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Alarm
An alarm device is a mechanism that gives an audible, visual or other kind of alarm signal to alert someone to a problem or condition that requires urgent attention. Alphabetical musical instruments Etymology The word ''alarm'' comes from the Old French ''a l'arme'' meaning "to the arms", or "to the weapons", telling armed men to pick up their weapons and get ready for action because an enemy may have suddenly appeared. The word ''alarum'' is an archaic form of ''alarm''. It was sometimes used as a call to arms in the stage directions of Elizabethan dramas. The term comes from the Italian ''all'armi'' and appears 89 times in Shakespeare's first folio. Often explained as the off-stage sounds of conflict or disturbance, recent research suggests a bell or drum may have been used to rouse soldiers from sleep. History and development Early alarm devices were often bells, drums, other musical instruments, or any items which made unusual loud noises that attracted the attention o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smoke Detector
A smoke detector is a device that senses smoke, typically as an indicator of fire. Smoke detectors are usually housed in plastic enclosures, typically shaped like a disk about in diameter and thick, but shape and size vary. Smoke can be detected either optically (photoelectric) or by physical process (ionization). Detectors may use one or both sensing methods. Sensitive alarms can be used to detect and deter smoking in banned areas. Smoke detectors in large commercial and industrial buildings are usually connected to a central fire alarm system. Household smoke detectors, also known as ''smoke alarms'', generally issue an audible or visual alarm from the detector itself or several detectors if there are multiple devices interlinked. Household smoke detectors range from individual battery-powered units to several interlinked units with battery backup. With interlinked units, if any unit detects smoke, alarms will trigger at all of the units. This happens even if household power ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burglar Alarm
A security alarm is a system designed to detect intrusion, such as unauthorized entry, into a building or other areas such as a home or school. Security alarms used in residential, commercial, industrial, and military properties protect against burglary (theft) or property damage, as well as personal protection against intruders. Security alerts in neighborhoods show a connection with diminished robbery. Car alarms likewise help protect vehicles and their contents. Prisons also use security systems for the control of inmates. Some alarm systems serve a single purpose of burglary protection; combination systems provide fire and intrusion protection. Intrusion-alarm systems are combined with closed-circuit television surveillance (CCTV) systems to record intruders' activities and interface to access control systems for electrically locked doors. There are many types of security systems. Homeowners typically have small, self-contained noisemakers. These devices can also be complica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alarm Signal
In animal communication, an alarm signal is an antipredator adaptation in the form of signals emitted by social animals in response to danger. Many primates and birds have elaborate alarm calls for warning conspecifics of approaching predators. For example, the alarm call of the blackbird is a familiar sound in many gardens. Other animals, like fish and insects, may use non-auditory signals, such as chemical messages. Visual signs such as the white tail flashes of many deer have been suggested as alarm signals; they are less likely to be received by conspecifics, so have tended to be treated as a signal to the predator instead. Different calls may be used for predators on the ground or from the air. Often, the animals can tell which member of the group is making the call, so that they can disregard those of little reliability. Evidently, alarm signals promote survival by allowing the receivers of the alarm to escape from the source of peril; this can evolve by kin selection, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alarm Clock
An alarm clock (or sometimes just an alarm) is a clock that is designed to alert an individual or group of individuals at a specified time. The primary function of these clocks is to awaken people from their night's sleep or short naps; they are sometimes used for other reminders as well. Most use sound; some use light or vibration. Some have sensors to identify when a person is in a light stage of sleep, in order to avoid waking someone who is deeply asleep, which causes tiredness, even if the person has had adequate sleep. To turn off the sound or light, a button or handle on the clock is pressed; most clocks automatically turn off the alarm if left unattended long enough. A classic analog alarm clock has an extra hand or inset dial that is used to specify the time at which the alarm will ring. Alarm clocks are also used in mobile phones, watches, and computers. Many alarm clocks have radio receivers that can be set to start playing at specified times, and are known as ''clo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Civil Defense Siren
A civil defense siren, also known as an air-raid siren or tornado siren, is a siren used to provide an emergency population warning to the general population of approaching danger. It is sometimes sounded again to indicate the danger has passed. Some sirens, especially within small towns, are also used to call the volunteer fire department when needed. Initially designed to warn city dwellers of air raids in World War II, they were later used to warn of nuclear attack and natural destructive weather patterns, such as tornadoes. The generalized nature of sirens led to many of them being replaced with more specific warnings, such as the broadcast-based Emergency Alert System and the Cell Broadcast-based Wireless Emergency Alerts and EU-Alert mobile technologies. A mechanical siren generates sound by spinning a slotted chopper wheel to interrupt a stream of air at a regular rate. Modern sirens can develop a sound level of up to 135 decibels at . The Chrysler air raid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fire Alarm Notification Appliance
