Traditional wind-up (keywound), mechanical, spring-driven alarm clock An alarm clock (or sometimes just an alarm) is a that is designed to alert an individual or group of individuals at 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 stop the sound or light, a button or handle on the clock is pressed; most clocks automatically stop the alarm if left unattended long enough. A classic alarm clock has an extra or inset dial that is used to specify the time at which to activate the alarm.
Alarm clocks are also found on and. Traditional mechanical alarm clocks have one or two that ring by means of a that powers a gear to propel a hammer back and forth between the two bells or between the interior sides of a single bell. In some models, the back encasement of the clock itself acts as the bell. In an electric bell-style alarm clock, the bell is rung by an and that turns the circuit on and off repeatedly. Alarm clocks can make other noises. Simple -powered alarm clocks make a loud buzzing or beeping sound to wake a sleeper, while novelty alarm clocks can speak, laugh, sing, or play sounds from nature.
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Some alarm clocks have that can be set to start playing at specified times, and are known as clock radios. Some alarm clocks can set multiple alarms, a useful feature for couples who have different waking up schedules. A progressive alarm clock, still new in the market, can have different alarms for different times (see ) and even play music of your choice. Most modern televisions, mobile phones and digital watches have alarm clock functions to turn on or make sounds at a specific time. The, detail of the pedestal: offers laurels of victory; we can see the of, in the lower right-hand corner. The philosopher (428–348 BC) was said to possess a large with an unspecified alarm signal similar to the sound of a; he used it at night, possibly for signaling the beginning of his lectures at dawn ( 4.174c).
The engineer and inventor ( 285–222 BC) fitted his with dial and pointer for indicating the time, and added elaborate 'alarm systems, which could be made to drop pebbles on a gong, or blow trumpets (by forcing bell-jars down into water and taking the compressed air through a beating reed) at pre-set times' ( 11.11). The senator (c. 485–585) advocated in his rulebook for monastic life the water clock as a useful alarm for the 'soldiers of ' (Cassiod. The Christian rhetorician described in detail prior to 529 a complex public in his home town which featured an hourly gong and figures moving mechanically day and night. In China, a was devised by the and inventor (683–727). The Chinese engineers and integrated striking clock mechanisms in astronomical clocks in the 10th and 11th centuries, respectively.
A striking clock outside of China was the water-powered clock tower near the in,, which struck once every hour. It was constructed by the al-Kaysarani in 1154.
In 1235, an early monumental water-powered alarm clock that 'announced the appointed and the time both by day and by night' was completed in the entrance hall of the in. From the 14th century, some clock towers in were also capable of chiming at a fixed time every day; the earliest of these was described by the writer in 1319. The most famous original striking clock tower still standing is possibly the one in in,. The was assembled in 1493, by the famous clockmaker Gian Carlo Rainieri from, where his father Gian Paolo Rainieri had already constructed another famous device in 1481. In 1497, Simone Campanato moulded the great bell (h. 1,56 m., diameter m.
1,27), which was put on the top of the tower where it was alternatively beaten by the Due Mori ( Two ), two bronze statues (h. 2,60) handling a hammer. User-settable mechanical alarm clocks date back at least to 15th-century Europe. These early alarm clocks had a ring of holes in the clock dial and were set by placing a pin in the appropriate hole. Another mechanical alarm clock was created by Levi Hutchins, of in the, in 1787.
This device he made only for himself however, and it only rang at 4 AM, in order to wake him for his job. The French inventor Antoine Redier was the first to patent an adjustable mechanical alarm clock, in 1847. [ ] Alarm clocks, like almost all other consumer goods in the United States, ceased production in the spring of 1942, as the factories which made them were converted over to war work during, but they were one of the first consumer items to resume manufacture for civilian use, in November 1944. By that time, a critical shortage of alarm clocks had developed due to older clocks wearing out or breaking down. Workers were late for, or missed completely, their scheduled shifts in jobs critical to the war effort. In a pooling arrangement overseen by the, several clock companies were allowed to start producing new clocks, some of which were continuations of pre-war designs, and some of which were new designs, thus becoming among the first 'postwar' consumer goods to be made, before the war had even ended. The price of these 'emergency' clocks was, however, still strictly regulated by the Office of Price Administration.
[ ] The first radio alarm clock was invented by James F. Reynolds, in the 1940s and another design was also invented by Paul L. [ ] Clock radio [ ]. 'Clock radio' redirects here. For the clocks synchronised by radio signals, see. A clock radio is an alarm clock and integrated in one device. The clock may turn on the radio at a designated time to wake the user, and may also include a buzzer.
