How to Use MKE-S07 MQ-3 Alcohol Sensor: Examples, Pinouts, and Specs

The MKE-S07 MQ-3 Alcohol Sensor is an electronic component designed to detect alcohol gas in the air. It is widely used in various applications such as breathalyzers, alcohol detection systems in vehicles, and other safety devices where the presence of alcohol needs to be monitored. The sensor's high sensitivity to alcohol makes it an ideal choice for projects that require reliable alcohol detection.

• Sensor Type: Semiconductor
• Detection Gas: Alcohol, Ethanol
• Concentration Range: 0.04mg/L to 4mg/L alcohol in the air
• Supply Voltage: 5V ±0.1
• Heating Voltage: 5V ±0.1 (AC or DC)
• Load Resistance: Adjustable
• Heater Resistance: 31Ω±3Ω (at room temperature)
• Heating Consumption: about 750mW
• Operating Temperature: -10°C to 50°C
• Sensitivity: Sensitive to alcohol fumes

To use the MKE-S07 MQ-3 Alcohol Sensor in a circuit:

1. Connect the heater pins (H) to a 5V power supply.
2. Connect the ground pin (B) to the ground of the power supply.
3. The analog output pin (A) provides a voltage that is proportional to the concentration of alcohol gas in the air. Connect this pin to an analog input on a microcontroller, such as an Arduino, to read the sensor output.

• Preheat Time: Before taking accurate readings, the sensor requires a preheat time of at least 24 hours initially and 48 hours for optimal performance.
• Calibration: The sensor needs to be calibrated in clean air or against a known alcohol concentration to set a baseline for measurements.
• Load Resistance: Adjust the load resistance to calibrate the sensor for different concentration ranges.
• Avoid Harsh Conditions: Do not expose the sensor to high concentrations of alcohol for long periods, as this may damage the sensor.
• Temperature and Humidity: Be aware that the sensor's readings can be affected by temperature and humidity.

// MQ-3 Alcohol Sensor Example Code for Arduino UNO

const int MQ3AnalogPin = A0; // MQ-3 sensor analog output connected to A0

void setup() {
  Serial.begin(9600); // Start serial communication at 9600 baud rate
}

void loop() {
  int sensorValue = analogRead(MQ3AnalogPin); // Read the sensor output
  float voltage = sensorValue * (5.0 / 1023.0); // Convert to voltage
  Serial.print("Sensor Voltage: ");
  Serial.println(voltage); // Print the voltage to the Serial Monitor
  delay(1000); // Wait for 1 second before reading again
}

• Inaccurate Readings: If the sensor provides inconsistent or inaccurate readings, ensure that it has been properly preheated and calibrated.
• No Output: Check the connections and ensure that the sensor is receiving the correct supply voltage.

• Preheating: Always preheat the sensor before use.
• Calibration: Regularly calibrate the sensor to maintain accuracy.
• Avoid Contaminants: Keep the sensor away from smoke, dust, and other contaminants that may affect its performance.

Q: How long does the MQ-3 sensor last? A: With proper use and maintenance, the MQ-3 sensor can last for several years.

Q: Can the MQ-3 sensor detect other gases? A: The MQ-3 is primarily designed to detect alcohol fumes, but it may also respond to other gases like benzene or methane, albeit with less sensitivity.

Q: Is the MQ-3 sensor suitable for professional breathalyzers? A: The MQ-3 sensor is suitable for educational and hobbyist projects. For professional applications, more accurate and reliable sensors are recommended.

Q: How do I know if the sensor is heated properly? A: The sensor's heater will typically reach a stable resistance value when it is properly heated. This can be verified with a multimeter.

Remember to provide adequate ventilation when using the sensor, as the presence of alcohol fumes can be hazardous. Always follow safety guidelines when working with electronic components and sensors.