Simple thermistor temperature-to-frequency converter based on an astable multivibrator
Dragan K. Stankovic · Journal of Physics E Scientific Instruments · 1973
It is shown that the collector-coupled astable multivibrator whose one base resistor is replaced by a thermistor represents a temperature-to-frequency converter whose characteristic can be linearized in the given temperature range. The linear coefficient of the characteristic of the practical converter in the range 20-50 degrees C is beta =2.4% degrees C -1 , with linearity to within +or-0.25 degrees C and dependence on the ambient temperature of less than 0.027% degrees C -1 .