Re: [time-nuts] temperature sensor
What I am missing in all these discussions is what do we want to archive
or is this an other paper only discussion. I am used to starting out with a
goal, and tackle the challenge from there.
We have a saying in German "Papier ist geduldig. Translate You can write
any thing on paper.
Bert Kehren
In a message dated 7/20/2014 12:39:24 P.M. Eastern Daylight Time,
attila@kinali.ch writes:
Moin,
On Sun, 20 Jul 2014 07:55:23 -0700
"Tom Van Baak" tvb@LeapSecond.com wrote:
Thanks for this level of detail. Fascinating. Is the fundamental physics
behind the quartz angle-of-cut well understood, or does this fall into
advanced alchemy and industrial magic?
From what i gathered from my excursion into solid state phyiscs, the
properties of crystals can be calculated "easily". If i'm not mistaken
the SC cut was calculated before it was experimentally proven (sorry,
cannot find the reference for that).
There are also several software packages to simulate quartz crystals.
(e.g. CS-01 from maxis-01)
I understand about the time constant now. Yes, on the order of a
few seconds makes sense. Would it be possible to have other mounting
techniques that improve environmental contact with the crystal?
The problem here is, that any closer contact will lead to damping
of the crystal. Probably the best solution is, as Bob Camp said,
to use SAW instead of BAW.
Do you know of any commercial quartz crystals (say, in the $1 to $10
range)
that have been optimized for large tempco at room temperature? Or
optimized
for linearity over a large range (e.g., -40 to +40 C)?
As Bernd Neubig mentioned, Axtal has some:
http://www.axtal.com/English/Products/PiezoSensors/TemperatureSensors/
As none of the usual distributors carries them, i have no idea what
the price is. Maybe Bernd can answer that question.
I'm pretty sure other quartz manufacturers have some as well.
I was able to test
one once, a 5x7mm XO, but I don't know any more about it other than it
came
from Switzerland.
Hmm... The only quartz manufacturer in Switzerland that is still producing
anything, is AFAIK Microcrystal. I'm not aware of any other (after
Oscilloquartz got bought and their quartz business integrated into
Microcrystal).
Unless you got it over Quarz AG (www.quarz.ch) which is merly a
distributor.
(Yes, they sell beauty products too... )
BTW: for some reason, i did not get the two mails from Andras Pummer
which you quoted at the end of your mail. They don't seem to be in
the archives either.
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
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
What I am missing in all these discussions is what do we want to archive
or is this an other paper only discussion. I am used to starting out with a
goal, and tackle the challenge from there.
We have a saying in German "Papier ist geduldig. Translate You can write
any thing on paper.
Bert Kehren
Hi Bert,
Let me answer in two parts.
- The issue of precision temperature sensing is so key to the field of precise time & frequency that any thread that attracts more information, anecdotes, and wisdom from the group is very welcome. Quartz is such an amazing substance that its use as a precision sensor is every bit as interesting as its use as a precision timekeeper.
Not everything has to be goal oriented. Some discussions on this list are pure enjoyment, others highly educational, and some simply plant seeds. Starting with concrete goals is good for a business but when working with precision timing as a hobby, as most of us are, goals are sometimes secondary to just learning or playing around.
- If you want an example of a specific goal related to temperature, try this:
There have been several discussions over the years about variable fan speed based temperature control. I can't explain it, but I've always been suspicious of this technique. It seems to me still air is inherently better than moving air. Passive (no fan) is better than active (fan). And constant velocity is better than turbulence is better than variable velocity. But I don't know for sure. That's where experiments and measurement come in.
To satisfy my curiosity and get actual data I'd like to place 6 or more tiny analog high-resolution temperature sensors all around the OCXO of a Trimble Thunderbolt. That's high-resolution both in temperature and in time. In other words, no fake accuracy "averaging" allowed. The goal is to observe thermal gradients in real-time and see how good, or how bad, the correlation is among crystal temperature, case temperature, and DS1620 temperature sensor (which is mounted a considerable distance from the OCXO). The same technique, and maybe even the same conclusions, might apply to Rb.