Typically, they are placed on the bedside stand. Some models offer dual alarm and 'snooze', a large button on the top that stops the alarm and sets it to ring again a few minutes later. Some clock radios also have a 'sleep' timer, which turns the music from radio on for a set amount of time (usually around one hour).
This is useful for people who like to fall asleep with the radio on. In addition to, recent clock radios have other music sources such as,, and/or audio CD. When the alarm is triggered, it can play a set radio station or the music from a selected music source to awaken the sleeper. These models usually come with a dock for iPod/iPhone that also charges the device while it is docked.
They can play FM/AM radio, iPod/iPhone or CD like a typical music player as well (without being triggered by the alarm function). A few popular models offer 'nature sounds' like rain, forest, fire, sea, waterfall etc., in place of the buzzer. Clock radios are powered by AC power from the wall socket.
In the event of a power interruption, older electronic digital models used to reset the time to midnight (00:00) and lose alarm settings. This would cause failure to trigger the alarm even if the power is restored. To solve this issue, they trigger the alarm at 00:01 after a reset, so that at least the user is able to correct the clock and alarm settings. Most of the recent clock radios use a battery backup to maintain the time and alarm settings.
Some advanced (not to be confused with clocks with AM/FM ) have a feature which sets the time automatically using signals from -synced such as, making the clock accurate and immune to time reset due to power interruptions. Image gallery [ ] •. An alarm clock as the emblem of the in. Other alarm signals [ ] The deaf and hard of hearing are often unable to perceive auditory alarms when asleep. They may use specialized alarms, including alarms with flashing lights instead of or in addition to noise. Alarms which can connect to vibrating devices (small ones inserted into pillows, or larger ones placed under bedposts to shake the bed) also exist.
[ ] Computer alarms [ ] Alarm clock software programs have been developed for. A computer acting as an alarm clock may allow a virtually unlimited number of alarm times (i.e. ) and personalized tones.
[ ] Online alarm clocks are also available through the use of different websites, e.g.. Mobile phone alarms [ ] Many modern feature built-in alarm clocks that do not need the phone to be switched on for the alarm to ring off.
[ ] Some of these mobile phones feature the ability for the user to set the alarm's, and in some cases music can be to the phone and then chosen to play for waking. [ ] Next-generation alarms [ ]. Sleeptracker, an alarm clock which tracks sleep phases Scientific studies on sleep having shown that at awakening is an important factor in amplifying. Alarm clocks involving sleep stage monitoring appeared on the market in 2005.
Using sensing technologies such as electrodes or, these alarm clocks are supposed to wake people only from light sleep. [ ] are another technology meant to mediate these effects. Sleepers can become accustomed to the sound of their alarm clock if it has been used for a period of time, making it less effective.
[ ] Because progressive alarm clocks have a complex waking procedure, they can deter this adaptation due to the body needing to adapt to more stimuli than just a simple sound alert. [ ] Time switches used as alarms [ ]. •, p. 522;, p. 363 •, p. 35 • ^ Dohrn-van Rossum, Gerhard, 'Clocks',, edited by: Hubert Cancik and Helmuth Schneider, 2009 •, Volume 4, Part 2, pp. 473–5 •, Volume 4, Part 2, p. 165 • (1991), 'Arabic Mechanical Engineering: Survey of the Historical Sources',,, 1: 167–186 [180],: •, Volume 4, Part 2, p. 249, The Grove encyclopedia of decorative arts, Gordon Campbell, vol.
1, Oxford University Press, 2006,. • 21 November 2008 at the., entry, Clock Dictionary.
• Mary Bellis.. Retrieved 2 November 2006. • (26 November 1999)... From the original on 31 December 2006. Retrieved 7 January 2007.
• Reuven Fenton (29 August 2007).. Retrieved 9 June 2008. Sources [ ] • Humphrey, John William;; Sherwood, Andrew N. (2003), Greek and Roman Technology: A Sourcebook.
Annotated Translations of Greek and Latin Texts and Documents, Taylor & Francis Routledge, • Landels, John G. (1979), 'Water-Clocks and Time Measurement in Classical Antiquity', Endeavour, 3 (1), pp. 32–37,: • Lewis, Michael (2000), 'Theoretical Hydraulics, Automata, and Water Clocks', in, Handbook of Ancient Water Technology, Technology and Change in History, 2, Leiden: Brill, pp. 343–369, External links [ ] • Media related to at Wikimedia Commons.