A fire alarm notification appliance is an active fire protection component of a fire alarm system. A notification appliance may use audible, visible, or other stimuli to alert the occupants of a fire or other emergency condition requiring action. Audible appliances have been in use longer than any other method of notification. Initially, all appliances were either electromechanical horns or electric bells, which would later be replaced by electronic sounders. Most of today's appliances produce sound pressure levels between 45 and 120 decibels at ten feet. Methods of notification The primary function of the notification appliance is to alert persons at risk. Several methods are used and documented in industry specifications published by UL. Alerting methods include: * Sound (audible signals) ** ~3 kHz / ~3100 Hz tone (high frequency). Used in many current notification devices. ** 520 Hz (low frequency). Used in newer notification devices. ** 45 dB to 120&nb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fire Alarm System
A fire alarm system warns people when smoke, fire, carbon monoxide or other fire-related or general notification emergency, emergencies are detected. These alarms may be activated automatically from smoke detectors and heat detectors or may also be activated via manual fire alarm activation devices such as manual call points or pull stations. Alarms can be either motorized bells or wall mountable sounders or horns. They can also be speaker strobes which sound an alarm, followed by a voice evacuation message which warns people inside the building not to use the elevators. Fire alarm sounders can be set to certain frequencies and different tones including low, medium, and high, depending on the country and manufacturer of the device. Most fire alarm systems in Europe sound like a siren with alternating frequencies. Fire alarm electronic devices are known as horns in the United States and Canada and can be either continuous or set to different codes. Fire alarm warning devices can al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fire Alarm System
A fire alarm system warns people when smoke, fire, carbon monoxide or other fire-related or general notification emergency, emergencies are detected. These alarms may be activated automatically from smoke detectors and heat detectors or may also be activated via manual fire alarm activation devices such as manual call points or pull stations. Alarms can be either motorized bells or wall mountable sounders or horns. They can also be speaker strobes which sound an alarm, followed by a voice evacuation message which warns people inside the building not to use the elevators. Fire alarm sounders can be set to certain frequencies and different tones including low, medium, and high, depending on the country and manufacturer of the device. Most fire alarm systems in Europe sound like a siren with alternating frequencies. Fire alarm electronic devices are known as horns in the United States and Canada and can be either continuous or set to different codes. Fire alarm warning devices can al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siren (alarm)
A siren is a loud noise-making device. Civil defense sirens are mounted in fixed locations and used to warn of natural disasters or attacks. Sirens are used on emergency service vehicles such as ambulances, police cars, and fire engines. There are two general types: mechanical and electronic. Many fire sirens (used for calling the volunteer fire fighters) serve double duty as tornado or civil defense sirens, alerting an entire community of impending danger. Most fire sirens are either mounted on the roof of a fire station or on a pole next to the fire station. Fire sirens can also be mounted on or near government buildings, on tall structures such as water towers, as well as in systems where several sirens are distributed around a town for better sound coverage. Most fire sirens are single tone and mechanically driven by electric motors with a rotor attached to the shaft. Some newer sirens are electronically driven speakers. Fire sirens are often called "fire whistles", "fir ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buzzer
A buzzer or beeper is an audio signaling device, which may be mechanical, electromechanical, or piezoelectric (''piezo'' for short). Typical uses of buzzers and beepers include alarm devices, timers, train and confirmation of user input such as a mouse click or keystroke. History Electromechanical The electric buzzer was invented in 1831 by Joseph Henry. They were mainly used in early doorbells 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Klaxon
A horn is a sound-making device that can be equipped to motor vehicles, buses, bicycles, trains, trams (otherwise known as streetcars in North America), and other types of vehicles. The sound made usually resembles a "honk" (older vehicles) or a "beep" (modern vehicles). The driver uses the horn to warn others of the vehicle's approach or presence, or to call attention to some hazard. Motor vehicles, ships and trains are required by law in some countries to have horns. Like trams, trolley cars and streetcars, bicycles are also legally required to have an audible warning device in many areas, but not universally, and not always a horn. Types Bicycle Bicycles sometimes have a classic ''bulb horn'', operated by squeezing a rubber bulb attached to a metal horn. Squeezing the bulb forces air through a steel Reed (instrument), reed located in the throat of the horn, making it vibrate, producing a single note. The flaring horn matches the acoustic impedance of the reed to the open air ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Steam Whistle
A steam whistle is a device used to produce sound in the form of a whistle using live steam, which creates, projects, and amplifies its sound by acting as a vibrating system (compare to train horn). Operation The whistle consists of the following main parts, as seen on the drawing: the whistle bell (1), the steam orifice or aperture (2), and the valve (9). When the lever (10) is actuated (usually via a pull cord), the valve opens and lets the steam escape through the orifice. The steam will alternately compress and rarefy in the bell, creating the sound. The pitch, or tone, is dependent on the length of the bell; and also how far the operator has opened the valve. Some locomotive engineers invented their own distinctive style of whistling. Uses of steam whistles Steam whistles were often used in factories, and similar places to signal the start or end of a shift, etc. steam-powered railway locomotives, traction engines, and steam ships have traditionally been fitted wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