/tvb
On Sun, 20 Jul 2014 23:18:38 -0700
"Tom Van Baak" tvb@LeapSecond.com wrote:
To satisfy my curiosity and get actual data I'd like to place 6 or more
tiny analog high-resolution temperature sensors all around the OCXO of a
Trimble Thunderbolt. That's high-resolution both in temperature and in time.
In other words, no fake accuracy "averaging" allowed. The goal is to observe
thermal gradients in real-time and see how good, or how bad, the correlation
is among crystal temperature, case temperature, and DS1620 temperature
sensor (which is mounted a considerable distance from the OCXO). The same
technique, and maybe even the same conclusions, might apply to Rb.
May i ask what speaks about using PT100/PT1000 or NTCs?
NTCs are dirt cheap, but might need some calibration first, to
get to time-nuts standards. But PT100 aren't that much more expensive
either.
eg:
The NTCALUG03 by Vishay don't look too bad, or if you want PT100
the M310 by Heraeus. The KN1510 by Heraeus look also nice, but are
a tad bit more expensive (about 20USD/pcs)
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
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
73
Alex
On 7/21/2014 1:22 AM, Attila Kinali wrote:
On Sun, 20 Jul 2014 23:18:38 -0700
"Tom Van Baak" tvb@LeapSecond.com wrote:
To satisfy my curiosity and get actual data I'd like to place 6 or more
tiny analog high-resolution temperature sensors all around the OCXO of a
Trimble Thunderbolt. That's high-resolution both in temperature and in time.
In other words, no fake accuracy "averaging" allowed. The goal is to observe
thermal gradients in real-time and see how good, or how bad, the correlation
is among crystal temperature, case temperature, and DS1620 temperature
sensor (which is mounted a considerable distance from the OCXO). The same
technique, and maybe even the same conclusions, might apply to Rb.
May i ask what speaks about using PT100/PT1000 or NTCs?
NTCs are dirt cheap, but might need some calibration first, to
get to time-nuts standards. But PT100 aren't that much more expensive
either.
eg:
The NTCALUG03 by Vishay don't look too bad, or if you want PT100
the M310 by Heraeus. The KN1510 by Heraeus look also nice, but are
a tad bit more expensive (about 20USD/pcs)
Attila Kinali
On Mon, 21 Jul 2014 04:39:51 -0700
Alexander Pummer alexpcs@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
Hello,
There are two types of NTC thermistors that are (very) frequently used
in spacecrafts, the Measurement Specialties (traditionally YSI, Yellow
Spring Instruments) 44907 and 44908, that are 10k @ 25ºC NTC:
http://meas-spec.com/downloads/44908.pdf and
http://meas-spec.com/downloads/44907.pdf
Both are specified in error against temperature, being ±0.1ºC for the
44908 and ±0.2ºC for the 44907, in the 0-70ºC range.
I suppose that these ones are obscenely expensive, but the "civilian"
versions are the 44006RC and 44031RC, with the same specified
tolerances, and the same calibration curve, and readily available (e.g.
from Farnell). I suspect that the difference between the space qualified
ones and the others are quality control and traceability, and perhaps
(only perhaps) a different low-outgassing epoxy coating, but probably
the sensor material is the same in all of them. The advantage is that
you get a quite good intial tolerance, so calibration can be simplified,
since you only need to calibrate the resistance measurement device with
known resistances to obtain a ±0.1ºC error from the sensors.
The qualification mandated by NASA for these sensors refers mainly to
MIL-PRF-23648 standard, that describes a load life test, consisting in
application of maximum power specified for the themsitor during 1000h,
intermittently (30min. on, 30min. off) and checking at 250, 500, 750 and
1000h that the thermistor remains in the specified tolerance in the
applicable specification sheet, so I suppose that these thermistors are
quite good wrt long-term stability.
In applications where more stability is required, also Pt thermistors
are used in spacecrafts (mainly Pt1000 and Pt2000, also others), but the
problem is that depending on the wire run, they shall be measured using
4-wire techniques, and also initial calibration is not so tight (when it
is so tight, they tend to be also very expensive) and not so easy (a
Pt1000 has a rough variation of 3ohm per ºC).
