:49 PM   #14044
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There are no metal oxide/metal junctions that change from conducting to not over a 1 or 2 milli-volt span. Fermi levels, activation energies, bandgaps, whatever they all often have those pesky exponential relationships with temperature as well as values in the volt range.
Ever see a guy tap a dead microphone to get it to work?
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Old 14th July 2011, 11:05 PM   #14045
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Ever see a guy tap a dead microphone to get it to work?
Your plot shows about 50mV per div, a typical microphone has 20mV at 94dB SPL so why is there no output? You grind a bad connection back together by working the two halves around, no need for any exotic explaination. Same thing with corroded batteries.
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Last edited by scott wurcer; 14th July 2011 at 11:09 PM.
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Old 14th July 2011, 11:54 PM   #14046
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I meant to say: microgaps. Sorry, still sort of blind.
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Old 15th July 2011, 01:23 AM   #14047
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All, please try to stay technical. All cheap shots will be deleted.
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Old 15th July 2011, 04:24 AM   #14048
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Thanks everyone for the insights into ferromagnetic case effects (my nickel plated aluminum cases' self respect appears to have returned as well).

-Antonio
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Old 15th July 2011, 05:38 AM   #14049
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Magnoman, going to the hi fi show? If you do, be sure to stop by Constellation Audio and look at the aluminum cases (with damping) that we are designing with. Mine weighs over 90lb, I am told. (Only rich guys need apply '-)
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Old 15th July 2011, 01:11 PM   #14050
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Originally Posted by simon7000 View Post
OK my gear for this measurement was bought new by me, but has never been recalibrated so there may be some error, but I am certain it is only a few percent.

The small diode measured .123 l x .064 d, the larger diode .203 x .104! (Inches!)
Several things confuse me.

1. Was your caliper calibrated? Digital or analog.
2. What was room temperature? Is the caliper TCE the same as the diode TCE? stainless is 166 ppm/C, silicon about 4, molybdenum 3.3, copper 16, aluminum 25..if ya gonna measure, do it right...
2. Why do you call a diode that is .123 inches by .064 diameter small??? A 1N4148 chip is .008 inches thick, and .012 by .012 inches..
3.. Why do you call .203 by .104 big?? The one on my desk is 3.5 inches wide and 8 inches long, weighs 11 lbs. ""you call that a knife??...now...that's a knife...""

Any schematic of the setup??

Cheers, John
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