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HUM: Sound detector module

You are a beginner with Croduino. Or electronics? A specific module caught your eye, but you do not know how to use it? Do not worry, HUM is here for you! How to Use Module (HUM) is a blog tutorials series by e-radionica where you will find all you need in order to begin working with your favorite module. Tutorials include: technical characteristics, work principle, instructions on how to connect module with Croduino and the basic code. Everything else is left to your imagination.

Basic characteristics

The sound detector module is the module which sends a signal through a digital output when it detects a sound. While detecting, it sends a LOW signal and illuminates the signal LED diode embedded on the module. It can be used for acustic light control and similar sound control or simply as a sound detector.


Voltage: 4V-6V
Dimensions: 3.8 x 1.6 x 1.0 cm
Weight: 4g

Work principle

The basic part of the module is a small condensing microphone which turns the sound  energy into electric energy. These microphones consist of a membrane (made of electret material) and solid panel. The titration of the membrane changes the gap between the electrodes, which affects the change of the capacity or the electrical voltage. When there are no detected sounds the output module logic is HIGH and vice versa. The module has a built-in signaling LED that illuminates when the module detects a sound.

On the module, there is also LM393 analogue voltage comparator which functions as a small voltmeter with integrated switches. It measures voltage in two different points and compares the difference. If the voltage in the first point is higher than that of the second one, the switch is on. In reverse, the switch is off. The comparison voltage is adjusted using built-in potentiometer on the module, using which we decide when the module will send LOW signal via digital output pin. This allows us to use module even without logic controllers.

How to connect module with Croduino

Vcc - 5V
gnd - gnd
out - digital pin 2

Module code

The principle is very uncomplicated.  The module sends LOW signal via the digital OUT pin onto the Croduino, which detects vibration or impulse (given the sensibility we have set on the potentiometer). To apply this we can use the code that comes with Arduino IDE "DigitalReadSerial", and find it in:

File - Examples - Basic - DigitalReadSerial

Each 1ms, it reads the status of the digital pin 2 and prints the value (0 for LOW, 1 for HIGH)  in SerialMonitor.

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