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Old 5th September 2012, 08:19 PM   #741
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Originally Posted by Wavebourn View Post
Today with availability of semiconductor coolers temperature can be kept below minimal ambient temperature level, but it creates moisture problem.
Wait a minute. What is with you?
First heating above ambient temperature, now cooling below ambient temperature.

I think I’ll have some pills. (Do you know the waveform of the “positive vibrations”?)

I know about the good name of the Tomsk Polytechnic Institute, but I was not aware of this exciter.

George
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Old 5th September 2012, 08:28 PM   #742
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Polytechnic institute is an educational one. NIIPP is a scientific one.

Here is their modern online store. Google Translate

Looks like Russian electronic industry went down to China...
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Old 5th September 2012, 08:29 PM   #743
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I discovered the hard way that aluminum wire to gold plated Kovar has a residual 2-3uV/C thermocouple potential.
Scott, have you looked on such potentials from copper to solder to copper or copper/gold plating to solder to copper ? (moving coil cartridges and microphones circuits)

George
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Old 5th September 2012, 08:29 PM   #744
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I think I’ll have some pills.
George
The question is....the red one, or the blue one...

jn
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Old 5th September 2012, 08:35 PM   #745
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Scott, have you looked on such potentials from copper to solder to copper or copper/gold plating to solder to copper ? (moving coil cartridges and microphones circuits)

George
No such research is a lot of work and I asked one of the foremost experts in the field and he told me he knew of very little (none?) literature on thermocouples with thin different metal films.

I actually made little knots of gold and aluminum 1 mil wire by hand.
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Old 5th September 2012, 08:42 PM   #746
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Originally Posted by bcarso View Post
77 K is far too cold for good performance with silicon JFETs.
May I ask why?
Is this true for bipolars too?
(Lack of basic knowledge. I thought I knew that lowering temperature lowers every kind of semiconductor noise )

George
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Old 5th September 2012, 08:49 PM   #747
gpapag is offline gpapag  Greece
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Originally Posted by jneutron View Post
The question is....the red one, or the blue one...

jn

Ooops !

The only blue pill that comes to my mind is Viagra
What about the red one ?

George
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Old 5th September 2012, 08:52 PM   #748
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Ooops !

The only blue pill that comes to my mind is Viagra
What about the red one ?

George
Matrix....

jn
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Old 5th September 2012, 08:53 PM   #749
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May I ask why?
Is this true for bipolars too?
(Lack of basic knowledge. I thought I knew that lowering temperature lowers every kind of semiconductor noise )

George
Obscure, here you go germanium JFET's at 4.2K.

http://ntrs.nasa.gov/archive/nasa/ca...2000033912.pdf
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Old 5th September 2012, 08:56 PM   #750
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May I ask why?
Is this true for bipolars too?
(Lack of basic knowledge. I thought I knew that lowering temperature lowers every kind of semiconductor noise )

George
I think it's because the electrons didn't bring any thermal underwear, so when they get to the wall, they are not able to climb over it..but shiver instead..

At really low temps, the pn junctions actually become insulating to the tune of 3 to 30 volts depending on diffusion profile.

jn
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