Instruct: Given a question, retrieve relevant documents that can help answer the question.
Query: When was Lee de Forest born?
Lee de Forest (August 26, 1873 – June 30, 1961) was an American inventor, self-described "Father of Radio", and a pioneer in the development of sound-on-film recording used for motion pictures. He had over 180 patents, but also a tumultuous career—he boasted that he made, then lost, four fortunes. He was also involved in several major patent lawsuits, spent a substantial part of his income on legal bills, and was even tried (and acquitted) for mail fraud. His most famous invention, in 1906, was the three-element "Audion" (triode) vacuum tube, the first practical amplification device. Although De Forest had only a limited understanding of how it worked, it was the foundation of the field of electronics, making possible radio broadcasting, long distance telephone lines, and talking motion pictures, among countless other applications.
De Forest's Audion did not see much use until its ability to amplify was recognized around 1912 by several researchers, who used it to build the first successful amplifying radio receivers and electronic oscillators. The many uses for amplification motivated its rapid development. By 1913 improved versions with higher vacuum were developed by Harold Arnold at American Telephone and Telegraph Company, which had purchased the rights to the Audion from De Forest, and Irving Langmuir at General Electric, who named his tube the "Pliotron", These were the first vacuum tube triodes. The name "triode" appeared later, when it became necessary to distinguish it from other kinds of vacuum tubes with more or fewer elements (e.g. diodes, tetrodes, pentodes, etc.). There were lengthy lawsuits between De Forest and von Lieben, and De Forest and the Marconi Company, who represented John Ambrose Fleming, the inventor of the diode.
U.S. patent law included a provision for challenging grants if another inventor could prove prior discovery. With an eye to increasing the value of the patent portfolio that would be sold to Western Electric in 1917, beginning in 1915 de Forest filed a series of patent applications that largely copied Armstrong's claims, in the hopes of having the priority of the competing applications upheld by an interference hearing at the patent office. Based on a notebook entry recorded at the time, de Forest asserted that, while working on the cascade amplifier, he had stumbled on August 6, 1912 across the feedback principle, which was then used in the spring of 1913 to operate a low-powered transmitter for heterodyne reception of Federal Telegraph arc transmissions. However, there was also strong evidence that de Forest was unaware of the full significance of this discovery, as shown by his lack of follow-up and continuing misunderstanding of the physics involved. In particular, it appeared that he was unaware of the potential for further development until he became familiar with Armstrong's research. De Forest was not alone in the interference determination — the patent office identified four competing claimants for its hearings, consisting of Armstrong, de Forest, General Electric's Langmuir, and a German, Alexander Meissner, whose application would be seized by the Office of Alien Property Custodian during World War I.
The audio amplifier was invented around 1912 by Lee De Forest, made possible by his invention of the first practical amplifying electrical component, the triode vacuum tube (or "valve" in British English) in 1907. The triode was a three terminal device with a control grid that can modulate the flow of electrons from the filament to the plate. The triode vacuum amplifier was used to make the first AM radio. Early audio power amplifiers were based on vacuum tubes and some of these achieved notably high audio quality (e.g., the Williamson amplifier of 1947-9). Audio power amplifiers based on transistors became practical with the wide availability of inexpensive transistors in the late 1960s. Since the 1970s, most modern audio amplifiers are based on solid state devices (transistors such as BJTs, FETs and MOSFETs). Transistor-based amplifiers are lighter in weight, more reliable and require less maintenance than tube amplifiers. In the 2010s, there are still audio enthusiasts, musicians (particularly electric guitarists, electric bassists, Hammond organ players and Fender Rhodes electric piano players, among others), audio engineers and music producers who prefer tube-based amplifiers, and what is perceived as a "warmer" tube sound.
Key design parameters for audio power amplifiers are frequency response, gain, noise, and distortion. These are interdependent; increasing gain often leads to undesirable increases in noise and distortion. While negative feedback actually reduces the gain, it also reduces distortion. Most audio amplifiers are linear amplifiers operating in class AB.
