Lesson 22 Buzzer¶
Introduction
A buzzer is an audio signaling device. Buzzers can be categorized into active and passive ones (see as below).
Components
1 * SunFounder Uno board
1 * USB data cable
1 * Active buzzer
1 * Passive buzzer
2 * 3-Pin anti-reverse cable
Principle
Place the pins of two buzzers face up and you can see the one with a green circuit board is a passive buzzer, while the other with a black tape, instead of a board, is an active buzzer, as shown below.
Active buzzer Passive buzzer
An active buzzer has a built-in oscillating source, so it will make sounds when electrified. But a passive buzzer does not have such source, so it will not beep 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.
The schematic diagram:
Experimental Procedures
Step 1: Build the circuit
Passive Buzzer
Step 2: Open the code file (Passive)
Step 3: Select correct Board and Port
Step 4: Upload the sketch to the SunFounder Uno board
Code
Now, you can hear the passive buzzer beeping. It also works in the same way if you use an active one here.
Active Buzzer
Note
The active buzzer has a built-in oscillating source, so it will beep as long as it is wired up.
Step 2: Open the code file (Active)
Step 3: Select correct Board and Port
Step 4: Upload the sketch to the SunFounder Uno board
Code
Now, you can hear the active buzzer beeping. But it won’t work if you use a passive one here.