[time-nuts] temperature sensor

Attila Kinali attila at kinali.ch
Mon Jul 21 10:12:21 EDT 2014


On Mon, 21 Jul 2014 04:39:51 -0700
Alexander Pummer <alexpcs at ieee.org> wrote:

> NTC are not that very stable, they are amorphous material winch could 
> recrystallize slowly and therefore change it's electrical behavior , 
> PT100 style is more reliable since it is pure metal

How long is the time constant for NTCs?
I guess, it wouldn't matter for most of the measurements we do,
as NTCs need to be "calibrated" before precision measurements
anyways. Unless one measures over several months, or years.
But on this timescales, i wouldn't really trust an off the shelf
PT100 either. Not unless i measure its stability

For use in GPSDOs and OCXOs, i guess it doesn't really matter,
as long as the NTC stays within spec. There an external loop
corrects for the variation/drift of the measurement.


While we are at it: what is a good way to calibrate/characterize
temperature sensors that is available to hobbyists?

			Attila Kinali

-- 
I pity people who can't find laughter or at least some bit of amusement in
the little doings of the day. I believe I could find something ridiculous
even in the saddest moment, if necessary. It has nothing to do with being
superficial. It's a matter of joy in life.
			-- Sophie Scholl



More information about the time-nuts mailing list