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Arc Converter
The arc converter, sometimes called the arc transmitter, or Poulsen arc after Danish engineer Valdemar Poulsen who invented it in 1903, was a variety of spark transmitter used in early wireless telegraphy. The arc converter used an electric arc to convert direct current electricity into radio frequency alternating current. It was used as a radio transmitter from 1903 until the 1920s when it was replaced by vacuum tube transmitters. One of the first transmitters that could generate continuous sinusoidal waves, it was one of the first technologies used to transmit sound (amplitude modulation) by radio. It is on the list of IEEE Milestones as a historic achievement in electrical engineering. History Elihu Thomson discovered that a carbon arc shunted with a series tuned circuit would "sing". This "singing arc" was probably limited to audio frequencies. Bureau of Standards credits William Duddell with the shunt resonant circuit around 1900. The English engineer William Duddell discov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poulsen Arc 1MW Transmitter
Poulsen is a Danish language, Danish patronymic surname meaning "son of Poul" (Danish version of Paul (name), Paul). The form Paulsen is a less common cognate. People with the name include: Sportspeople *Aage Poulsen (1919–1998), Danish long-distance runner *Anders Poulsen (ice hockey) (born 1991), Danish hockey player *Anders Poulsen (referee) (born 1981), Danish football referee *Andreas Poulsen (born 1999), Danish footballer *Annette Poulsen (born 1969), Danish swimmer *Christian Poulsen (born 1980), Danish professional football player *Christian Poulsen (chess player) (1912–1981), Danish chess master *Christian Poulsen (cyclist) (born 1979), Danish cyclist *Christopher Poulsen (born 1981), Danish footballer *Hanne Høegh Poulsen (born 1981), Danish taekwondo practitioner *Jakob Poulsen (born 1983), Danish professional football player *Jan B. Poulsen (born 1946), Danish football manager *Jonas Kældsø Poulsen (born 1985), Danish windsurfer *Kaj Poulsen (born 1942), Danish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resonant Circuit
An LC circuit, also called a resonant circuit, tank circuit, or tuned circuit, is an electric circuit consisting of an inductor, represented by the letter L, and a capacitor, represented by the letter C, connected together. The circuit can act as an electrical resonator, an electrical analogue of a tuning fork, storing energy oscillating at the circuit's resonant frequency. LC circuits are used either for generating signals at a particular frequency, or picking out a signal at a particular frequency from a more complex signal; this function is called a bandpass filter. They are key components in many electronic devices, particularly radio equipment, used in circuits such as oscillators, filters, tuners and frequency mixers. An LC circuit is an idealized model since it assumes there is no dissipation of energy due to resistance. Any practical implementation of an LC circuit will always include loss resulting from small but non-zero resistance within the components and connec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telegraphy
Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message. Thus flag semaphore is a method of telegraphy, whereas pigeon post is not. Ancient signalling systems, although sometimes quite extensive and sophisticated as in China, were generally not capable of transmitting arbitrary text messages. Possible messages were fixed and predetermined and such systems are thus not true telegraphs. The earliest true telegraph put into widespread use was the optical telegraph of Claude Chappe, invented in the late 18th century. The system was used extensively in France, and European nations occupied by France, during the Napoleonic era. The electric telegraph started to replace the optical telegraph in the mid-19th century. It was first taken up in Britain in the form of the Cooke and Wheatstone telegraph, initially used mostly as an aid to railway signalling. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia and it is located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. Comprising the westernmost peninsulas of Eurasia, it shares the continental landmass of Afro-Eurasia with both Africa and Asia. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south and Asia to the east. Europe is commonly considered to be Boundaries between the continents of Earth#Asia and Europe, separated from Asia by the drainage divide, watershed of the Ural Mountains, the Ural (river), Ural River, the Caspian Sea, the Greater Caucasus, the Black Sea and the waterways of the Turkish Straits. "Europe" (pp. 68–69); "Asia" (pp. 90–91): "A commonly accepted division between Asia and E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is also in free association with three Pacific Island sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Republic of Palau. It is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C. and its most populous city and principal financial center is New York City. Paleo-Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyril Frank Elwell
