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Topic: Need to measure -30c to 150c (Read 808 times) previous topic - next topic

Larry E

Hello Forum, I am in need of some help with measuring very low temperatures.  The LM35 sensor has the range, but from +25c to -55c the output is in negative volts.  How do I deal with this problem.    Thanks for any help, Larry


Bias the output so the whole range is positive.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

Larry E

How would that be done?  Larry


Use a TMP36 aka LM50. It does not require a negative supply voltage


A type T or J thermocouple would work, too.

The current requirement is pretty small, 50 uA, so a battery would last a long time.

You could use an Op-Amp to level shift the voltage.


How would that be done?  Larry

Erm use the example in the datasheet? Figure 18. http://www.ti.com/lit/ds/symlink/lm35.pdf

The DS18B20 only does -55 to 125C alas.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]


Use TMP 01 and get the temerature i degrees Kelvin. Zero is realy zero.


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