The MQ-4 gas sensor is a semiconductor-based sensor that is highly sensitive to a wide range of combustible gases, including Methane (CH4) and Natural gas. It has a small sensitivity to alcohol and smoke. This sensor is known for its fast response and stable, long-lasting performance. The drive circuit is simple, making it easy to use.

In terms of specifications, the MQ-4 requires a power supply of 5V±0.1V, and it has a TTL digital output of 0 and 1 (0.1 and 5V), as well as an analog output of 0.1-0.3V (relative to pollution), with the maximum concentration of a voltage of about 4V. It is capable of detecting Natural gas/Methane concentrations from 200-10000ppm. The sensor also has a TTL compatible input (HSW) and output (ALR), and the heater consumption is less than 750mW. The operating temperature for the MQ-4 is 14 to 122°F (-10 to 50°C), with a related humidity less than 95%RH. The load resistance is 20KΩ, and the sensing resistance is 10KΩ-60KΩ (1000ppm CH4). It is recommended to have a preheat time of over 24 hours. The standard encapsulation is Bakelite with a metal cap.