The over temperature sensor circuit described here keeps a constant watch on the temperature level and gives an indication when the temperature level goes above a certain value. The temperaturse sensor circuit is simple and uses a CMOS IC CD4060(IC1). A standard PTC type thermistor works as the heat sensor.

Normally, the very low resistance of thermistor (TH1) makes the reset pin (pin12) of IC1 high, and the oscillator is disabled. When the temperature increases, high resistance of thermistor makes reset terminal of IC1 low and it starts oscillating and this condition is indicated by the flashing of the red color LED (D1). Using the 100K preset pot (P1) we can set the sensitivity of the sensor thermistor. Input supply for the circuit is 9 Volt DC.

Over Temperature Sensor Circuit Diagram

over temperature sensor circuit diagram