What Is a Buzzer? Active vs Passive Buzzers and Playing Melodies with Arduino

A buzzer is a tiny speaker that turns an electrical signal into sound. The beep of an alarm system, a microwave's alert and the tunes in toys usually come from a buzzer. In Arduino projects it's the cheapest way to give audible feedback, but to get the right sound you need to know which type of buzzer you have.

Active vs passive buzzer

How do you tell whether a buzzer is active or passive?

• Look at the bottom: a passive buzzer usually shows a green circuit board underneath; an active buzzer's bottom is sealed with black filler.
• Apply 5 V: an active buzzer beeps continuously, a passive one only gives a faint click when you connect it.
• Measure with a multimeter: a passive buzzer's coil shows a low, steady resistance of around 16 Ω; an active one gives an unclear or very high reading.
• Check the sticker: active buzzers often have a protective sticker on top that says "remove".

Connecting a buzzer to Arduino

Small buzzers draw about 20–30 mA, so they can connect directly to an Arduino pin. Connect the long leg (+) to a digital pin, for example pin 8, and the short leg to GND. If it's too loud, you can add a resistor of around 100 Ω. Larger, stronger buzzers need to be driven through a transistor.

Playing notes and melodies with tone()

With a passive buzzer, tone(pin, frequency, duration) generates a square wave at the requested frequency. Every note has a frequency; for example A4 is 440 Hz:

const int BUZZER_PIN = 8;   // pasif buzzer / passive buzzer

// Do Re Mi Fa Sol La Si Do
int notes[] = {262, 294, 330, 349, 392, 440, 494, 523};

void setup() {
  for (int i = 0; i < 8; i++) {
    tone(BUZZER_PIN, notes[i], 300); // 300 ms çal / play for 300 ms
    delay(350);                      // notalar arası boşluk / gap between notes
  }
  noTone(BUZZER_PIN);                // sesi kapat / stop the sound
}

void loop() {
}

Common mistakes

• Expecting a melody from an active buzzer: its built-in oscillator produces a fixed tone; tone() doesn't change the pitch.
• Using PWM on pins 3 and 11 together with tone(): on the Uno, tone() uses Timer2, so analogWrite on these pins misbehaves while it plays.
• Playing two buzzers at once: tone() works on only one pin at a time.
• Reversing the polarity: the long leg is positive; connected backwards, an active buzzer stays silent.

To build a button piano, start with How to Connect a Push Button to Arduino, and to set the pitch or volume with a knob, see What Is a Potentiometer?.