This simple GAS Sensor breakout board designed by Tenet Technetronics in such a way that can work with any of the MQ-series gas sensor, like MQ-3, MQ-4, MQ-6, MQ-7, etc gas sensors. This breakout board simplifies the interface from 6 to 4 pins that are broken out with a 0.1″ spacing, making the board compatible with 0.1″ headers to standard breadboards. The board has a diameter of 16.8 mm, which matches the diameter of the small (plastic) gas sensor packages, providing a more convenient, compact connection within the bounds of the sensor itself.
The two rows of 1 x 2 pins are spaced 0.5″ apart allowing the break out board to work with standard breadboards.
Connect H1 and A1 to 5 V, GND to ground, and B1 to an ADC input of your microcontroller. A required (but not included) sensitivity-setting resistor, RL, should be connected between B1 and GND. The resistance of RL should be calculated using the datasheet for your particular gas sensor.
The MQ gas sensors have light to no polarity, so the gas sensor will work with the board any way it fits into the 6 pins.