Cyril Frank Elwell (August 20, 1884 – 1963) was an Australian-bornHugh G.J. Aitken, ''The Continuous Wave: Technology and American Radio, 1900-1932'' Princeton University Press, 2014, Chapter 3 ''Elwell, Fuller and the Arc'' American inventor and pioneer in development of radio. He had an American father and a German mother, then went to Fort St. Model Public School in Sydney, Australia. Elwell arrived in the United States in 1902. He applied to Stanford University and entered the electrical engineering program there. In 1906, he organized fellow students to participate in repairs at the campus, owing to the San Francisco earthquake. He graduated in 1907. He founded the Poulsen Wireless Telephone and Telegraph Company, later renamed Federal Telegraph Company in 1909. Elwell designed a large transformer for electric arc furnace reduction of iron ore; this became the topic of his thesis. He had published some technical papers on applications in electric metallurgy. In 1908 he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peder Oluf Pedersen
Peder Oluf Pedersen (19 June 1874 – 30 August 1941) was a Danish engineer and physicist. He is notable for his work on electrotechnology and his cooperation with Valdemar Poulsen on the developmental work on Wire recorders, which he called a telegraphone, and the arc converter known as the Poulsen Arc Transmitter. Pedersen became a professor of telegraphy, telephony and radio in 1912.Biography from the History Center retrieved 2011 Sept 28 He became principal of the College of Advanced Technology (''Den Poly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Britain
Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is dominated by a maritime climate with narrow temperature differences between seasons. The 60% smaller island of Ireland is to the west—these islands, along with over 1,000 smaller surrounding islands and named substantial rocks, form the British Isles archipelago. Connected to mainland Europe until 9,000 years ago by a landbridge now known as Doggerland, Great Britain has been inhabited by modern humans for around 30,000 years. In 2011, it had a population of about , making it the world's third-most-populous island after Java in Indonesia and Honshu in Japan. The term "Great Britain" is often used to refer to England, Scotland and Wales, including their component adjoining islands. Great Britain and Northern Ireland now constitute the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Germany
Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated between the Baltic and North seas to the north, and the Alps to the south; it covers an area of , with a population of almost 84 million within its 16 constituent states. Germany borders Denmark to the north, Poland and the Czech Republic to the east, Austria and Switzerland to the south, and France, Luxembourg, Belgium, and the Netherlands to the west. The nation's capital and most populous city is Berlin and its financial centre is Frankfurt; the largest urban area is the Ruhr. Various Germanic tribes have inhabited the northern parts of modern Germany since classical antiquity. A region named Germania was documented before AD 100. In 962, the Kingdom of Germany formed the bulk of the Holy Roman Empire. During the 16th ce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Technology
Technology is the application of knowledge to reach practical goals in a specifiable and reproducible way. The word ''technology'' may also mean the product of such an endeavor. The use of technology is widely prevalent in medicine, science, industry, communication, transportation, and daily life. Technologies include physical objects like utensils or machines and intangible tools such as software. Many technological advancements have led to societal changes. The earliest known technology is the stone tool, used in the prehistoric era, followed by fire use, which contributed to the growth of the human brain and the development of language in the Ice Age. The invention of the wheel in the Bronze Age enabled wider travel and the creation of more complex machines. Recent technological developments, including the printing press, the telephone, and the Internet have lowered communication barriers and ushered in the knowledge economy. While technology contributes to econom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hertz
The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one hertz is the reciprocal of one second. It is named after Heinrich Rudolf Hertz (1857–1894), the first person to provide conclusive proof of the existence of electromagnetic waves. Hertz are commonly expressed in multiples: kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz). Some of the unit's most common uses are in the description of periodic waveforms and musical tones, particularly those used in radio- and audio-related applications. It is also used to describe the clock speeds at which computers and other electronics are driven. The units are sometimes also used as a representation of the energy of a photon, via the Planck relation ''E'' = ''hν'', where ''E'' is the photon's energy, ''ν'' is its freq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency
Frequency is the number of occurrences of a repeating event per unit of time. It is also occasionally referred to as ''temporal frequency'' for clarity, and is distinct from ''angular frequency''. Frequency is measured in hertz (Hz) which is equal to one event per second. The period is the interval of time between events, so the period is the reciprocal of the frequency. For example, if a heart beats at a frequency of 120 times a minute (2 hertz), the period, —the interval at which the beats repeat—is half a second (60 seconds divided by 120 beats). Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals (sound), radio waves, and light. Definitions and units For cyclical phenomena such as oscillations, waves, or for examples of simple harmonic motion, the term ''frequency'' is defined as the number of cycles or vibrations per unit of time. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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