Encyclopedia of Electronic Components Volume 2

Chapter 28. audio indicator

sound source

audio alert

audio indicator

An audio indicator is defined here as a noise-creation device that generates a simple tone or series of tones. Unlike a transducer, which requires an external source of AC to determine its audio frequency, an indicator contains its own electronics and requires only a DC power supply. Either of these components is often described as a beeper or buzzer.

While piezoelectric alerts formerly used crystals, only the more modern piezoelectric type that uses a ceramic wafer will be considered here.

Other related components

• transducer (see Chapter 27)

• headphone (see Chapter 29)

• speaker (see Chapter 30)

What It Does

When DC power is applied to an audio indicator, in its ...