Features & Specifications
Operating Voltage: 5V±0.1
Heating voltage: 5V±0.1
Load Resistance: 2 Kohms
Sensing Resistance Range: 10 – 60 Kohms
CH4 Sensing Range: 300 – 10000 ppm
Sensor Heat Consumption: ≤ 950 mW
Relative Humidity: >95% RH
Standard Oxygen concentration: 21%
Output Analog Voltage: 2.5 – 4 Volts (5000 ppm CH4)
Preheating Time: Over 48 Hours
The sensor is a simple and stable circuit with a TTL DO pin
 
MQ-4 Working Principle
As soon as the module is powered, the power LED lights up. The MQ-4 works by sensing the methane concentration in the air. The analog pin of the sensor then generates an analog signal proportional to the amount of CH4 in the air. We can measure the analog output of a sensor with an ADC microcontroller.
Microcontroller reads the analog output signal of the methane gas sensor and performs signal conditioning to convert the measured analog voltage into Methane concentration in air. Based on this measurement, we can take proper actions such as alarm triggering, etc. whatever you have coded for it to do.
Similarly, the same goes for the digital output pin of the MQ4 methane sensor. When methane gas is detected, the digital pin goes HIGH and the Digital output inbuilt led glows up. This digital pin can also be used for different activities being commanded by a microcontroller.