Piezoelectric speaker

A piezoelectric buzzer. The white ceramic piezoelectric material can be seen fixed to a metal diaphragm.
When fixed to a metallic diaphragm and excited with an alternating voltage, the diameter of the disc varies by a small amount, this causes dishing of the diaphragm which gives a much louder sound.

A piezoelectric speaker (also known as a piezo bender due to its mode of operation, and sometimes colloquially called a "piezo", buzzer, crystal loudspeaker or beep speaker) is a loudspeaker that uses the piezoelectric effect for generating sound. The initial mechanical motion is created by applying a voltage to a piezoelectric material, and this motion is typically converted into audible sound using diaphragms and resonators. The prefix piezo- is Greek for 'press' or 'squeeze'.[1]

Compared to other speaker designs piezoelectric speakers are relatively easy to drive; for example they can be connected directly to TTL outputs, although more complex drivers can give greater sound intensity. Typically they operate well in the range of 1-5 kHz and up to 100 kHz in ultrasound applications.

  1. ^ Platt, Charles (2012). Encyclopedia of electronic components. Volume 1, [Power sources & conversion : resistors, capacitors, inductors, switches, encoders, relays, transistors]. Sebastopol CA: O'Reilly/Make. p. 258. ISBN 978-1-4493-3387-4. OCLC 824752425.