Quote:
Originally Posted by AC_Hacker
I think that your selection process is really a good approach... but, be careful, you might become a scientist.
|
/grin
For the measurements on my HRV I am looking for resolution, plus 4 thermometers that agree with eachother, and I have 2 sets now.
I fully agree with you that 'digital' is by no means a guarantee for precision nor quality.
The 'known-good' thermometers I referred to in my OP are alcohol columns and they agree with the roomthermostat that came with my central heating furnace. These 2 were €1,95 each ($1.50) but they lack the resolution I want for my purpose.
Your suggestion to calibrate these elcheapos with melting ice is a good one that I thought about, but forgot to actually do. I opened one of the elcheapos to see if there was anything adjustable inside but there wasn't. Probably the sensor and the electronics are fine but there is no compensation for the wiring and the solderingcontacts.
There is a reason that high quality industrial PT100 sensors use a total of 4 wires to compensate in realtime for resistance issues and temperature differences, see:
PT100 on wikipedia
Fornax