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Project Notes

#455 PiezoBuzzers

Exploring techniques for driving piezo transducers and buzzer units for audio output.


Here’s a quick demo..



Piezoelectric sensors for generating sound are commonly found in two form factors:

  • a basic diaphragm/disk - can be used as a transducer as well as for sound generation
  • a buzzer unit in the familiar plastic cylinder


Driving Piezoelectric Disks

A common circuit for turning a Piezoelectric disk into a buzzer uses a low-side switch. Plain piezo disks require a bypass resistor to dump the charge (else no sound will be produced). Additional resistance can be added to limit current and reduce volume.

In the following test circuit, I have a 555 astable oscillator with variable resistor to generate a pulse from about 152 Hz to about 10kHz

The 555 output switched a low-side 2N7000 n-channel FET.

I’ve selected a 10kΩ bypass resistor. Lower values start to attenuate the output.

A 2.2kΩ series resistor limits current without much impact on volume.




Credits and References

About LEAP#455 OscillatorsCrystalAudio
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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is my personal collection of electronics projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

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