[discontinued] MQ-135 Air Quality Sensor Hazardous Gas Detection Sensor

DESCRIPTION The main chip: LM393, MQ135 gas sensing probe Operating voltage: DC 5V     A hazardous gas detection apparatus for the family, the environment, suitable for ammonia, aromatic compounds, sulfur, benzene vapor, smoke and other gases harmful gas detection, gas-sensitive element test concentration.    Air quality sensor is for detecting a wide range of gases, including NH3, NOx, alcohol, benzene, smoke and CO2. Ideal for use in office or factory, simple drive and monitoring circuit.   FEATURE     1. Signal output indicator instructions;    2. Dual signal output (analog output, and TTL level output);    3. TTL output valid signal is low; (output low signal light, which can be accessed microcontroller IO port)    4. Analog output with increasing concentration, the higher the concentration, the higher the voltage;    5. Sulfide, benzene Department of steam, smoke and other harmful gases with high sensitivity;    6. Has a long life and reliable stability;    7. Rapid response rec