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Doorbell with a Buzzer

A doorbell that plays a four-note "ding-dong" on a passive buzzer when you press the button; every ring is also written to the Serial Monitor. It teaches making sound with tone(), keeping notes and their lengths in arrays and playing them with a for loop, gathering a job into its own function, and reading a button with the Arduino's built-in pull-up resistor (INPUT_PULLUP). You can make the tune your own by changing the notes in the code. No extra library needed.

What you need

• 1 × Arduino Uno R3
• 1 × Breadboard 830 Points (MB-102)
• 1 × Passive Buzzer (Piezo)
• 1 × 12x12 mm Push Button
• 5 × Jumper Wire - Male/Male

Wiring steps

1. 1

   Connect the common ground (GND)

   

   Plug a black jumper wire into the GND pin next to pin 13 on the Arduino's digital header. Connect its other end to the breadboard's top blue (−) rail. The button's and the buzzer's ground wires will go into this rail too.

   • Arduino GND → the top blue (−) rail (black wire)
2. 2

   Add and wire the button

   

   Seat the button over the middle gap of the breadboard: two legs in the top half and two in the bottom half, in columns 5 and 7. Connect the Arduino's pin 2 to column 5 in the bottom half with a green jumper wire (BUTTON_PIN 2). Then connect column 7 in the top half to the top (−) rail with a short black wire. Because you use two diagonal legs of the button, it works whichever way round it sits; no extra resistor is needed either, the Arduino's built-in one (INPUT_PULLUP) is enough.

   • push button → across the middle gap, columns 5 and 7
   • Arduino pin 2 → column 5, bottom half (green wire)
   • column 7, top half → the top blue (−) rail (black wire)
3. 3

   Add and wire the buzzer

   

   Plug the passive buzzer's + leg into column 15 in the top half and its other leg into column 16; the + leg is usually the longer one and the body has a + mark. Connect the Arduino's pin 8 to column 15 with an orange jumper wire (BUZZER_PIN 8). Then connect column 16 to the top (−) rail with a short black wire. A passive buzzer makes no sound on its own: tone() switches the pin on and off hundreds of times a second, and the buzzer vibrates at that rate, which is the note you hear.

   • buzzer + leg → column 15, top half
   • buzzer − leg → column 16, top half
   • Arduino pin 8 → column 15, top half (orange wire)
   • column 16, top half → the top blue (−) rail (black wire)

Arduino sketch

// The button's and the buzzer's pins
const int BUTTON_PIN = 2;
const int BUZZER_PIN = 8;

// The bell's notes (Hz): E, C, D, G
const int MELODY[] = {659, 523, 587, 392};
// How long each note lasts (ms)
const int DURATIONS[] = {400, 400, 400, 800};
const int NOTE_COUNT = 4;

int rings = 0;

void setup() {
  // Pull-up: a pressed button reads LOW
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(BUZZER_PIN, OUTPUT);
  Serial.begin(9600);
  Serial.println("Doorbell ready: press the button");
}

// Plays the notes one after another
void playMelody() {
  for (int i = 0; i < NOTE_COUNT; i++) {
    tone(BUZZER_PIN, MELODY[i], DURATIONS[i]);
    // Let it end, then a short pause
    delay(DURATIONS[i] + 50);
  }
  noTone(BUZZER_PIN);
}

void loop() {
  if (digitalRead(BUTTON_PIN) == LOW) {
    rings++;
    Serial.print("Ring: ");
    Serial.println(rings);
    playMelody();

    // Wait until the button is let go
    while (digitalRead(BUTTON_PIN) == LOW) {
      delay(10);
    }
    // Let the contacts settle on release
    delay(50);
  }
}

What the Serial Monitor shows

Doorbell ready: press the button
Ring: 1
Ring: 2
Ring: 3

What you will see

Every press makes the buzzer play a four-note "ding-dong" (E, C, D, G), and the Serial Monitor shows how many times it has rung. Holding the button down does not ring it again; let go and press again. If there is no sound at all, check that the buzzer is a passive one and its + leg is in column 15 (the same column as pin 8's wire). If text reaches the Serial Monitor but there is no sound, the problem is on the buzzer's side; if nothing happens when you press the button, check that it sits over the middle gap, the green wire is in column 5 and the black wire in column 7.