Read relative ethanol-vapor changes from an MQ-3 only after warm-up and calibration; the module is not a legal breath tester or certified safety instrument.
Engineering approach
Read relative ethanol-vapor changes from an MQ-3 only after warm-up and calibration; the module is not a legal breath tester or certified safety instrument.
Implementation guidance
Use a stable heater supply, allow the specified burn-in and warm-up, record clean-air resistance, and calibrate with a known ethanol reference in controlled temperature and humidity. Read the analog channel as a trend unless a complete calibration model is available.
Scope and limitations
MQ-3 is cross-sensitive and its response changes with temperature, humidity, aging, airflow, and heater history. Never use a hobby module for legal alcohol testing or safety decisions.
Choose the required components and verify their specifications in the Juthour Tech store.
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