MQ9 DC 5V Combustible Gas and Carbon Monoxide CO Sensor Module Overview A compact, easy to integrate gas sensor module for detecting carbon monoxide CO and common combustible gases. Designed for DIY, prototyping, and embedded monitoring systems, this MQ9 module runs from DC 5V and provides both analog and digital outputs for flexible interfacing. Key benefits Detects multiple gases: Sensitive to carbon monoxide CO and combustible gases such as methane and LPG, enabling broad monitoring with a single sensor. Simple integration: Works with common microcontrollers and single board computers, including Arduino and Raspberry Pi, via standard analog and digital signals. Adjustable sensitivity: Onboard potentiometer and comparator allow tuning the digital threshold to match application requirements. Ready to use at DC 5V: Powered by a single 5 volt supply without additional electronics. Compact form factor: Small PCB module fits easily into enclosures and prototypes where space is limited. Durable sensing element: Metal oxide semiconductor sensor provides repeatable response for routine monitoring tasks. Key features and specifications Model: MQ9 sensor module Supply voltage: DC 5V Outputs: Analog voltage output for concentration sensing, digital TTL output from onboard comparator Onboard controls: Sensitivity adjustment potentiometer and indicator LED Sensor type: Metal oxide semiconductor gas sensor element suitable for CO and combustible gases Interface pins: VCC, GND, AO (analog out), DO (digital out) Typical uses: Gas leak detection, air quality monitoring in enclosed spaces, prototype integration with microcontrollers How it solves common problems Detects presence and approximate concentration of hazardous gases so you can trigger alarms or ventilation in automated systems. Provides both analog and digital outputs so it can be used for logging concentrations or for immediate thresholdbased alarms. Compact, low voltage design makes it easy to add gas sensing to existing electronic projects without redesigning power systems. Practical applications Home or workshop monitoring: Integrate with a microcontroller to sound an alarm or activate ventilation when CO or combustible gas is detected in a kitchen, garage, or workshop. Embedded prototypes and robotics: Add gas sensing to IoT prototypes, environmental sensing stations, or robotics projects to provide situational awareness. Educational and laboratory projects: Use in classroom experiments and lab projects to demonstrate gas detection principles and to develop alarm and data logging systems. Integration tips Allow a preheat period per sensor datasheet recommendations before taking critical readings to stabilize the sensing element. Use the analog output for concentration tracking and the digital output for simple threshold alarms. Calibrate the digital comparator using the onboard potentiometer to match the desired trigger level for your application. What is included MQ9 gas sensor module with MQ9 sensing element mounted on a PCB with comparator and potentiometer. This MQ9 DC 5V sensor module provides a practical, lowcost way to add carbon monoxide CO and combustible gas detection to electronics projects and monitoring systems.