SENSORS/ACTUATORS

INTERNET OF THING (IoT)

Arduino Mega - Buzzer

This guide teaches you how to use the Arduino Mega to make a 12V active buzzer loud. If you need to work with a 5V active or passive buzzer, read our Arduino Mega Piezo Buzzer tutorial.

There are two ways to drive the 12V buzzer. A relay is simple, but it clicks every time it switches. A MOSFET module does the same job with no sound, and it can switch very fast. This is good for alarm beeps. We will try both ways in this tutorial.

Hardware Preparation

1	×	Arduino MEGA
1	×	Alternatively, DIYables MEGA Development Board
1	×	USB 2.0 cable type A/B (for USB-A PC)
1	×	USB 2.0 cable type C/B (for USB-C PC)
1	×	Relay
1	×	Alternatively, MOSFET Module (AOD4184, LR7843 or FR120N)
1	×	12V Active Buzzer
1	×	12V Power Adapter
1	×	DC Power Jack
1	×	Jumper Wires
1	×	Recommended: Screw Terminal Block Shield for Arduino Uno/Mega
1	×	Recommended: Sensors/Servo Expansion Shield for Arduino Mega
1	×	Recommended: Breadboard Shield for Arduino Mega
1	×	Recommended: Enclosure for Arduino Mega

Or you can buy the following kits:

DIYables Sensor Kit (18 sensors/displays)

Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you.
Additionally, some of these links are for products from our own brand, DIYables .

Overview of 12V Active Buzzer

The 12V active buzzer makes a loud sound, good for alarm systems.

Pinout

A 12-volt active buzzer usually has two pins.

Connect the black wire to the power supply's ground (GND).
Connect the red wire to the power supply's +12V output.

How to Control 12V Active Buzzer

When a 12V active buzzer gets power from a 12V supply, it makes a sound. To run a 12V active buzzer with an Arduino Mega, put a relay between them. The Arduino Mega can turn the buzzer on and off through this relay. If you don't know much about relays (pin layout, how they work, or how to program them), check the Arduino Mega relay tutorial.

The MOSFET module is the second choice. The pins, the inside and the code of the module are explained in the Arduino Mega - MOSFET Module tutorial.

Relay vs MOSFET Module for a 12V Buzzer

	Relay	MOSFET Module
What it can do	turn the buzzer on or off	turn the buzzer on or off
Noise when switching	a click every time, mixed with the beep	no sound, you hear only the beep
How fast it switches	slow, a few milliseconds	very fast
Fast beeps	the relay clicks loudly and wears out fast	no problem
Life	the contacts wear out after many switches	nothing moves, so it lasts long
Type of power	AC or DC	DC only
Buzzer power supply	any voltage the relay is rated for	about 6V or more
Isolation from the Arduino	yes, between coil and contacts	yes, by the PC817 optocoupler
Good for	slow ON/OFF, like ON for a few seconds	alarm patterns with many short beeps

If the buzzer beeps slowly, the relay is fine. If you want an alarm with many short beeps, the MOSFET module is the better pick.

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

Arduino Mega Code

The code makes the 12V buzzer stay on for two seconds, then off for five seconds, and repeats.

/* * This Arduino Mega code was developed by newbiely.com * * This Arduino Mega code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-mega/arduino-mega-buzzer */ #define RELAY_PIN 3 // The Arduino Mega pin that controls the buzzer via relay // the setup function runs once when you press reset or power the board void setup() { // initialize digital pin D4 as an output. pinMode(RELAY_PIN, OUTPUT); } // the loop function runs over and over again forever void loop() { digitalWrite(RELAY_PIN, HIGH); // turn on buzzer 2 seconds delay(2000); digitalWrite(RELAY_PIN, LOW); // turn off buzzer 5 seconds delay(5000); }

Detailed Instructions

Follow these steps one by one.

Connect the parts as shown in the diagram.
Connect the Arduino Mega board to your computer with a USB cable.
Open the Arduino IDE on your computer.
Choose the correct board (Arduino Mega) and the COM port.
Paste the code into the Arduino IDE.
Click the Upload button in the Arduino IDE to send the code to your Arduino Mega.
Listen to the sound from the 12V active buzzer.

Code Explanation

The explanation is in the comments in the Arduino code shown above.

How to Make Alarm Beeps with MOSFET Module

Now let's replace the relay with a MOSFET module. The buzzer works the same, but there is no click, so it can beep fast like a real alarm.

Wiring Diagram

This image is created using Fritzing. Click to enlarge image

From	To
Arduino Mega pin 2	MOSFET module PWM
Arduino Mega GND	MOSFET module GND
12V adapter +	MOSFET module +
Buzzer red wire (+)	MOSFET module + (same terminal as the adapter +)
Buzzer black wire (−)	MOSFET module LOAD
12V adapter −	MOSFET module −

Most 12V active buzzers have a small circuit inside and do not need a flyback diode. If your buzzer is a magnetic type (it has a coil inside), add a 1N4007 or 1N5819 diode across it. The side with the stripe (cathode) goes to the buzzer +, the other side goes to the buzzer −.

Arduino Mega Code

/* * This Arduino Mega code was developed by newbiely.com * * This Arduino Mega code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-mega/arduino-mega-buzzer */ #define MOSFET_PIN 2 // The Arduino Mega pin connected to the PWM pin of the MOSFET module void setup() { Serial.begin(9600); pinMode(MOSFET_PIN, OUTPUT); digitalWrite(MOSFET_PIN, LOW); // start with the buzzer OFF } void loop() { // fast alarm beeps: 10 short beeps Serial.println("Alarm: fast beeps"); for (int i = 0; i < 10; i++) { digitalWrite(MOSFET_PIN, HIGH); // turn on buzzer delay(100); digitalWrite(MOSFET_PIN, LOW); // turn off buzzer delay(100); } // one long beep Serial.println("Alarm: long beep"); digitalWrite(MOSFET_PIN, HIGH); delay(1000); digitalWrite(MOSFET_PIN, LOW); // quiet time Serial.println("Quiet"); delay(3000); }

What the buzzer does: it beeps 10 times fast, then makes one long beep, then stays quiet for 3 seconds. Then it starts again.

An active buzzer makes its own sound. Only turn it fully ON or fully OFF with digitalWrite(). Do not use analogWrite() (PWM) to change the volume, because the sound will be weak or strange.

Detailed Instructions

Do the same setup as in the Quick Steps of the relay part above.
Wire the buzzer and the MOSFET module as shown in the diagram. Keep the 12V adapter unplugged.
Upload the code above to the Arduino Mega.
Plug in the 12V adapter.
Open the Serial Monitor at 9600 baud.
Listen to the buzzer: you hear the fast beeps with no relay click.

Newbiely | Arduino IDE 2.3.8

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Newbiely.ino

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8 Serial.println("Hello World!");

Output

Serial Monitor

Message (Enter to send message to 'Arduino Mega Or...' on 'COM15')

New Line

9600 baud

Alarm: fast beeps Alarm: long beep Quiet Alarm: fast beeps Alarm: long beep Quiet

Ln 11, Col 1

Arduino Mega Or... on COM15

※ NOTE THAT:

The MOSFET module works with DC only, and the buzzer power supply must be about 6V or more. For a 5V buzzer, see the Arduino Mega Piezo Buzzer tutorial. For an AC buzzer or siren, use the relay.

Video Tutorial

Learn More

Arduino Mega - Piezo Buzzer

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