The MQ-3 Alcohol Sensor is a versatile device that detects various gases, including alcohol, benzine, hexane, and LPG, in the air. Primarily used as a breathalyzer, it accurately measures the presence of alcohol after consumption. Operating on 5V DC with low power consumption, it offers both analog and digital outputs. With its fast response, high sensitivity, and wide detection range, this sensor provides reliable and stable performance. It features a simple drive circuit, a potentiometer to adjust sensitivity, and a preheat duration of 20 seconds. 

 

Package Includes:

• 1x MQ3 Alcohol Sensor Module

 

Features:

• Wide Gas Detection Range: The module is sensitive to a variety of gases, including alcohol, benzine, hexane, and LPG (liquefied petroleum gas).
• Operating Voltage: It operates on a 5V DC power supply.
• Power Consumption: The module consumes approximately 800mW of power.
• Analog Output: The module provides an analog output voltage ranging from 0V to 5V, which can be utilized for measuring gas concentration.
• Digital Output: The module also offers a digital output voltage that follows TTL (Transistor-Transistor Logic) logic, where it outputs either 0V or 5V.
• Preheat Duration: It has a preheat duration of 20 seconds, allowing the sensor to reach an optimal operating state quickly.
• Digital and Analog Sensing: The module can be used as either a digital or analog sensor, providing flexibility in different applications.
• Sensitivity Adjustment: The sensitivity of the digital pin can be adjusted using a potentiometer, allowing users to fine-tune the sensor based on their specific requirements.
• Wide Detecting Scope: It has a broad detecting range, capable of detecting alcohol concentrations ranging from 25 to 500 parts per million (ppm) in the air.
• Fast Response and High Sensitivity: The module exhibits a rapid response time and high sensitivity to gas concentrations, ensuring accurate and timely detection.
• Stable and Long Life: It features a simple drive circuit that ensures stable performance and a long operational lifespan.

 

Description:

The MQ-3 Alcohol Sensor is a highly sensitive device capable of detecting various gases, including alcohol, benzine, hexane, and LPG, present in the air. While commonly used as a breathalyzer, it provides accurate readings for individuals who have consumed alcohol, whether it be beer, wine, or other alcoholic beverages. Operating on 5V DC power with a power consumption of approximately 800mW, the MQ-3 sensor offers versatile functionality. It can be utilized as both a digital and analog sensor, providing flexibility in different applications. The analog output voltage ranges from 0V to 5V, while the digital output voltage operates on TTL logic, producing either 0V or 5V. With a quick preheat duration of 20 seconds, the MQ-3 sensor rapidly reaches an optimal operating state. The sensitivity of the digital pin can be adjusted using the integrated potentiometer, allowing for fine-tuning based on specific requirements. The sensor boasts a wide detection scope, offering reliable results within a concentration range of 25 to 500 ppm of alcohol in the air. It demonstrates fast response times, high sensitivity, and stability, ensuring accurate readings for a prolonged period. The device incorporates a simple drive circuit, contributing to its longevity and reliability. For sensors that have recently been used, a warm-up period of only 5-10 minutes is necessary to achieve optimal performance. However, if the sensor has been stored for an extended period, particularly a month or more, it should be warmed up for 24-48 hours to ensure maximum accuracy when used again.

 

Principle of Work:

The MQ-3 Alcohol Sensor operates by utilizing a heating element and a detecting element to effectively recognize alcohol in the environment. To ensure safety, the sensor is designed with two thin layers of stainless steel mesh that separate the heating element from the alcohol vapors. This configuration prevents any potential explosions by keeping the alcohol and hot elements apart. The sensor consists of two main parts: the heating element and the detecting element. The heating element is constructed using nichrome wire, while the detecting element is made of platinum wire coated in tin dioxide. The heating element is responsible for creating a controlled temperature environment within the sensor, enabling accurate detection of alcohol vapors. For optimal performance, the MQ-3 sensor requires calibration, especially if it has been stored for a long time. Due to its heater-driven nature, the sensor needs to be properly warmed up for 24-48 hours before usage after a lengthy storage period of a month or more. This extended warm-up period ensures maximum accuracy in alcohol detection. However, if the sensor has been recently used, it will reach its full operational state within 5-10 minutes. During the warm-up phase, the sensor may initially provide high readings, which gradually decrease until it stabilizes. The 48-hour warm-up period is particularly necessary for obtaining precise measurements of alcohol concentration. In addition to proper warm-up, achieving accurate results requires reliable sensor calibration and accounting for other environmental factors such as temperature and humidity. By implementing these mechanisms, the MQ-3 Alcohol Sensor ensures effective and safe detection of alcohol vapors, making it a valuable tool in applications such as breathalyzers and gas concentration monitoring systems.