François Leleux (born July 1971 in Croix, Nord) is a French oboist, conductor, and professor. His professional career began at 18 when he became principal oboe at the Paris Opera. He went on to win a solo position at the Bavarian Radio Symphony Orchestra and currently does some concerts with the Chamber Orchestra of Europe as well as putting out CDs. He is married to violinist Lisa Batiashvili.
She was named in honor of Reginald Aubrey Fessenden, born in Brome County, Quebec, Canada, 6 October 1866. He served as head chemist with Thomas Edison's East Orange, New Jersey, laboratories. In 1890 he began concentrating on electrical engineering, and through the next years made many important inventions and improvements in existing devices. His great contributions in the field of radio (particularly the invention of radio-telephony were of marked benefit not only to the Navy but to all seamen. He died 22 July 1932, at his home on Bermuda.
The development of thermionic valves starting around 1902, provided an entirely electronic method of amplifying signals. The first practical version of such devices was the Audion triode, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. Since the only previous device which was widely used to strengthen a signal was the relay used in telegraph systems, the amplifying vacuum tube was first called an "electron relay". The terms "amplifier" and "amplification", derived from the Latin "amplificare", ("to enlarge or expand"), were first used for this new capability around 1915 when triodes became widespread.
In 1857, Édouard-Léon Scott de Martinville invented the phonautograph, the first device that could record sound waves as they passed through the air. It was intended only for visual study of the recording and could not play back the sound. The recording medium was a sheet of soot-coated paper wrapped around a rotating cylinder carried on a threaded rod. A stylus, attached to a diaphragm through a series of levers, traced a line through the soot, creating a graphic record of the motions of the diaphragm as it was minutely propelled back and forth by the audio-frequency variations in air pressure.
Leake was born on Rocky Spring Plantation in Goochland County, Virginia in 1813. He graduated from the Hampden-Sydney College with a Bachelor of Arts degree in 1832, from University of Virginia in 1833, and from the College of William and Mary with a Bachelor of Laws in 1836.
Reginald A. Fessenden was born Quebec in 1866, and entered Bishop's University as a precocious young mathematical prodigy, but left in 1884 without graduating. In 1886, he took a position at the Edison Machine Works, working for inventor Thomas Edison. During an academic period teaching at Purdue University and at the University of Pittsburgh, Fessenden engaged in research on the nascent subject of wireless telegraphy. Much of the rest of his life he was employed in industry, either directly or as a consultant, but was often living near poverty, and produced a stream of inventions. In 1904 he invented the rotary spark-gap transmitter, and in 1906 he built a large transmitter in Massachusetts from which he successfully made a voice transmission. He also discovered the means to recombine separate frequencies to form a coherent audible sound. At his death he was described by inventor and businessman Elihu Thomson as "the greatest wireless inventor of the age, greater than Marconi."
An amplifier can either be a separate piece of equipment or an electrical circuit contained within another device. Amplification is fundamental to modern electronics, and amplifiers are widely used in almost all electronic equipment. Amplifiers can be categorized in different ways. One is by the frequency of the electronic signal being amplified. For example, audio amplifiers amplify signals in the audio (sound) range of less than 20 kHz, RF amplifiers amplify frequencies in the radio frequency range between 20 kHz and 300 GHz, and servo amplifiers and instrumentation amplifiers may work with very low frequencies down to direct current. Amplifiers can also be categorized by their physical placement in the signal chain; a preamplifier may precede other signal processing stages, for example. The first practical electrical device which could amplify was the triode vacuum tube, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. Today most amplifiers use transistors.
Loxley was a friend of Benjamin Franklin and helped make many of his electrostatic machines. He assisted Franklin in his electrical experiments. Loxley provided his house key that Franklin used to get lightning from flying a kite in the clouds. The kite experiment became known as a variant of the "Philadelphia Experiment" of 1752.
