[time-nuts] temperature sensor

Alex Pummer alex at pcscons.com
Mon Jul 21 22:56:27 UTC 2014



the broiling temperature is dependent of the atmospheric pressure! the 
water broils at 100C° only a see level!

73
Alex


On 7/21/2014 11:56 AM, Alan Melia wrote:
> 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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