If one does a ratiometric measurement comparing the voltage drop across the RTD with the voltage drop across a stable low Tc resistor connected in series with the RTD the excitation source only needs to be quiet with good short term stability.
Bruce > On 29 September 2020 at 07:48 "John Moran, Scawby Design" > <j...@scawbydesign.co.uk> wrote: > > > Thanks for going easy on me Bob ... a case of more haste, less speed! I > focussed on low long-term drift specs without realising I had turned up a > voltage reference, sorry. > > However, I have found some YSI glass encased thermistors that have long-term > drift specs of <10mK at 25C and 75C over a period of 100 months. They are in > the YSI 46000 series - data sheet attached. > > http://www.farnell.com/datasheets/169207.pdf > > There is an interesting paper by NIST on achieving the International > Temperature scale - link attached (it is 196 pages and 10MB) that seems to > indicate platinum sensors are the most stable at less than 1mK and, of > course, to be able to measure these resistors accurately, you need an equally > low-drift voltage/current source. :-) > > https://nvlpubs.nist.gov/nistpubs/Legacy/TN/nbstechnicalnote1265.pdf > > This reference appeared from an EEVblog where I think some Volt-nuts were > discussing temperature. One of them confirmed that the most economical way > was to have a group of lower-cost sensors and characterise them. > > https://www.eevblog.com/forum/metrology/long-term-stability-of-temperature-sensors/ > > John > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
