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Circuit 03 - Buzzers

Background​

In this circuit, we'll again bridge the gap between the digital world and the analog world. We'll be using a buzzer that makes a small "click" when you apply voltage to it (try it!). By itself that isn't terribly exciting, but if you turn the voltage on and off hundreds of times a second, the buzzer will produce a tone. And if you string a bunch of tones together, you've got music! This circuit and sketch will play a classic tune. We'll never let you down!

Parts List​

NameQuantity
LED (Any colour)1
330Ω Resistor (Orange-Orange-Brown)1
Jumper Wire7
Push Button1
10kΩ Resistor (Black-Brown-Orange)1
Buzzer1

Circuit Diagram​

Breadboard Diagram​

Code​

Here's the code:

int numOfNotes = 8;
int melody[] = {262, 196, 196, 220, 196, 0, 247, 26};
int durations[] = {4, 8, 8, 4, 4, 4, 4, 4};

void setup() {
  pinMode(11, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(2, INPUT);
}

void loop() {
  if (digitalRead(2) == HIGH) {
    digitalWrite(11, HIGH);
    for (int i = 0; i < numOfNotes; i++) {
      int duration = 1000 / durations[i];
      tone(8, melody[i], duration);
      int pause = duration * 1.30;
      delay(pause);
       noTone(8);
    }
  } else {
    digitalWrite(11, LOW);
  }
}

What You Should See​

You should see - well, nothing more than what you should see in project 2! But you should be able to hear a song. If it isn't working, make sure you have assembled the circuit correctly and verified and uploaded the code to your board, or see the troubleshooting tips below.

Troubleshooting​

No Sound?​

Given the size and shape of the piezo buzzer, it is easy to miss the right holes on the breadboard. Try double-checking its placement.

Musical Tone​

NoteG3A3B3C4D4E4F4G4A4B4C5
Freq (Hz)196220247262294330349392440494523

Real World Application​

Many modern megaphones have settings that use a loud amplified buzzer. They are usually very loud and quite good at getting people’s attention.

The Code Explained​

CodeExplanation
int numOfNotes = 8; Declaring an integer (whole number) variable to remember the number of notes.
int melody[] = { ... }int melody[] stores an array or list of all the notes to be played.
int noteDurations[] = { ... }```int noteDurations[] stores a list of the length of the notes to be played. The number of elements or items in each array must match. A note duration of 1 corresponds to a whole note, a duration of 2 is a half note, a duration of 4 is a quarter note, and a duration of 8 corresponds to an eighth note.
for(...) { This is a for() loop. We won't go into the details of its function here, but we use it to play our tune.
tone(8, freq, length);The tone function is used to play a tone with a buzzer. The first value is the pin the buzzer is attached to, the second value is the frequency, and the last value is the duration of the tone.

Exercise​

  1. Modify the code to play the following tune: Tone: E4, D4, C4, D4, E4, E4, E4, D4, D4, D4, E4, G4, G4 Duration: 4, 4, 4, 4, 4, 4, 2, 4, 4, 2, 4, 4, 2 Hint: You'll need to change the numOfNotes variable. What is the tune?
  2. Play the tune faster by a factor of 2.
  3. Modify the code so the LED blinks with the tone instead of always ON when the tone is playing.
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Circuit 02 - Push ButtonsCircuit 04 – Potentiometers