A buzzer or beeper is an

audio Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum *Digital audio, representation of sound ...

signaling device, which may be

mechanical Mechanical may refer to: Machine * Machine (mechanical), a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement * Mechanical calculator, a device used to perform the basic operations o ...

electromechanical Electromechanics combine processes and procedures drawn from electrical engineering and mechanical engineering. Electromechanics focus on the interaction of electrical and mechanical systems as a whole and how the two systems interact with each ...

, or

piezoelectric Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied stress (mechanics), mechanical s ...

(''piezo'' for short). Typical uses of buzzers and beepers include

alarm devices ALARM (Air Launched Anti-Radiation Missile) is a British anti-radiation missile designed primarily to destroy enemy radars for the purpose of Suppression of Enemy Air Defenses (SEAD). It was used by the RAF and is still used by the Royal Saudi ...

timer A timer or countdown timer is a type of clock that starts from a specified time duration and stops upon reaching 00:00. It can also usually be stopped manually before the whole duration has elapsed. An example of a simple timer is an hourglass ...

train A train (from Old French , from Latin">-4; we might wonder whether there's a point at which it's appropriate to talk of the beginnings of French, that is, when it wa ... , from Latin , "to pull, to draw") is a series of connected vehicles th ...

and confirmation of user input such as a mouse click or keystroke.

History

Electromechanical

The electric buzzer was invented in 1831 by

Joseph Henry Joseph Henry (December 17, 1797– May 13, 1878) was an American physicist and inventor who served as the first secretary of the Smithsonian Institution. He was the secretary for the National Institute for the Promotion of Science, a precursor ...

. They were mainly used in early

doorbell A doorbell is a signaling device typically placed near a door to a building's entrance. When a visitor presses a button (control), button, the bell rings inside the building, alerting the occupant to the presence of the visitor. Although the ...

s until they were phased out in the early 1930s in favor of musical chimes, which had a softer tone.

Piezoelectric

Piezoelectric buzzers, or piezo buzzers, as they are sometimes called, were invented by Japanese manufacturers and fitted into a wide array of products during the 1970s to 1980s. This advancement mainly came about because of cooperative efforts by Japanese manufacturing companies. In 1951, they established the Barium Titanate Application Research Committee, which allowed the companies to be "competitively cooperative" and bring about several piezoelectric innovations and inventions.

Types

Electromechanical

Early devices were based on an electromechanical system identical to an

electric bell An electric bell is a mechanical or electronic bell that functions by means of an electromagnet. When an electric current is applied, it produces a repetitive buzzing, clanging or ringing sound. Electromechanical bells have been widely used at r ...

without the metal gong. Similarly, a

relay A relay Electromechanical relay schematic showing a control coil, four pairs of normally open and one pair of normally closed contacts An automotive-style miniature relay with the dust cover taken off A relay is an electrically operated switc ...

may be connected to interrupt its own actuating

current Currents, Current or The Current may refer to: Science and technology * Current (fluid), the flow of a liquid or a gas ** Air current, a flow of air ** Ocean current, a current in the ocean *** Rip current, a kind of water current ** Current (hydr ...

, causing the

contact Contact may refer to: Interaction Physical interaction * Contact (geology), a common geological feature * Contact lens or contact, a lens placed on the eye * Contact sport, a sport in which players make contact with other players or objects * C ...

s to buzz (the contacts buzz at

line frequency The utility frequency, (power) line frequency (American English) or mains frequency (British English) is the nominal frequency of the oscillations of alternating current (AC) in a wide area synchronous grid transmitted from a power station to t ...

if powered by

alternating current Alternating current (AC) is an electric current that periodically reverses direction and changes its magnitude continuously with time, in contrast to direct current (DC), which flows only in one direction. Alternating current is the form in w ...

) 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

joy buzzer A joy buzzer (also called a hand buzzer) is a practical joke device that consists of a coiled mainspring inside a disc worn in the palm of the hand. When the wearer shakes hands with another person, a button on the disc releases the spring, whic ...

is an example of a purely mechanical buzzer and they require drivers. Other examples of them are doorbells.

Piezoelectric

element may be driven by an

oscillating Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...

electronic circuit or other

audio signal An audio signal is a representation of sound, typically using either a changing level of electrical voltage for analog signals or a series of binary numbers for Digital signal (signal processing), digital signals. Audio signals have frequencies i ...

source, driven with a

piezoelectric audio amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It is a two-port electronic circuit that uses electric power from a power supply ...

. Sounds commonly used to indicate that a button has been pressed are a click, a ring or a beep. Buzzer interior

A piezoelectric buzzer/beeper also depends on acoustic cavity resonance or

Helmholtz resonance Helmholtz resonance, also known as wind throb, refers to the phenomenon of air resonance in a cavity, an effect named after the German physicist Hermann von Helmholtz. This type of resonance occurs when air is forced in and out of a cavity (the r ...

to produce an audible beep.

Modern applications

While technological advancements have caused buzzers to be impractical and undesirable, there are still instances in which buzzers and similar circuits may be used. Present day applications include: * Novelty uses * Judging panels * Educational purposes *

Annunciator panel An annunciator panel, also known in some aircraft as the Centralized Warning Panel (CWP) or Caution Advisory Panel (CAP), is a group of lights used as a central indicator of status of equipment or systems in an aircraft, industrial process, buildin ...

s * Electronic

metronome A metronome () is a device that produces an audible click or other sound at a uniform interval that can be set by the user, typically in beats per minute (BPM). Metronomes may also include synchronized visual motion, such as a swinging pendulum ...

s *

Game show A game show (or gameshow) is a genre of broadcast viewing entertainment where contestants compete in a game for rewards. The shows are typically directed by a game show host, host, who explains the rules of the program as well as commentating a ...

lock-out device ''Jeopardy!'' is an American television game show created by Merv Griffin. The show is a quiz competition that reverses the traditional question-and-answer format of many quiz shows. Rather than being given questions, contestants are instead g ...

Microwave oven A microwave oven, or simply microwave, is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces Dipole#Molecular dipoles, polar molecules in the food to rotate and ...

s and other

household appliances A home appliance, also referred to as a domestic appliance, an electric appliance or a household appliance, is a machine which assists in household functions such as cooking, cleaning and food preservation. The domestic application attached to ...

Sport Sport is a physical activity or game, often Competition, competitive and organization, organized, that maintains or improves physical ability and skills. Sport may provide enjoyment to participants and entertainment to spectators. The numbe ...

ing events such as

basketball Basketball is a team sport in which two teams, most commonly of five players each, opposing one another on a rectangular Basketball court, court, compete with the primary objective of #Shooting, shooting a basketball (ball), basketball (appro ...

games * Electrical

alarms 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. Etymology The word ''alarm'' comes from the Old French ''a l'a ...

* Joy buzzer (mechanical buzzer used for pranks)

References

{{Authority control Electrical components Bells (percussion)

History

Electromechanical

Piezoelectric

Types

Electromechanical

Mechanical

Piezoelectric

Modern applications

See also

References