Buzzer / Piezo
Transducer
A component that converts electrical signals into sound. Piezo buzzers use the piezoelectric effect to create a high-pitched tone.
Schematic symbol
Buzzer
How buzzer / piezo appears in a circuit diagram.
Types & variants
Key specs
Operating voltage
V DCVoltage required for proper operation. Active buzzers have a fixed voltage, passive ones work with varying voltages.
Frequency
HzSound pitch produced. Piezos typically range from 2kHz to 5kHz.
Current draw
mAHow much current it consumes at rated voltage. Active buzzers draw more than passive ones.
Sound pressure level
dBLoudness of the buzzer at 10cm distance. Higher values are louder.
Markings
Usually labeled with voltage, current, and frequency. Active buzzers often have a '+' marking for positive polarity.
Standard values
Operating voltage: 3V, 5V, 12V, 24V. Frequency: 2kHz, 3kHz, 4kHz. Common dB ratings: 70-85dB.
How to choose
1) Determine if active or passive is needed for your circuit. 2) Check voltage compatibility with your system. 3) Select appropriate frequency and loudness for your application. 4) Consider current draw if power is limited.
Pinout & package
2-pin configuration. Active buzzers are polarized (+/-), passive are non-polarized. Common packages: round metal can with pins, PCB-mount plastic cases, SMD versions.
Example circuits
- Alarm system indicator
- Device power-on notification
- Microcontroller output (PWM for passive buzzers)
- Electronic musical instrument
Common failures
Open circuit (no sound) from broken internal connections, reduced volume from aging piezo element, or short circuit. Physical damage like cracks or water ingress can cause failure.
How to test
1) For active buzzers: Apply rated voltage, should produce continuous tone. 2) For passive buzzers: Apply AC signal (1-5kHz), should produce sound. 3) Check continuity across pins - active buzzers may show some resistance, passive may show open circuit.
Substitutes
Different voltage or frequency rating of buzzer. Speaker with driver circuit for more complex sounds. Relay with mechanical bell for very loud applications.