User Manual

Table Of Contents

VMP502

V. 02 – 25/10/2019 19 ©Velleman nv

6.6 Buzzer

Required Hardware

• 1 x Raspberry Pi

• 1 x breadboard

• 1 x buzzer (active)

• 1 x PNP transistor (8550)

• 3 x 1 kΩ resistor

• jumper wires as needed

An electronic buzzer is widely used in computers, alarms, electronic toys, etc.

Buzzers can be categorized as active or passive. An active buzzer has a built-in oscillating source, so it will

make sounds when electrified. A passive buzzer does not have an oscillating source and will not buzz if DC

signals are used. Instead, you need to use square waves whose frequency is between 2K and 5K to drive it. The

active buzzer is often more expensive than the passive one because of multiple built-in oscillating circuits.

Here, an active buzzer is used. When the GPIO output is supplied with low level (0 V) by programming, the

transistor will conduct because of current saturation and the buzzer will make a sound. When a high level is

supplied to the IO of the Raspberry Pi

, the transistor will be cut off and the buzzer will not make a sound.