Editing Buzzer (section)

== Types ==

===Electromechanical===
Early devices were based on an electromechanical system identical to an [[electric bell]] without the metal gong. Similarly, a [[relay]] may be connected to interrupt its own actuating [[Electric current|current]], causing the [[Switch|contact]]s to buzz (the contacts buzz at [[Utility frequency|line frequency]] if powered by [[alternating current]]) Often these units were anchored to a wall or ceiling to use it as a sounding board. The word "buzzer" comes from the rasping noise that electromechanical buzzers made.

===Mechanical===
A [[joy buzzer]] is an example of a purely mechanical buzzer and they require drivers. Other examples of them are doorbells.

===Piezoelectric===
[[File:2007-07-24 Piezoelectric buzzer.jpg|thumb|Piezoelectric disk beeper]]
A [[piezoelectric]] element may be driven by an [[Oscillation|oscillating]] electronic circuit or other [[audio signal]] source, driven with a [[piezoelectric audio amplifier]]. Sounds commonly used to indicate that a button has been pressed are a click, a ring or a beep.

[[File:Buzzer interior.JPG|thumb|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.]]

A piezoelectric buzzer/beeper also depends on acoustic cavity resonance or [[Helmholtz resonance]] to produce an audible beep.<ref>{{Cite web | url=http://www.puiaudio.com/resources-white-papers-helmholtz.aspx |title = Design of a Helmholtz Chamber - PUI Audio &#124; A Projects Unlimited Company located in Dayton, Ohio}}</ref>