SainSmart MQ131 Ozone Gas Detection Sensor Module

Hi, these little guys are MQ-2 and MQ-5 gas sensors. They look identical and you can probably tell them apart only by the labels. Both require exactly the same connections, but they detect different gases. In this tutorial I'll show you how to use one of them with Arduino. We'll be reading values from the sensor and make the Arduino light an LED when gas concentration rises above certain level. To build this project you'll need a few things: a 5V DC power supply that can deliver at least 0.3A, an MQ-2 or MQ-5 gas sensor, an Arduino board, a breadboard, a few wires, an LED, a 120 ohm resistor, a resistor close to 20k, a piece of heat shrink tubing and a gas lighter or torch. Let's start playing with the sensor. A gas sensor has 6 pins. These 2 middle legs are heater coil pins. Don't worry about polarity, it's not important in this sensor. The next 2 legs are A pins and they should be con