I bought one of these:

1Pcs New Sound Detection Sensor Module Voice Sensor for Arduino Best

There are 3 pins on it:

  • 5V
  • GND
  • OUT

My guess is that OUT is an analogue signal that I can measure with my Arduino, am I right?

I am using the "Analogue Output" example code but I just get 5V all the time, it does not seems to change with the sound levels.

Am I doing something wrong? What am I adjusting with the blue square on the board? Should I maybe do that?

  • Output should be +5V with no sound and 0V with sound. The AnalogInOutSerial example should display on your monitor wit values close to mx for no speech and close to ground for speech present. Commented Feb 3, 2015 at 5:40

1 Answer 1


The wording on this particular eBay item is pretty poor but there are plenty of similar products with better descriptions that are photographically identical... example that make a little bit more sense.

Anyway, I don't think this gives an analog value output, the LM393 is a comparator, so I think the blue dial sets the 'threshold level' and any sounds over that level cause a logic low. i.e. it compares the audio level and the dial and when one exceeds the other it gives a signal.

The features also say "The output effective signal is low level" which is probably Chinglish for the signal is a logic low, i.e. when the sound is heard it goes to 0V rather than 5V which is what I think you were expecting.

In summary: This device is is more like a Clapper, it detects a loud noise and sends a digital low signal.

Try making a loud noise with the same setup you already have, and if not try adjusting the potentiometer by turning it, but not too far! It probably only turns 180-270º.

  • Sound good, I will try to change potentiometer and check the output. Is it easy to turn it too far?
    – rablentain
    Commented Feb 2, 2015 at 23:50

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