Alarm device
Videos
An alarm device is a mechanism that gives an audible, visual, combination, or other kind of alarm signal to alert someone to a problem or condition that requires urgent attention.
Fire alarm in Magnuson Park
A 2022 alarm system panel with devices linked to central
Buzzer
Videos
A buzzer or beeper is an audio signaling device, which may be mechanical, electromechanical, or piezoelectric. Typical uses of buzzers and beepers include alarm devices, timers, train and confirmation
Piezoelectric disk beeper
Interior of a readymade loudspeaker, showing a piezoelectric-disk-beeper (With 3 electrodes ... including 1 feedback-electrode ( the central, small electrode joined with red wire in this photo), and an oscillator to self-drive the buzzer.