 

Pinout of the Module:

Pin Name	Description
VCC	supplies power for the module. You can connect it to 5V output from your Arduino.
GND	is the Ground Pin and needs to be connected to the GND pin on the Arduino.
D0	provides a digital representation of the presence of combustible gases.
A0	provides analog output voltage is proportional to the concentration of smoke/gas.

• The MQ-3 Gas and Smoke Sensor Module is equipped with four pins, two of which are dedicated to VCC (power supply) and Gnd (ground), while the remaining two provide simultaneous analog and digital data output. The module operates within a 5V voltage range with a tolerance of 0.1%. To power the circuit, the Arduino's 5V port is typically used.
• This module incorporates two internal LEDs, visible in the accompanying image. The power LED illuminates when the board is powered up, indicating its operational status. Additionally, the doubt LED lights up when the signal surpasses the trigger value set by the potentiometer.
• The gas sensor's analog input signal is converted to a digital signal on the module using an integrated comparator OP-Amp. This conversion process enables easy interfacing with digital systems and further data processing. To fine-tune the sensitivity of the module, a Trim-pot (trimming potentiometer) is provided, allowing users to adjust the device's response according to their specific needs.
• The module also incorporates a set of resistors and capacitors, serving the purpose of decoupling and filtering. These components aid in stabilizing the power supply and minimizing noise interference, ensuring reliable and accurate measurements.
• With its straightforward pin configuration, voltage compatibility, integrated LEDs, adjustable sensitivity, and filtering components, the MQ-3 Gas and Smoke Sensor Module offers a convenient and versatile solution for gas and smoke detection applications.

 

Applications:

1. Breathalyzer Devices: The module is commonly used in breathalyzer devices to detect alcohol vapors in breath, enabling the measurement of blood alcohol concentration.
2. Gas Leak Detection: It can be employed for detecting gas leaks in residential, commercial, or industrial settings, providing an early warning system for potentially hazardous situations.
3. Air Quality Monitoring: The module can be utilized in air quality monitoring systems to measure the presence of gases and smoke in indoor or outdoor environments, ensuring a healthy and safe living or working space.
4. Fire Alarm Systems: It can be integrated into fire alarm systems to detect the presence of smoke, enabling timely alerts and evacuation in case of fire incidents.
5. Industrial Safety: The module is suitable for industrial environments where the presence of specific gases or smoke needs to be monitored to ensure worker safety and comply with occupational health regulations.
6. Smart Homes: It can be integrated into smart home systems to provide real-time monitoring of gas levels, enabling automation and safety features such as automatically shutting off gas supplies in case of leaks.
7. Environmental Monitoring: The module can be employed in environmental monitoring projects to measure the concentration of gases and smoke in natural habitats or specific areas, aiding in pollution control and research.
8. Personal Safety Devices: These can be incorporated into wearable or portable gas detection devices to provide individuals with personal safety against harmful gas exposure in various environments.

 

Circuit:

To connect the MQ3 Gas Alcohol Sensor to an Arduino follow these instructions:

1. Connect the sensor's analog output pin (AO) to analog input pin 0 (A0) on the Arduino.
2. Connect the sensor's digital output pin (DO) to digital input/output pin 8 (D8) on the Arduino.
3. Connect an LED to digital pin 13 (D13) on the Arduino. The longer leg (anode) of the LED should be connected to D13, and the shorter leg (cathode) should be connected to GND (ground) on the Arduino.
4. Connect the Arduino board to your computer using a USB cable.

 

Library:

This Module doesn't need any Library to function.

