On 1/26/13 11:23 PM, Chris Albertson wrote:
On Sat, Jan 26, 2013 at 2:12 PM, J. Forster <j...@quikus.com> wrote:
Unless you are doing fundamental physics research, are you sure you need a
cryo temperature standard?
You are right. What I asked I should have said that 1% accuracy would
be good enough. I'm pretty sure now that I can get to the 1% level
for well under $20. They sell small thin film platinum RTD for about
$8. They look like a tiny SMD resistor. I could place a constant
current across it and meaure the voltage drop.
You can get prewired RTDs from a variety of sources (they're used by
people building beer brewing setups, sous vide, etc. to hook up to a PID
controller).
Dry ice sublimation might be the safest calibration method and close
enough for thr 1% goal maybe. Another calibration point might be the
boiling point of water.
Ice and BP of water is probably all you need. Measure air pressure, of
course.
You could also buy one *good* thermometer to use as a secondary standard
to calibrate against.
I don't need to design this now, it was an example equestion
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