This is a simple-to-use [Carbon Monoxide (CO)](http://en.wikipedia.org/wiki/Carbon_monoxide) sensor, suitable for sensing CO concentrations in the air. The MQ-7 can detect CO-gas concentrations anywhere from 10 to 500ppm.
This sensor has a high sensitivity and fast response time. The sensor’s output is an analog resistance. The drive circuit is very simple; all you need to do is power the heater coil with 5V, add a load resistance, and connect the output to an ADC.
This sensor comes in a package similar to our MQ-3 alcohol sensor, and can be used with the breakout board below.