[time-nuts] temperature sensor

Alan Melia alan.melia at btinternet.com
Mon Jul 21 14:56:24 EDT 2014


er not boiling water....steam. Water's boiling point is affected by the 
dissolved gasses and other contaminants.

Alan
G3NYK
----- Original Message ----- 
From: "Bill Dailey" <docdailey at gmail.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Monday, July 21, 2014 5:43 PM
Subject: Re: [time-nuts] temperature sensor


> Ice water and boiling water coupled with altitude will give you two 
> points.
>
> Sent from mobile
>
>> On Jul 21, 2014, at 10:12 AM, Attila Kinali <attila at kinali.ch> wrote:
>>
>> 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
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