3pcs Electronic DIY Kit MQ-3 Sensor Alcohol Detector Tester Alarm System Components Suite

Module function Alcohol concentration alarm when the ambient alcohol gas solubility exceeds the set threshold the buzzer will alarm the red light will be on and the relay will act This circuit is mainly an alarm control circuit composed of the gas sensing sensor group MQ 3 When there is alcohol vapor in the environment where the sensor MQ 3 is located the conductivity of the sensor will increase as the alcohol vapor concentration increases By measuring the partial pressure in series between the sensor and the fixed resistor the alcohol content in the environment can be determined The probe needs to be warmed up for 1 minute so it will work normally after 1 minute of power on Working voltage 5 7 5V DCMain components MQ3 smoke sensor LM358 integrated chipModule size 36 59mm length width Circuit description This circuit can be powered by 5 7 5 volt DC power supply resistor R5 and light emitting diode D2 are used for power indication The sensor U1 MQ3 needs to be heated to a certain temperature during work so a piece of heating wire is installed inside it It needs to be warmed up for 1 minute after power on and then it works normally after 1 minute so it is normal for MQ 3 to generate heat after power on Resistor R9 is the current limiting resistance of the heating wire When MQ 3 does not detect alcohol vapor its internal resistance is very large and the pressure drop of R6 and R7 is very low The voltage of pin 5 of LM358 is lower than the voltage