Beep with an active buzzer

01Active vs passive

There are two kinds of small buzzer, and they look almost identical. Getting the right one matters:

This guide is for the active one. Two easy ways to spot it: it usually has a sticker on top and is a little taller, and it often has a + marked by one leg. If you flip it over and see a green circuit board with a copper coil, that's a passive buzzer — set it aside for now.

02What you need

• An active buzzer (the one with the sticker / + mark)
• An Arduino Uno + USB cable
• 2 jumper wires (male-to-female if you're plugging straight into the buzzer's legs)
• For the last example only: a pushbutton + 2 more wires

03Wiring it up

Just two wires. The buzzer has a long leg (+) and a short leg (−), exactly like an LED:

04Make it beep

Here's the whole idea: HIGH = beep, LOW = silence. This makes a short beep once a second:

const int BUZZER = 8;

void setup() {
  pinMode(BUZZER, OUTPUT);
}

void loop() {
  digitalWrite(BUZZER, HIGH);   // beep
  delay(200);                   // ...for 0.2 seconds
  digitalWrite(BUZZER, LOW);    // silence
  delay(800);                   // ...for 0.8 seconds, then repeat
}

That's genuinely all there is to an active buzzer. Everything else is just patterns of beeps and silences.

05SOS alarm

Same trick, more interesting timing. SOS in Morse code is three short beeps, three long beeps, three short beeps — ··· ——— ···. It uses the exact same timing rules as the LED Morse page, just sent to your ears instead of your eyes:

const int BUZZER = 8;

// Timing, all based on one "unit" (a dot length).
const int UNIT = 200;
const int DOT  = UNIT;          // short beep : 1 unit
const int DASH = UNIT * 3;      // long beep  : 3 units
const int GAP_SYMBOL = UNIT;     // silence between beeps
const int GAP_LETTER = UNIT * 3; // silence between letters

void setup() {
  pinMode(BUZZER, OUTPUT);
}

// One beep of a given length, then a short gap.
void beep(int ms) {
  digitalWrite(BUZZER, HIGH);
  delay(ms);
  digitalWrite(BUZZER, LOW);
  delay(GAP_SYMBOL);
}

void loop() {
  beep(DOT);  beep(DOT);  beep(DOT);    // S = ...
  delay(GAP_LETTER);
  beep(DASH); beep(DASH); beep(DASH);   // O = ---
  delay(GAP_LETTER);
  beep(DOT);  beep(DOT);  beep(DOT);    // S = ...
  delay(2000);                          // pause, then repeat
}

Want a faster or slower alarm? Change UNIT. Want a different message? Beep out any letters using the chart on the Morse page.

06Button-triggered beep

Now let's make it beep only when you say so. Add a pushbutton between pin 2 and GND — no resistor needed, because we'll use the Arduino's built-in one:

The buzzer stays exactly where it was (+ on pin 8, − on GND). Then:

const int BUZZER = 8;
const int BUTTON = 2;

void setup() {
  pinMode(BUZZER, OUTPUT);
  pinMode(BUTTON, INPUT_PULLUP);   // built-in resistor; not pressed = HIGH
}

void loop() {
  if (digitalRead(BUTTON) == LOW) {  // pressed pulls the pin LOW
    digitalWrite(BUZZER, HIGH);      // beep while held
  } else {
    digitalWrite(BUZZER, LOW);       // silent when released
  }
}

07If it won't beep

Next: the 1602A LCD →