Hi!

Could those who work with temperature logging equipment please help.

I have just completed a PIC based temperature data logger using a NTC
thermistor as a sensor.  A PC interface program contains a regression
routine to correct for the non-linear response of the NTC thermistor. I am
aiming to calibrate the device for better than +/- 0.02 C.  The zero point
should be no problem.  Has anyone experience with variations from 0 C due to
differences in purified water quality  (e.g. standard deionised, distilled
or ultrapure)?

The device is only required to measure temperatures between 0 and 50 C.  At
100 C, there are too few TMR0 derived counts to use this temperature for
calibration and I think it risky to depend on the accuracy of a
mercury-in-glass thermometer.  Does anyone know of a high scale temperature
reference around 50 +/- 0.02 C?