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Alcohol wine Tester Kit MQ-3 Wine Driving Tester MQ-3 Module Alcohol Sensor DIY Parts


Alcohol concentration alarm circuit, This circuit is mainly composed of gas sensor MQ-3 alarm control circuit, when the sensor MQ-3 environment in the presence of alcohol vapor, sensor conductivity will increase with the increase of alcohol vapor concentration. The alcohol content in the environment can be determined by measuring the series partial pressure between the sensor and the fixed resistance.


Working voltage: 5-7.5V DC
PCB size: 6.2*3.6cm


This circuit can be used for power supply.5-7.5 V DC power supply, switch S1 as power switch, resistance R1 and light-emitting diode D1 for power instructions, the sensor MQ-3 needs to be heated to a certain temperature when working, so its internal installation of a section of heating wire, resistance R4 as the current limiting resistance of the heating wire, MQ-3 heating after power on is normal. When MQ-3 does not detect alcohol vapor, its internal resistance is very large, R3, RW voltage drop is very low, NE555 2 feet voltage is lower than the trigger voltage (VCC/3), its 3 feet output high level, D2 extinguished, buzzer silent, relay does not operate. When MQ-3 detects alcohol vapor, the internal resistance decreases, the voltage of R3 and RW rises, the voltage of 2 feet of NE555 is higher than the trigger voltage, 3 feet become low level, D2 turn on light, buzzer current begins to sound, electromagnetic coil turns on the attraction switch in the relay. So as to realize the function of detection and alarm. The adjustable resistor RW is used to adjust the detection sensitivity. The circuit uses a second comparator inside the NE555 to detect voltage changes and uses its internal trigger to eliminate jitter. NE555's 7 feet and 5 feet are not in use. They are in a state of suspension. The output J3 of the relay can be used to control other electrical appliances, such as the exhaust fan, start the exhaust fan when the alcohol concentration exceeds the standard, and close the exhaust fan after the concentration drops to realize automatic control. Diode D3 is used to eliminate induction electromotive force when relay coil is broken. The power supply interface can be DC plug, also can be directly in the J2 position with wire, pay attention to the positive and negative signs, DC plug power supply inside and outside the positive and negative.