1.2.1 Active Buzzer¶
In this project, we will learn how to drive an active buzzer to beep with a PNP transistor.
In this project, we need the following components.
It’s definitely convenient to buy a whole kit, here’s the link:
ITEMS IN THIS KIT
You can also buy them separately from the links below.
In this experiment, an active buzzer, a PNP transistor and a 1k resistor are used between the base of the transistor and GPIO to protect the transistor. When the GPIO17 of Raspberry Pi output is supplied with low level (0V) by programming, the transistor will conduct because of current saturation and the buzzer will make sounds. But when high level is supplied to the IO of Raspberry Pi, the transistor will be cut off and the buzzer will not make sounds.
Step 1: Build the circuit. (The active buzzer has a white table sticker on the surface and a black back.)
Step 2: Open the code file.
Step 3: Run.
sudo python3 1.2.1_ActiveBuzzer.py
The code run, the buzzer beeps.
You can Modify/Reset/Copy/Run/Stop the code below. But before that, you need to go to source code path like
raphael-kit/python. After modifying the code, you can run it directly to see the effect.
import RPi.GPIO as GPIO import time # Set GPIO17 as buzzer pin BeepPin = 17 def setup(): GPIO.setmode(GPIO.BCM) GPIO.setup(BeepPin, GPIO.OUT, initial=GPIO.HIGH) def main(): while True: # Buzzer on (Beep) print ('Buzzer On') GPIO.output(BeepPin, GPIO.LOW) time.sleep(0.1) # Buzzer off print ('Buzzer Off') GPIO.output(BeepPin, GPIO.HIGH) time.sleep(0.1) def destroy(): # Turn off buzzer GPIO.output(BeepPin, GPIO.HIGH) # Release resource GPIO.cleanup() # If run this script directly, do: if __name__ == '__main__': setup() try: main() # When 'Ctrl+C' is pressed, the program # destroy() will be executed. except KeyboardInterrupt: destroy()
Set the buzzer pin as low level to make the buzzer beep.
Wait for 0.1 second. Change the switching frequency by changing this parameter.
Not the sound frequency. Active Buzzer cannot change sound frequency.
Close the buzzer.