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Author Topic: Need to measure -30c to 150c  (Read 439 times)
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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


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I don't think you connected the grounds, Dave.
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Bias the output so the whole range is positive.
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How would that be done?  Larry
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Use a TMP36 aka LM50. It does not require a negative supply voltage
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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.
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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.
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Use TMP 01 and get the temerature i degrees Kelvin. Zero is realy zero.

Pelle
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