Gas Sensor Module | Carbon Monoxide Detection | MQ-7 for Arduino

This MQ-7 gas sensor module detects carbon monoxide (CO) in the air. It gives an analog voltage that changes with CO concentration. It also has a digital output for simple high/low alerts. This is a common CO sensor for electronics projects with Arduino. Features and Benefits - Dual Signal Output - Use the analog pin for exact measurement or the digital pin for a simple alarm. - Onboard Potentiometer - Adjusts the digital output's sensitivity without changing your code. - Wide Detection Range - Senses CO levels from 20 to 2000 parts per million (ppm). - Standard 4-Pin Header - Connects to breadboards and microcontrollers like Arduino or ESP8266. Applications - Building a carbon monoxide detector for a home, garage, or workshop. - Monitoring air quality as part of a larger environmental sensing station. - Adding a safety shut-off to projects that involve burning fuel. What You Need To test a flame sensor on a gas furnace, you will require a multimeter capable of measuring microamperes ($\mu\text{A}$). Ensure your multimeter has fresh batteries for accurate readings. You may also need a screwdriver to access the furnace's internal components. For cleaning a dirty flame sensor, 400 grit sandpaper is recommended. Understanding how a gas sensor, specifically an electrochemical sensor, functions is beneficial for interpreting readings. Method 1: Testing Active Signal Strength ($\mu\text{A}$) This method focuses on measuring the current generated by the flame sensor when it is exposed to flame. A healthy flame sensor, which is a type of gas sensor, typically produces a signal in the microampere range. Readings outside the expected range often indicate a fault with the sensor itself or a problem with the gas furnace's combustion. This test helps determine if the sensor is accurately detecting the presence of a flame.