The sensitive material of MQ-7 gas sensor adopts tin oxide (SnO2) with low conductivity in clean air. Using a simple circuit to change the conductivity, the gas concentration is converted into a corresponding output signal. The MQ-7 high sensitivity carbon monoxide gas sensor, the sensor can detect a variety of gases containing carbon monoxide, is a low-cost sensor. It adopts high-quality dual-panel design, with power indicator and TTL signal output indicator. Widely used in alarms household gas leak detectors, industrial combustible gas alarms and portable gas detectors. Input voltage: DC5V Power consumption (current): 150mA DO output: Digital TTL 0 and 1 (0.1 and 5 V) AO output: 0.1-0.3V (relative), high concentration voltage about 4V Special reminder: After the sensor is powered on, it needs to warm up for about 20 seconds before the data measured are not stable. It is normal for the sensor to heat up, because there is a heating wire inside, if it is hot, it will be abnormal Size: 32mm X width 22mm X height 27mm