This is a very simple weekend project: A gas leakage alarm for your kitchen.

It's based on a MQ-2 sensor, which detects LGP (Liquefied Petroleum Gas), alcohol, smoke, propane and some other gases. It comes froma family of sensors, all of them with the same pinout, so any project using them can be easily "ported" to detect different gases. For example, MQ-7 detects Carbon Monoxide and ME2-O2 detects Oxigen.

This circuit uses an Arduino Pro mini, which is small enough to be enclosed on a small box near the stove. As LGP is denser than air, it tends to flow towards the ground. So, the box should be placed up to 30cm over the ground.

The sound alarm goes off over a buzzer, and a potentiomenter is available to adjust the sensibility.

Project code is available at my github repository