[time-nuts] OT, looking for a good science forum

[Jim Lux]

On 1/26/13 11:23 PM, Chris Albertson wrote:
> On Sat, Jan 26, 2013 at 2:12 PM, J. Forster <jfor at 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
>