The MQ-3 Alcohol & Ethanol Gas Sensor Module is a high-sensitivity semiconductor device designed to detect alcohol concentrations in the air. At Electrapac, we recommend this module for students and engineers in Bangladesh who are developing DIY breathalyzers, safety ignition interlocks, or industrial ethanol monitoring systems with Arduino and ESP32.

The MQ-3 uses a SnO2 (Tin Dioxide) sensitive layer which has lower conductivity in clean air. When alcohol gas is present, the sensor's conductivity increases in proportion to the gas concentration. This module provides both a Digital Output (DO) for simple threshold detection (e.g., an "Alcohol Detected" alarm) and an Analog Output (AO) for measuring precise concentration levels.

Key Features for Electrapac Customers

• Dual Output Modes: Use the Analog Pin to get a variable voltage that changes with alcohol intensity, or the Digital Pin to trigger a buzzer instantly when a limit is reached.

• On-Board Sensitivity Adjustment: Features a built-in potentiometer that allows you to calibrate the "trigger point" for the digital output without writing complex code.

• Fast Response & Recovery: Once exposed to alcohol, the sensor reacts within seconds, and its "recovery" time is optimized so you can perform multiple tests quickly.

• High Stability: Designed to have a long life and stable performance, even when used in humid environments or industrial workshops.

• Standard 4-Pin Interface: Easily connects to any microcontroller using standard jumper wires (VCC, GND, DO, AO).

To get accurate results from your Electrapac MQ-3 sensor, follow these essential steps:

1. The "Burn-In" Phase: New sensors require a one-time "burn-in" period where they stay powered on for 24–48 hours to stabilize the internal heating element.

2. Daily Pre-Heating: Every time you use the sensor, wait 60–120 seconds for the internal heater to reach the correct temperature. The module will feel warm to the touch—this is normal.

3. Calibration: Use the on-board potentiometer to set the "Threshold." Turn it until the status LED just turns off in clean air.

4. Analog Reading: Use analogRead(A0) on your Arduino. Higher values (closer to 1023) indicate a higher concentration of alcohol vapor.

Pro-Tip: For a more professional "Breathalyzer" feel, mount the sensor inside a 3D-printed tube or a small pipe. This ensures that the user's breath is concentrated directly onto the sensor surface for a consistent reading.

• DIY Breathalyzers: Building portable devices to estimate blood alcohol content (BAC) for educational purposes.

• Safety Ignition Interlocks: Creating prototypes that prevent a motor or machine from starting if alcohol is detected.

• Ethanol Monitoring: Detecting leaks in chemical laboratories or industrial spirit storage areas.

• Environmental Safety: Monitoring air quality in hospitals or pharmacies where ethanol-based cleaners are frequently used.

• Smart Home Alarms: Triggering an exhaust fan if high concentrations of cleaning vapors are detected in a room.

We source our MQ-3 Gas Sensors with high-quality heating elements to ensure they provide consistent analog readings over time. Visit us at www.electrapac.com for the environmental sensors that help you build a safer, smarter world.