The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
Date: Thu, 14 Nov 2002 20:06:04 -0500
From: "Raymond E. Rogers"
X-Mailer: Mozilla 4.76 [en] (Win95; U)
Subject: Re: Temperature Measurement Stability
References: <3DD2EC20.2FB10158@maine.rr.com> <email@example.com>
X-Comments: This message was posted through Newsfeeds.com
X-Comments2: IMPORTANT: Newsfeeds.com does not condone, nor support, spam or any illegal or copyrighted postings.
X-Comments3: IMPORTANT: Under NO circumstances will postings containing illegal or copyrighted material through this service be tolerated!!
X-Report: Please report illegal or inappropriate use to
X-Abuse-Info: Please be sure to forward a copy of ALL headers, INCLUDING the body (DO NOT SEND ATTACHMENTS)
Organization: Newsfeeds.com http://www.newsfeeds.com 80,000+ UNCENSORED Newsgroups.
Thanks Bill, comments embedded
Bill Sloman wrote:
> RS Components stock DIN B/3 parts, which is to say +/-0.1C
> Hart Scientitic will sell you a calibrated Pt100 four wire sensor assembly
> good to +/-0.02C for a hundred dollars or so, and the electronics to read it
> to that accuracy for about $1500. We use a Thurlby-Thandar 1906 computing
> multimeter as a four-wire ohmeter, and convert the resistances to
> temperature by solving the quadratic in Excel - not quite as good, but much
We bought a $4000 NIST traceable thermsitor Thermometer that I am going
to use for calibration. I have several other thermal problems and
wanted something reliable (if ungainly).
> For a more comprehensive discussion of temperature stabilisation near room
> temperature, see A W Sloman, Paul Buggs, James Molloy and Douglas Stewart "A
> microcontroller-based driver to stabilize the temperature of an optical
> stage to within 1mK inthe range 0-38C, using a Peltier heat pump and a
> thermistor sensor" published in Measurement Science and Technology volume
> 7,. pages 1653-64 (1996), which is not only useful in its own right (if I
> say so myself) but cites about a dozen earlier papers with useful content.
> The +/-0.2C Betatherm thermistors we used are claimed to drift less than
> 11mK per year at 75C. Yellow Springs Instruments offers some +/-0.05C
> tolerance parts that ought to be even more stable, and are available off the
> shelf from Newark - they have 16 of the 10k at 25C part 46006 (stock no
> 46F3197) for $47.60 each.
Yes we bought some from YSI that in fact have data to back up the
stability claims; and they are costing about $100. Okay for research
but probably to much for production.
> A couple of the papers we cited achieved much better than millidegree
> stability. Larsen's classic paper describes a 50 microdegree stability water
> bath built around a 500R platinum resistance sensor, and Priel got down to
> +/-3.5 microdegrees with a Fenwall thermistor sensor. Preil complained that
> dissipating more than 16uW in his sensor produced appreciable long term
> drift, but probably within the +/0.03C range asked for by the original
> Interchangeable thermistors from reputable suppliers should be pretty
> stable. Their great advantage is their high sensitivity - about -4% per
I will make a calibration fixture. We can spend money on capitol
equipment but the shipped instrument must be cheap (relatively
speaking). I gave up on interchangability.
> degree C, compared with +0.39% for Pt100 and Pt1000 sensors. This not only
> makes the job of the measuring electronics much easier, but lets you get
> away with cheaper and more easily accessible current-setting resistors and
> so forth. A DIN B/3 Pt100 is a +/-0.04% resistor, and using anything less
> than $10 Vishay 0.01% resistor throws away most of the accuracy you've paid
> for. The YSI +/-0.05C thermistors are +/-0.2% resistors ...
> The National Semiconductor LM35 semiconductor temperature sensor is a bit
> noiser than a good thermistor or a platinum resistance sensor, but even
> easier to use. My office mate at Nijmegen University used the metal-packaged
> part for some millidegree stability temperature calibration baths and was
I found the national data sheets .1 - .2 degC/khr , not good enough.
> very happy with their long term stability. The Dallas parts may be suspect -
> we had a posting here a couple of years ago about some nasty temperature
> drifts that turned out to be humidity driven. Water vapour was getting
> through the plastic packaging. I'm sure that the problem has been solved by
> now, at least at the level of performance guaranteed on the data sheet.
I have yet to find the Dallas drift specs. I will try to look up your
paper and follow the references.
Maybe I can use your paper as an authoritative reference instead of the
-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 80,000 Newsgroups - 16 Different Servers! =-----
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup