Alcohol tester suite mq-3 drink-driving tester MQ-3 module alcohol sensor DIY parts

Brand Name:icchipcn.com
Condition:New
Type:Voltage Regulator
Application:Computer
Supply Voltage:1
Dissipation Power:1
is_customized:Yes

Function: alcohol concentration alarm circuit this circuit is mainly an alarm control circuit formed by mq-3 of the gas-sensitive sensor group. When alcohol vapor exists in the environment where the sensor mq-3 is located, the conductivity of the sensor will increase with the increase of alcohol vapor concentration. The alcohol content in the environment can be determined by measuring the series partial voltage between the sensor and the fixed resistance.

Working voltage: 5-7.5v dc

PCB size: 6.2*3.6cm

Circuit description:

This circuit can be powered by 5-7.5v dc power supply, switch S1 is the power switch, resistance R1 and led D1 are used for power indication, sensor mq-3 needs to be heated to a certain temperature when working, so there is a section of electric heating wire installed inside, resistance R4 is the current limiting resistance of the electric heating wire, after power on, mq-3 heating is normal phenomenon. When mq-3 does not detect alcohol vapor, its internal resistance is very large, R3, RW voltage drop is very low, the 2-pin voltage of NE555 is lower than the trigger voltage (VCC/3), its 3-pin output high level, D2 off, the buzzer does not sound, the relay does not operate. When mq-3 detects the alcohol vapor, the internal resistance drops, R3 and RW voltages rise, the voltage of the 2pin of NE555 is higher than the trigger voltage, the 3pin becomes a low level, D2 conducts luminescence, the buzzer begins to sound when it flows through the current, and the electromagnetic coil in the relay is energized to attract the switch action. So as to achieve detection and alarm function. The adjustable resistor RW is used to adjust the detection sensitivity. This circuit USES the second comparator inside NE555 to detect the voltage change and USES its internal trigger to eliminate the chatter. The seven and five feet of the NE555 are unused and suspended. The output terminal J3 of the relay can be used to control other electrical appliances, such as the exhaust fan. When the alcohol concentration exceeds the standard, the exhaust fan will be started. When the concentration drops, the exhaust fan will be closed to realize automatic control. Diode D3 is used to eliminate the induction electromotive force generated when the relay coil is on and off. The power supply interface can be DC plug, or the line can be directly in J2 position, pay attention to the positive and negative sign, DC plug power supply positive and negative outside.