Measuring temperature with B. Stamp2

Joe

Hi,

Only to know an other chip ( instead DS1620)
becasue I am using a Bs2 with a DS1620 but I need
to read lower temperatures.

I need to read temperatures about -130ºF (-90ºC).

Any help?

Thanks, Joe

LoopyByteloose

Well, I believe the DS in the DS1620 represents Dallas Semiconductor.

They may have another product. You can also search Digikey for available product and prices.
Obviously, you have a very special need.

Alternatively, you might consider using a thermocouple if there is an appropriate low temperature one. But as far as I know, they are made for extreme high temperatures. Google is your friend.

You may have exceeded the functional limit of semiconductor physics and need to find a way to acquire data secondarily.· Low level IR sensors come to mind.

Postscript·-- www.ysi.com has platinum wire sensors down to -200 decrees C, but you best have deep pockets.· They seem to have several technologies with other barriers at about -55·and·-80

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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

Post Edited (Kramer) : 11/17/2005 5:15:25 PM GMT

Joe

Thanks,

Do you know an other place to buy?.

Thanks, Joe

Forrest

Omega has a wide variety of thermocouples www.omega.com/toc_asp/sectionSC.asp?section=A&book=temperature

Joe

Many thanks,

I will study this.

Thanks, Joe

Philip Gamblin

Is there some other mechanism or parameter you could measere to achieve to get the data you want?

LoopyByteloose

I just love to explore the limits of technology. Cold seems to be a real frontier.

I was surprised to see that Omega has 100 ohm Platinum wire in glass for $51 and $45 USD. These are rated at -220 degrees to +400 degrees C. Of course, you still have to integrate that into a calibrated system, but the can actually be immersed [noparse][[/noparse]in what I don't know].

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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

metron9

You could use just any thermistor using a heating circuit.

You could use enough current to actually heat the thermistor while it is attached/imersed.

I am thinking using a thermistor that has more resistance the colder it gets you drive current through it as part of a resistor ladder. Measure the voltage across the first resistor using an ADC.

Using time as your measurement, it will take much longer to reduce the resistance in the thermistor when it is at -130 than when it is at -100, monitoring the voltage on the second resistor tells you when the resistance has hit your target and some math to calculate the time it took could give you your tempreture.

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Think outside the BOX!

Tracy Allen

Type E thermocouples (chromel constantan) are popular for cryogenic applications down to -270 celsius (a mere 3 degrees above absolute zero. They are the usual sensor in environmental chambers cooled by liquid Nitrogen or LCO2. Type K and type T general purpose couples are also useful down to the -200 degrees Celsius range.

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Tracy Allen
www.emesystems.com