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Entry Phone
An intercom, also called an intercommunication device, intercommunicator, or interphone, is a stand-alone voice communications system for use within a building or small collection of buildings which functions independently of the public telephone network. Intercoms are generally mounted permanently in buildings and vehicles. Intercoms can incorporate connections to public address loudspeaker systems, walkie talkies, telephones, and other intercom systems. Some intercom systems incorporate control of devices such as signal lights and door latches. Intercoms are used on a wide variety of properties; from houses that only require one connection between a resident and the property's entrance to multi-unit apartments that require intercom hardware to be installed in every individual apartment. Some are equipped with video and its wiring (electrical installation) can be connected to the outside with a few pairs (4-6 pairs) while controlling an electric strike. The latest generations a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell Telephone Magazine (1922) (14569859438)
A bell is a directly struck idiophone percussion instrument. Most bells have the shape of a hollow cup that when struck vibrates in a single strong strike tone, with its sides forming an efficient resonator. The strike may be made by an internal "clapper" or "uvula", an external hammer, or—in small bells—by a small loose sphere enclosed within the body of the bell (jingle bell). Bells are usually cast from bell metal (a type of bronze) for its resonant properties, but can also be made from other hard materials. This depends on the function. Some small bells such as ornamental bells or cowbells can be made from cast or pressed metal, glass or ceramic, but large bells such as a church, clock and tower bells are normally cast from bell metal. Bells intended to be heard over a wide area can range from a single bell hung in a turret or bell-gable, to a musical ensemble such as an English ring of bells, a carillon or a Russian zvon which are tuned to a common scale and installe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Performing Arts Center
Performing arts center/centre (see spelling differences), often abbreviated as PAC, is used to refer to: * A multi-use performance space that is intended for use by various types of the performing arts, including dance, music and theatre. :The intended multiple use of performing arts centers in this sense differentiates them from single-purpose concert halls, opera houses or theatres, although the actual use of single-purpose spaces for other than their intended use is widespread. This sort of space has a long history extending to the Roman Colosseum and Greek amphitheatres. * A cluster of performance spaces, either separate buildings or under one roof, each space designed for a specific purpose such as symphonic music or chamber music or theatre, but multi-purpose as a whole. The modern version of this came into being only in the 1960s. :Examples of this type of PAC are the Kennedy Center in Washington, D.C., the Sydney Opera House, and the Lincoln Center in New York City. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct Current
Direct current (DC) is one-directional flow of electric charge. An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even through a vacuum as in electron or ion beams. The electric current flows in a constant direction, distinguishing it from alternating current (AC). A term formerly used for this type of current was galvanic current. The abbreviations ''AC'' and ''DC'' are often used to mean simply ''alternating'' and ''direct'', as when they modify ''current'' or ''voltage''. Direct current may be converted from an alternating current supply by use of a rectifier, which contains electronic elements (usually) or electromechanical elements (historically) that allow current to flow only in one direction. Direct current may be converted into alternating current via an inverter. Direct current has many uses, from the charging of batteries to large power sup ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volt
The volt (symbol: V) is the unit of electric potential, electric potential difference (voltage), and electromotive force in the International System of Units (SI). It is named after the Italian physicist Alessandro Volta (1745–1827). Definition One volt is defined as the electric potential between two points of a conducting wire when an electric current of one ampere dissipates one watt of power between those points. Equivalently, it is the potential difference between two points that will impart one joule of energy per coulomb of charge that passes through it. It can be expressed in terms of SI base units ( m, kg, second, s, and ampere, A) as : \text = \frac = \frac = \frac. It can also be expressed as amperes times ohms (current times resistance, Ohm's law), webers per second (magnetic flux per time), watts per ampere (power per current), or joules per coulomb (energy per charge), which is also equivalent to electronvolts per elementary charge: : \text = \tex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Headphones
Headphones are a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound. Headphones let a single user listen to an audio source privately, in contrast to a loudspeaker, which emits sound into the open air for anyone nearby to hear. Headphones are also known as earspeakers, earphones or, colloquially, cans. Circumaural ('around the ear') and supra-aural ('over the ear') headphones use a band over the top of the head to hold the speakers in place. Another type, known as earbuds or earpieces consist of individual units that plug into the user's ear canal. A third type are bone conduction headphones, which typically wrap around the back of the head and rest in front of the ear canal, leaving the ear canal open. In the context of telecommunication, a headset is a combination of headphone and microphone. Headphones connect to a signal source such as an audio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earpiece
