Features:1. Using double-sided circuit board design, with power indicator and TTL signal output indicator.2. With DO switching signal (TTL) output and analog output AO.3. TTL output valid signal is low level. (When the output is low level, the signal light is on, it can be directly connected to the MCU or relay module)4. Analog output voltage, the higher the voltage, the higher the concentration.5. High sensitivity for the detection of alcohol gas.6. Rapid response and recovery characteristics.7. There are four screw holes for easy positioningDetailed Test Parameters:Model: MQ-3Detecting gas: alcohol vaporDetection concentration: 0.04-4mg/L alcoholStandard circuit condition: Loop voltage VC 24DCHeating voltage :VH 5.00.2V AC/DCLoad resistance: RL adjustableGas sensor characteristics under standard test condition: Heating resistor 313Heating power consumption: 90mWSensitive surface resistance: 2K-20K (in 0.4mg/L alcohol)Sensitivity: Rs (in air) / Rs (0.4mg / L alcohol) 5Concentration slope: 0.6 (R300ppm/R100ppm alcohol)Standard test conditions: 202; 65%5% RHStandard test circuit: 5.0V 0.1VWarm-up time: 48 hoursElectrical Properties:Input voltage: DC5VPower consumption (current ): 150mADO output: TTL digital 0 and 1 ( 0.1 and 3.3V)AO output: 0.1-0 .3V, the highest concentration voltage is about 4VNote: After the sensor is powered, needs to warm up around 20S, measured data was stable , heat sensor is a normal phenomenon , because the internal heating wire , if hot is not normal.Wiring:1. VCC: connected to the positive pole of the power supply2. GND: connected to the negative power supply3. DO: TTL switching signal output4. AO: analog signal outputPackage list:2 x Alcohol Gas Sensor