New sketches: UV, WaterMeter for Reed sensors, Air quality ...

  • Hero Member


    Lost posts, but the sketches are still here:

    • MQ135.ino : for CO2/COV ... validated
    • MQ2.ino : for ethanol... still ongoing...
    • PressureSensor.ino : validated, works well, too much temp reading given back
    • SoundSensor2.ino: not yet tested
    • UVsensor.ino : validated
    • WaterMeterPulseSensor2.ino : for use with water meter that have a reed switch, validated

    Next steps:

    • validate sound sensor
    • validate mq2 sensor (I dont smoke...hart to trigger...)
    • MQ6 sensor
    • MQ131 sensor
    • TGS2600 sensor

  • Hi, I bought these MQ sensors collection from ebay and soldered them on their boards.

    Connected them this way:
    Arduino VCC ---> MQ2 VCC
    Arduino GND ---> MQ2 GND
    Arduino A0 ----> MQ2 AOUT
    not connected ---- MQ2 DOUT

    I tried AirQuality.ino, MQ2.ino, and
    Serial monitor outputs 0ppm on every parameter. Tried blowing cigarette smoke in MQ2 with no luck.

    MQ2 PCB SMD board has four outputs like the one on the MySensors store , and it has a pot on it. Sketch from after calibration outputs R0 resistance (3.65kohm). Should I tune that pot to the point when the sketch outputs ~10kohm?

    I have read on Arduino playground that MQ sensors should have burn-in period (12-24 h) to make their readings more consistent. But if there are no readings I shold not expect readings from it.

    Does someone have any advice to get this sensor reading? Cheers, Dario.

  • Hero Member


    first the pot is only for the digital output, it has no effect on the analog one.

    second, check your wiring, the analog should always report something, make sure the analog you use in the sketch is the one wired ... basic mistake... same for the 5V and ground.

    there is also a led on the board, if the board is correctly powered at some moment the led should turn up.

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