Temperature compensation circuit composed of gas sensor and time delay circuit of positive temperature coefficient thermistor (R2) Time delay circuit of positive temperature coefficient thermistor (R2)

Temperature compensation circuit composed of gas sensing elements

Due to the characteristics of the gas sensor itself (temperature coefficient, humidity coefficient, initial stability, etc.), they should be taken into consideration when designing and making application circuits. For example, a temperature compensation circuit can be used to reduce the error caused by the temperature coefficient of the gas sensor; a delay circuit can be set to prevent false alarms caused by a large change in the resistance of the gas sensor at the beginning of power-on; a heater failure notification circuit can be used to prevent missed alarms caused by heater failure. The figure below is a temperature compensation circuit

Delay circuit of positive temperature coefficient thermistor (R2)

The figure below is a delay circuit of a positive temperature coefficient thermistor (R2). When the power is just turned on, its resistance value is also small, and most of the current returns to the transformer through the thermistor, and the buzzer (BZ) does not sound an alarm. After 1 to 2 minutes of power-on, the resistance value increases sharply, the current passing through the buzzer increases, and the circuit enters a normal working state.