2 Pack MQ-135 Air Quality and Hazardous Gas Detection Sensor Alarm Module for Arduino

Description : Sensitive material MQ135 gas sensor is used in clean air low conductivity tin oxide (SnO2). When the sensor is kept in their environment Module Applications: suitable to ammonia , aromatic compounds , sulfur compounds , benzene vapor , smoke and other gases harmful gases , the gas sensitive element concentration range : 10 to 1000ppm Module Features : 1 , using high-quality dual-panel design, with power indicator and TTL signal output instructions; 2 , the switching signal having a DO (TTL) output and analog output AO ; 3, TTL output valid signal is low . ( Low-level signal when the output light can be directly connected to the microcontroller or relay module ) 4 , the higher the voltage , the concentration of the analog output voltage is higher. 5 , air quality , hazardous gas detection with good sensitivity . 6 , there are four screw holes for easy positioning ; 7 , has a long life and reliable stability 8 , rapid response and recovery characteristics Electrical properties: Input voltage : DC5V Power consumption ( current ): 150mA DO output : TTL digital 0 and 1 ( 0.1 and 5V) AO output :0.1-0 .3 V ( relative to pollution ) , the maximum concentration of a voltage of about 4V Special note: After the sensor is powered , needs to warm up around 20S, measured data was stable , heat sensor is a normal phenomenon , because the internal heating wire , if hot is not normal . Wiring: 1, VCC: positive power supply (5V) 2, GND: power supply is negative 3, DO: TTL switching signal output 4, AO: analog signal output