Passive buzzer on pin 8, on an Arduino Uno

// Passive buzzer on pin 8: a C major scale, one note at a time.
//
//   pin 8   the buzzer's + leg
//   GND     the buzzer's other leg
//
// A passive buzzer has no oscillator inside, so a steady HIGH only clicks it
// once. tone(pin, frequency) makes the pin swing up and down that many times
// a second, and the buzzer turns the swinging into a note: 262 Hz is middle C,
// and each octave up doubles it.
//
// The scale climbs C D E F G A B C, then waits a second and starts again.
// Change the numbers in NOTES to play something else.

const int BUZZER = 8;
const int NOTES[] = {262, 294, 330, 349, 392, 440, 494, 523};
const char *NAMES[] = {"C5", "D5", "E5", "F5", "G5", "A5", "B5", "C6"};
const int COUNT = 8;
const int NOTE_MS = 500;

void setup() {
  Serial.begin(9600);
  Serial.println("Mokxi Uno: passive buzzer on pin 8");
}

void loop() {
  for (int i = 0; i < COUNT; i++) {
    Serial.print(NAMES[i]);
    Serial.print(" ");
    Serial.print(NOTES[i]);
    Serial.println(" Hz");
    tone(BUZZER, NOTES[i], NOTE_MS);
    delay(NOTE_MS + 50);
  }
  delay(1000);
}