This is MQ-7 Carbon Monoxide Sensor. It detects the concentrations of CO gas in the air and outputs it`s reading as an analog voltage.
The sensor has a long life ,high sensitivity and fast response time. The sensor output signal is an analog resistance.
The sensor can measure a low concentration of carbon dioxide in the air. The sensitivity range of the gas concentration from 20ppm to 2000ppm. The sensor can operate in temperatures from -10 to 50 ° C, and consumes less than 150mA at 5V.
There are two modifications of the sensor:
Standard - with sensitivity.
With analog and digital outputs - with the amplifier output signal and adjusting the heating element sensor. You can configure the sensor to a certain threshold, and connect to the digital input of the microcontroller.