MQ-3 Alcohol & Ethanol Gas Sensor Module

The module is simple to use and provides both analog and digital outputs, making it compatible with a wide range of microcontrollers like Arduino, ESP32, and Raspberry Pi.

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How It Works

The core of the module is the MQ-3 sensor, which uses a sensitive material (SnO₂ – Tin Dioxide). This material has low electrical conductivity in clean air. When alcohol gas is present, the sensor’s conductivity increases in proportion to the gas concentration.

The module’s built-in circuitry, featuring an LM393 comparator, processes this change and provides two types of outputs:

1. Analog Output (AOUT): A continuous voltage that is proportional to the concentration of alcohol detected.
2. Digital Output (DOUT): A simple HIGH/LOW signal that triggers when the alcohol concentration exceeds a specific level.

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Key Features

• High Sensitivity: Specifically designed to detect alcohol (ethanol) vapor with a fast response time.
• Dual Output: Provides both a real-time analog voltage (for measuring concentration) and a digital (HIGH/LOW) output.
• Adjustable Sensitivity: An onboard potentiometer (blue knob) allows you to easily set the threshold for the digital (DOUT) output.
• Status LEDs:
  • Power LED: Confirms that the module is powered on.
  • Digital Output LED: Lights up when the alcohol concentration crosses the set threshold.
• Wide Detection Range: Capable of detecting alcohol concentrations from 0.05 mg/L to 10 mg/L.
• Simple 4-Pin Interface: Easy to connect to any microcontroller.

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Common Applications

• DIY Breathalyser: Create your own device to test breath alcohol levels.
• Vehicle Safety Systems: Design a car ignition interlock that checks for alcohol.
• Portable Alcohol Detectors: Build a handheld device for testing.
• Environmental Monitoring: Monitor air quality for alcohol-based fumes.
• Robotics: Add “smelling” capabilities to a robot to detect alcohol.

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Pinout

• VCC: 5V DC Power Supply
• GND: Ground
• AOUT (AO): Analog Output (Connects to a microcontroller’s analog input pin)
• DOUT (DO): Digital Output (Connects to a microcontroller’s digital input pin)

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Technical Specifications

• Operating Voltage: 5V DC
• Target Gas: Alcohol (Ethanol)
• Detection Range: 0.05 mg/L to 10 mg/L
• Sensor: MQ-3
• Comparator Chip: LM393
• Preheat Time: 20-30 seconds (for stable readings)
• Dimensions: 32mm x 22mm