N° of component 

Temperature to Pulse Width Converter (CB1487E)

  This circuit was obtained in a 1977 technical documentation. The sensor is a thermistor from 10k to 50k and the transistor may be a BC548. The circuit converts the sensor temperature to pulse width. The variation is approximately 25 us per degree with the original sensor. The maximum width is 650 us. The components can be changed to other frequencies and pulse duration.

Circuit Bench