[time-nuts] poor-man's oven
jimlux at earthlink.net
Mon Jun 5 08:29:39 EDT 2017
On 6/4/17 10:01 PM, Chris Albertson wrote:
> Voltage is proportional to the product of resistance and absolute
> temperature. As an experiment place a voltage across a high value
> resister like say one 1M raise the volts until you are near the limit of
> the resister and connect it via a coupler cadaster to an audio amplifier.
> You will hear white noise in the speakers.
As in Johnson noise - vrms = sqrt(4kTR)
> There is a similar effect in semi conductors. The best example of this is
> visual noise in digital camera, when you tern the gain way up (set the ISO
> high) you can see it in the photo.
I believe that's a different mechanism, shot noise.
> All of this is proportion; to absolute.
> As I remember we ran the "oven" at -20C There was a valve used to flash out
> the air inside with inert welding gas to reduce ice.
> Some people use vacuum and get to cryogenic temperatures. But that is
> expensive and way-hard without an institutional size budget.
cryogenic (as in LN2 temps) is very hard with TEC it takes many stacked
devices that wind up looking like a ziggurat.
near vacuum isn't that tough at home - refrigeration vacuum pumps are
inexpensive. If it's a one time thing, a sorption pump and one time Ln2
or Dry Ice can get you pretty empty as a one shot. Then you seal it off
and it's done.
the Bell Jar - http://www.belljar.net/ is a handy reference of vacuum
>> What is the reason why you'd expect less noise with a TEC?
>> Attila Kinali
>> You know, the very powerful and the very stupid have one thing in common.
>> They don't alters their views to fit the facts, they alter the facts to
>> fit the views, which can be uncomfortable if you happen to be one of the
>> facts that needs altering. -- The Doctor
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