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1.2.1 Active Buzzer

Introduction

In this project, we will learn how to drive an active buzzer to beep with a NPN transistor.

Required Components

In this project, we need the following components.

Schematic Diagram

In this experiment, an active buzzer, an NPN transistor, and a 1kΩ resistor are used. The resistor is connected between the GPIO pin and the transistor’s base to limit the base current and protect the transistor. When GPIO17 on the Raspberry Pi outputs a high level (3.3V), the transistor enters saturation mode, allowing current to flow through the buzzer, which then sounds. When the GPIO17 outputs a low level (0V), the transistor is turned off, and the buzzer remains silent.

T-Board Name	physical	wiringPi	BCM
GPIO17	Pin 11	0	17

../_images/1.2.1_active_buzzer_schematic.png

Experimental Procedures

Step 1: Build the circuit. (The active buzzer has a white table sticker on the surface and a black back.)

../_images/1.2.1_ActiveBuzzer_circuit.png

Step 2: Open the code file.

cd ~/davinci-kit-for-raspberry-pi/python-pi5

Step 3: Run.

sudo python3 1.2.1_ActiveBuzzer.py

The code run, the buzzer beeps.

Warning

If there is an error prompt RuntimeError: Cannot determine SOC peripheral base address, please refer to If gpiozero doesn’t work.

Code

Note

You can Modify/Reset/Copy/Run/Stop the code below. But before that, you need to go to source code path like davinci-kit-for-raspberry-pi/python-pi5. After modifying the code, you can run it directly to see the effect.

#!/usr/bin/env python3
from gpiozero import Buzzer
from time import sleep

# Initialize a Buzzer object on GPIO pin 17
buzzer = Buzzer(17)

try:
    while True:
        # Turn on the buzzer
        print('Buzzer On')
        buzzer.on()
        sleep(0.1)  # Keep the buzzer on for 0.1 seconds

        # Turn off the buzzer
        print('Buzzer Off')
        buzzer.off()
        sleep(0.1)  # Keep the buzzer off for 0.1 seconds

except KeyboardInterrupt:
    # Handle KeyboardInterrupt (Ctrl+C) for clean script termination
    pass

Code Explanation

These statements import the Buzzer class from the gpiozero library and the sleep function from the time module.
```
#!/usr/bin/env python3
from gpiozero import Buzzer
from time import sleep
```
This line creates a Buzzer object connected to GPIO pin 17 on the Raspberry Pi.
```
# Initialize a Buzzer object on GPIO pin 17
buzzer = Buzzer(17)
```

In an infinite loop (while True), the buzzer is turned on and off every 0.1 seconds. print statements provide a console output for each action.

try:
    while True:
        # Turn on the buzzer
        print('Buzzer On')
        buzzer.on()
        sleep(0.1)  # Keep the buzzer on for 0.1 seconds

        # Turn off the buzzer
        print('Buzzer Off')
        buzzer.off()
        sleep(0.1)  # Keep the buzzer off for 0.1 seconds

This segment ensures the program can be terminated safely using a keyboard interrupt (Ctrl+C) without throwing an error.
```
except KeyboardInterrupt:
# Handle KeyboardInterrupt (Ctrl+C) for clean script termination
pass
```