Component knowledge
Thermistor
Thermistor is a temperature sensitive resistor. When the temperature changes, resistance of thermistor will
change. With this feature, we can use thermistor to detect temperature intensity. Thermistor and symbol are
as follows.
The relationship between resistance value and temperature of thermistor is:
Rt=R*EXP [B*(1/T2-1/T1)]
Where:
Rt is the thermistor resistance under T2 temperature;
R is in the nominal resistance of thermistor under T1 temperature;
EXP[n] is nth power of E;
B is for thermal index;
T1, T2 is Kelvin temperature (absolute temperature). Kelvin temperature=273.15+celsius temperature.
Parameters of the thermistor we use is: B=3950, R=10k, T1=25.
The circuit connection method of the thermistor is similar to photoresistor, like the following method:
We can use the value measured by the analog pin of UNO to obtain resistance value of thermistor, and then
can use the formula to obtain the temperature value.
Consequently, the temperature formula can be concluded:
T2 = 1/(1/T1 + ln(Rt/R)/B)
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