Range hood automatic control circuit

Working principle: The gas sensor and W1 in the figure form a gas detection circuit, and the AC 5V voltage output by the power transformer heats the heating wire of the gas sensor. Inverters F1, W2, and thermistor Rt form a temperature detection circuit. The high-potential signals output by the two detection circuits control the motor control circuit composed of F2, F3, R2, VT2, and J1 through isolation diodes VD8 and VD9 respectively. Photoresistors CdS, W3, F4, R3, VT3, J2, etc. form a lighting control circuit; IC1 is a music alarm circuit, which is controlled by the gas detection circuit.

Component Selection IC1 uses KD9561 integrated circuit; F1~F4 uses CD4069 integrated circuit. VT1~VT3 all use 9013 transistors. Photoresistor uses CdS photoresistor; thermistor uses 4 330Ω thermistors in series. Gas sensor uses QM-N10. Other components are selected as shown in the figure.