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.
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.