piezoelectric buzzer is an integrated unit consisting of a combination of a piezoelectric diaphragm with a feedback electrode, and a drive circuit.
In contrast, a piezoelectric sounder (self drive type) consists of only a piezoelectric diaphragm with a feedback electrode. It is used in combination with an external drive circuit.
The drive circuit for both of the above is a simple circuit consisting of one transistor and three resistors. When a DC voltage V is applied to the drive circuit, the oscillation conditions in the circuit are satisfied in the vicinity of the resonant frequency. As a result, the piezoelectric diaphragm is driven at the oscillation frequency, causing it to emit a sound.
Regarding the drive circuit for a piezoelectric sounder (self drive type), we set a standard circuit for each product. For details, please refer to our catalog.
When you add a series resistor between the DC voltage V and the piezoelectric buzzer in order to adjust the sound pressure of the buzzer, insert a capacitor (of about 1 mF) in parallel with the piezoelectric buzzer. This is effective for preventing irregular oscillation.