In-ear monitors (IEMs) are devices used by musicians, audio engineers and audiophiles to listen to music or to hear a personal mix of vocals and stage instrumentation for live performance or recording studio mixing. They are also used by television presenters in order to receive vocal instructions, info, and breaking news announcements from a producer that only the presenter hears. They are often custom fitted for an individual's ears to provide comfort and a high level of noise reduction from ambient surroundings. Their origins as a tool in live music performance can be traced back to the mid-1980s. A stage monitor system is any system that provides a mix of audio sources to a performer on stage. Traditionally, loudspeakers were placed on the stage directed toward the performers. These loudspeakers can have disadvantages. First, floor wedges greatly increase the onstage volume, in some cases to potential hearing damage levels. Second, while floor wedges can be placed in front ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interruptible Feedback
Interruptible foldback (IFB), also known as interrupted foldback, interruptible feedback, or interrupt for broadcast, is a monitoring and cueing system used in television, filmmaking, video production, and radio broadcast for one-way communication from the director or assistant director to on-air talent or a remote location. The names are backronyms for the Telex IFB-XXX model line. Less common names for the system include program cue interrupt (PCI) and switched talkback. IFB is often facilitated using an earpiece that on-air persons wear to get cues, feedback or direction from their control rooms. The earpiece itself may also be referred to as an IFB. Sometimes IFB is accomplished by the director talking to off-camera personnel who visually cue the on-camera talent. The IFB is a special intercom circuit that consists of a mix-minus program feed sent to an earpiece worn by talent via a wire, telephone, or radio receiver (audio that is being "fed back" to talent) that can be inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Party Line (telephony)
A party line (multiparty line, shared service line, party wire) is a local loop telephone circuit that is shared by multiple telephone service subscribers. Party line systems were widely used to provide telephone service, starting with the first commercial switchboards in 1878. A majority of Bell System subscribers in the mid-20th century in the United States and Canada were served by party lines, which had a discount over individual service. During wartime shortages, these were often the only available lines. British users similarly benefited from the party line discount. Farmers in rural Australia and South Africa used party lines, where a single line spanned miles from the nearest town to one property and on to the next. History Telephone companies offered party lines beginning in the late 1800s, although subscribers in all but the most rural areas may have had the option to upgrade to individual line service at an additional monthly charge. The service was common in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pittock Mansion Intercom
Pittock may refer to: * Pittock Block, a building in downtown Portland, Oregon, U.S. * Pittock Dam, a dam in Woodstock, Ontario, Canada * Pittock House, a house in Camas, Washington, U.S. * Pittock Mansion, a French Renaissance-style "château" in Portland, Oregon, U.S. * Markle-Pittock House, a house in southwest Portland, Oregon, U.S. People with the surname * Amelia Pittock (born 1983), professional Australian squash player * Georgiana Burton Pittock (1845–1918), pioneer and community leader in Portland, Oregon, U.S. * Gordon Pittock (1909–1983), Canadian politician * Henry Pittock (1835–1919), American pioneer, newspaper editor, publisher, and wood and paper magnate * Murray Pittock Murray G. H. Pittock MAE FRSE (born 5 January 1962) is a Scottish historian, Bradley Professor of Literature at the University of Glasgow and Pro Vice Principal at the University, where he has served in senior roles including Dean and Vice Princip ... (born 1962), Scottish historian See ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emergency Medical Technician
An emergency medical technician (EMT), also known as an ambulance technician, is a health professional that provides emergency medical services. EMTs are most commonly found working in ambulances. In English-speaking countries, paramedics are a separate profession that has additional educational requirements, qualifications, and scope of practice. EMTs are often employed by private ambulance services, municipal EMS agencies, governments, hospitals, and fire departments. Some EMTs are paid employees, while others (particularly those in rural areas) are volunteers. EMTs provide medical care under a set of protocols, which are typically written by a physician. Hazard controls EMTs are exposed to a variety of hazards such as lifting patients and equipment, treating those with infectious disease, handling hazardous substances, and transportation via ground or air vehicles. Employers can prevent occupational illness or injury by providing safe patient handling equipment, impleme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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