Bruce Griffith points to the note put out by Littelfuse. It is very meagre. It says that '...thermistors can be produced with typical drift of only 0.001˚C to 0.002˚C per Year." It doesn't say that they are produced and still less that Littelfuse produces them. Bruce also refers to thermistors being 'Suitably conditioned at 25˚C' What is this conditioning process and what if the intended working temperature is not 25˚C?. Surely more must be known about this matter. Jeremy Nichols' questions are very apposite. I see that the Steinhart Hart Equation seems to be entirely empirical without any underlying semiconductor theoretical foundation. John Ponsonby
Do we know what this ?Long Term Aging Process? is or is it proprietary? On Sat, Sep 26, 2020 at 5:03 PM Bruce Griffiths <[email protected] <mailto:[email protected]>> wrote: > Drift ~1-2mK per year for suitably conditioned thermistors at 25C: > > > https://www.littelfuse.com/technical-resources/technical-centers/temperature-sensors/thermistor-info/thermistor-terminology/stability.aspx > > <https://www.littelfuse.com/technical-resources/technical-centers/temperature-sensors/thermistor-info/thermistor-terminology/stability.aspx> > > > > Bruce > >> On 27 September 2020 at 11:15 Bob kb8tq <[email protected] >> <mailto:[email protected]>> wrote: > >> > >> > >> Hi > >> > >> Roughly speaking 99.99999% of all OCXO?s use thermistors as temperature > sensors. > >> The normal evaluation process on a new one *probably* would catch > something < 0.01C > >> over a few months. You may do it a couple different ways depending on > the target > >> OCXO. The net result is still in the ?golly gee wiz low? sort of range. > If you can detect a > >> drift / shift, you disqualify that part and move on to another one. Very > few glass bead > >> parts seem to get tossed out ?.. > >> > >> Bob > >> > >> > >> > >>> On Sep 26, 2020, at 4:23 PM, John Ponsonby <[email protected] >>> <mailto:[email protected]>> > wrote: > >>> > >>> Have any time-nuts got any data on the long term stability or drift > rates/ageing characteristics of thermistors? I am concerned with ability > of holding temperature constant at the milliK level for years. I reckon > that if one can measure it one can control it. Conversely if one can't > measure it, because of the instability of the sensor, one can't control it. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