 

Code:

With this code, you can successfully connect the MQ3 Gas Alcohol Sensor to the Arduino and monitor the sensor values on the serial monitor while controlling an LED based on the digital input from the sensor.

const int MQ3pin = A0;  // Analog input pin for MQ3 sensor
const int ledPin = 13;  // Digital output pin for LED
const int digitalPin = 8;  // Digital input pin for MQ3 sensor

void setup() {
  pinMode(ledPin, OUTPUT);  // Set LED pin as output
  pinMode(digitalPin, INPUT);  // Set digital input pin for MQ3 sensor
  Serial.begin(9600);  // Initialize serial communication
  Serial.println("MQ3 warming up!");
  delay(20000);  // Allow the MQ3 to warm up
}

void loop() {
  int sensorValue = analogRead(MQ3pin);  // Read analog input from MQ3 sensor

  Serial.print("Sensor Value: ");
  Serial.println(sensorValue);
  
  if (digitalRead(digitalPin) == HIGH) {
    digitalWrite(ledPin, HIGH);  // Turn on the LED if digital input is HIGH
  } else {
    digitalWrite(ledPin, LOW);  // Turn off the LED if digital input is LOW
  }
  
  delay(2000);  // Wait for 2 seconds before the next reading
}

• The constants MQ3pin, ledPin, and digitalPin are defined at the beginning to represent the respective pin numbers. The pinMode() function is used to set the LED pin as an output and the digital input pin for the MQ3 sensor as an input.
• The code reads the analog input from the MQ3 sensor using analogRead() and stores the value in the sensorValue variable. The sensor value is then printed to the serial monitor. The if statement checks if the digital input from the MQ3 sensor is HIGH using digitalRead(). If it is HIGH, indicating the threshold has been reached, the LED is turned on with digitalWrite(). Otherwise, the LED is turned off.
• A delay of 2 seconds is added using delay() before the next reading to provide a time gap between measurements.

 

Technical Details:

Operating Voltage	4.9-5.1V
Detecting Concentration	0.05-10mg/L
Current Consumption	150mA
DO Output	TTL digital 0 and 1
AO Output	0.1-0.3V
Load Resistance	200kΩ
Heater Resistance	33Ω
Heater Consumption	less than 750mW
Operating Temperature	-10 to 50°C
Dimensions:	36 x 20 x 21 mm (LxWxH)
Heater voltage:	5±0.2V (AC•DC)
Weight:	6gm

 

Resources:

tutorial

 

Comparisons:

The MQ2 and MQ3 gas sensors are both part of the MQ series and are commonly used for gas detection purposes. While they share similarities, they also have distinct characteristics. Let's compare the MQ2 and MQ3 sensors in various aspects:

1. Sensitivity:

   • MQ2: The MQ2 sensor is highly sensitive to gases such as LPG, propane, hydrogen, methane, and smoke.
   • MQ3: The MQ3 sensor is primarily sensitive to alcohol vapor, making it suitable for breathalyzer applications and detecting the presence of alcohol in the air.

2. Target Gases:

   • MQ2: The MQ2 sensor can detect a range of gases, including alcohol, LPG, propane, hydrogen, methane, and smoke.
   • MQ3: The MQ3 sensor is specifically designed to detect alcohol vapor, making it less suitable for detecting other gases.

3. Applications:

   • MQ2: The MQ2 sensor is widely used in gas leakage detection, fire detection systems, home safety devices, and air quality monitoring where a variety of gases need to be detected.
   • MQ3: The MQ3 sensor is commonly used in breathalyzer devices, alcohol detection systems, and applications that require monitoring alcohol levels.

4. Sensing Principle:

   • MQ2: The MQ2 sensor utilizes a dual-heating element and a semiconductor gas-sensitive material to detect target gases based on their conductivity changes.
   • MQ3: The MQ3 sensor operates on the principle of a tin dioxide (SnO2) semiconductor sensing element, which exhibits variations in resistance when exposed to alcohol vapor.

5. Sensing Range:

   • MQ2: The MQ2 sensor can detect gases within a certain concentration range depending on the gas being detected.
   • MQ3: The MQ3 sensor is designed to detect alcohol vapor within a concentration range of approximately 25 to 500 ppm (parts per million).

When choosing between the MQ2 and MQ3 sensors, consider the specific gas you need to detect, the sensitivity required, and the target application. If you require the detection of various gases, including alcohol, the MQ2 sensor may be more suitable. However, if alcohol vapor detection is your primary focus, the MQ3 sensor offers greater sensitivity in that specific area.