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