The MQ-5 gas sensor board is a semiconductorbased sensing module designed for the detection of liquefied petroleum gas (LPG) and other combustible gases such as propane, methane, and butane. Due to its broad sensitivity profile, the sensor is well suited for general gas leak detection, gas alarm systems, and safetyrelated monitoring applications. The typical detection range spans from 50 to 10,000 ppm.

The module operates from a 5 V DC supply and integrates the required heater circuitry for stable sensor operation. Gas concentration is evaluated via an analog voltage output in the range of 0 to 5 V, derived from the change in sensing resistance. In addition, a digital output is provided via an onboard comparator with an adjustable threshold, allowing direct use in alarm or switching applications without external signal conditioning.

After each power-up, the sensor requires a heatup time of approximately 10 to 15 minutes before reliable measurements can be obtained. For initial commissioning, a burn-in period of 48 to 168 hours of continuous operation is recommended to stabilize the sensing element. Following this period, a baseline resistance measurement in clean air should be recorded as a reference value. If the sensor has been powered off for several weeks or longer, repeating the burn-in and baseline procedure is advised to maintain measurement consistency.

The board is equipped with power and status LEDs for visual indication of operation and detection status. For mechanical and layout flexibility, the LEDs may alternatively be soldered on the opposite side of the PCB. Electrical interfacing is provided via a 4-pin 2.54 mm header and a Molex PicoBlade connector, enabling straightforward integration into embedded systems, microcontroller platforms, and gas detection devices.