Regards,
Javier
On 21/07/2014 16:12, Attila Kinali wrote:
On Mon, 21 Jul 2014 04:39:51 -0700
Alexander Pummer alexpcs@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
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@kinali.ch wrote:
On Mon, 21 Jul 2014 04:39:51 -0700
Alexander Pummer alexpcs@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
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
I got a few of these
http://www.adafruit.com/products/374
to replace my TMP36. The idea was to get rid of the noise by using a
sensor with a built-in digital interface. They are spec'd for only 0.5C
accuracy but I think they are more repeatable and do much better than 0.5c
for relative measurements. You can use the link above to buy them but you
can also get free samples. Another advantage of the digital ones is you
can install several into the heat sink and all of them only take one pin so
you can add any number of these and still use the tiny 8-pin uP.
Calibrate any sensor with boiling water. Either just assume it is 100C or
look up the local air pressure and compute the boiling point.
Or, I just happened to have a good laboratory glass thermometer, the kind
that is about two feet long. Place it and the sensor in the same liquid
bath and cal is "close enough" for anyone who is not a "temperature nut".
I have not yet had time to use these in a real application. but it looks
like they work. Again you have to couple them well to whatever you are
measuring. Do not conduct the "wrong" heat into any of these devices via
the lead wires.
On Mon, Jul 21, 2014 at 9:02 AM, Javier Herrero jherrero@hvsistemas.es
wrote:
Hello,
There are two types of NTC thermistors that are (very) frequently used in
spacecrafts, the Measurement Specialties (traditionally YSI, Yellow Spring
Instruments) 44907 and 44908, that are 10k @ 25ºC NTC:
http://meas-spec.com/downloads/44908.pdf and http://meas-spec.com/
downloads/44907.pdf
Both are specified in error against temperature, being ±0.1ºC for the
44908 and ±0.2ºC for the 44907, in the 0-70ºC range.
I suppose that these ones are obscenely expensive, but the "civilian"
versions are the 44006RC and 44031RC, with the same specified tolerances,
and the same calibration curve, and readily available (e.g. from Farnell).
I suspect that the difference between the space qualified ones and the
others are quality control and traceability, and perhaps (only perhaps) a
different low-outgassing epoxy coating, but probably the sensor material is
the same in all of them. The advantage is that you get a quite good intial
tolerance, so calibration can be simplified, since you only need to
calibrate the resistance measurement device with known resistances to
obtain a ±0.1ºC error from the sensors.
The qualification mandated by NASA for these sensors refers mainly to
MIL-PRF-23648 standard, that describes a load life test, consisting in
application of maximum power specified for the themsitor during 1000h,
intermittently (30min. on, 30min. off) and checking at 250, 500, 750 and
1000h that the thermistor remains in the specified tolerance in the
applicable specification sheet, so I suppose that these thermistors are
quite good wrt long-term stability.
In applications where more stability is required, also Pt thermistors are
used in spacecrafts (mainly Pt1000 and Pt2000, also others), but the
problem is that depending on the wire run, they shall be measured using
4-wire techniques, and also initial calibration is not so tight (when it is
so tight, they tend to be also very expensive) and not so easy (a Pt1000
has a rough variation of 3ohm per ºC).
Regards,
Javier
On 21/07/2014 16:12, Attila Kinali wrote:
On Mon, 21 Jul 2014 04:39:51 -0700
Alexander Pummer alexpcs@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
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/time-nuts
and follow the instructions there.
--
Chris Albertson
Redondo Beach, California
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@gmail.com
To: "Discussion of precise time and frequency measurement"
time-nuts@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@kinali.ch wrote:
On Mon, 21 Jul 2014 04:39:51 -0700
Alexander Pummer alexpcs@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
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Hi:
The temperature of steam can be anything above boiling water.
http://en.wikipedia.org/wiki/Steam
Super heating of steam was common railroad practice.
Boiling pure water will get rid of any trapped gases quickly.
In fact this is the recommended thing to do to tap water before using it for freshly cut roses.
Of course you need to let the water cool before putting them into it. Removing the trapped oxygen makes them last longer.
Have Fun,
Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
http://www.prc68.com/I/DietNutrition.html
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@gmail.com
To: "Discussion of precise time and frequency measurement" time-nuts@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@kinali.ch wrote:
On Mon, 21 Jul 2014 04:39:51 -0700
Alexander Pummer alexpcs@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
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.