Adopt high-quality double-panel design, with power indicator and TTL signal output indicator. With DO switch signal (TTL) output and AO analog signal output TTL output high and low level. (Can be directly connected to the microcontroller or relay module) The analog output voltage changes with the concentration. Fast response feature. Has long service life and stability. Electrical performance: Input voltage: DC5V Power consumption (current): 150mA DO output: TTL digital quantities 0 and 1 (0.1 and 5V) AO output: analog level signal reminder: After the sensor is powered on, it needs to be preheated for about 20S, and the measured data is stable. It is normal for the sensor to heat up, because there is a heating wire inside, if it is hot, it will not be normal. Wiring: 1. VCC: connect to the of the power supply (5V) 2. GND: connect to the negative of the power supply 3. DO: TTL switch signal output 4, AO: analog signal output Material:Metal colour: green Package Contents: 1 x MQ131 High Concentration Sensor Only the above package content, other are not included. Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.