The legendary Ford Mustang, the first of the "pony" cars, was developed and introduced in 1964 under the guidance of Lee Iacocca (Lehigh Class of 1946), former general manager of Ford Motor Company's Ford Division. Still in production, the Mustang combined fun, performance and styling at a low price and had the most successful first year sales of any automobile. In its first two years of production, three Ford Motor Company plants produced nearly 1.5 million Mustangs, a record unequaled before or since.
Mahlon Loomis (21 July 1826 – 13 October 1886) was an American dentist and inventor. He is best known for promoting the idea that the Earth's upper atmosphere was divided into discrete concentric layers, and these layers could be tapped by metallic conductors on hills and mountain tops, in order to provide long-distance wireless telegraph and telephone communication, as well as draw electricity down to the Earth's surface.
Robert Fuller (born Leonard Leroy "Buddy" Lee, July 29, 1933), is an American horse rancher and retired actor. He began his career on television, guest-starring primarily on Western programs, while appearing in two movies: "The Brain from Planet Arous" and "Teenage Thunder" (both in 1957).
About 20 years later, John Ambrose Fleming (scientific adviser to the Marconi Company
and former Edison employee) realized that the Edison effect could be used as a radio detector. Fleming patented the first true thermionic diode, the Fleming valve, in Britain on November 16, 1904 (followed by in November 1905).
Reginald Aubrey Fessenden (October 6, 1866 – July 22, 1932) was a Canadian-born inventor, who did a majority of his work in the United States and also claimed U.S. citizenship through his American-born father. During his life he received hundreds of patents in various fields, most notably ones related to radio and sonar.
The first practical device that could amplify was the triode vacuum tube, invented in 1906 by Lee De Forest, which led to the first amplifiers around 1912. Vacuum tubes were used in almost all amplifiers until the 1960s–1970s when the transistor, invented in 1947, replaced them. Today, most amplifiers use transistors, but vacuum tubes continue to be used in some applications.
The development of audio communication technology in form of the telephone, first patented in 1876, created the need to increase the amplitude of electrical signals to extend the transmission of signals over increasingly long distances. In telegraphy, this problem had been solved with intermediate devices at stations that replenished the dissipated energy by operating a signal recorder and transmitter back-to-back, forming a relay, so that a local energy source at each intermediate station powered the next leg of transmission.
For duplex transmission, i.e. sending and receiving in both directions, bi-directional relay repeaters were developed starting with the work of C. F. Varley for telegraphic transmission. Duplex transmission was essential for telephony and the problem was not satisfactorily solved until 1904, when H. E. Shreeve of the American Telephone and Telegraph Company improved existing attempts at constructing a telephone repeater consisting of back-to-back carbon-granule transmitter and electrodynamic receiver pairs. The Shreeve repeater was first tested on a line between Boston and Amesbury, MA, and more refined devices remained in service for some time. After the turn of the century it was found that negative resistance mercury lamps could amplify, and were also tried in repeaters, with little success.
Fuller was born as Leonard Leroy Lee on July 29, 1933, in Troy, New York, the only child of Betty Simpson, a dance instructor. Prior to his birth, Betty married Robert Simpson, Sr., a Naval Academy officer. In 1939, at the age of 6, his family moved to Key West, Florida, where, already known by the nickname of "Buddy," he took the name Robert Simpson Jr. The early highlights of his life were acting and dancing. His parents owned a dancing school in Florida. His family also moved to Chicago, Illinois, where they lived for 1 year, before moving back to Florida. Simpson Jr., as he was then still formally known, attended the Miami Military School for fifth and sixth grade, and Key West High School for ninth grade. He dropped out in 1948, at the age of 14, due to the fact that he disliked school and was doing poorly there. In 1950, at the age of 16, he traveled with his family to Hollywood, California, where his first job was as a stunt man. He also worked at Grauman's Chinese Theatre, beginning as a doorman and working his way up to Assistant Manager by age 18. At the urging of friends, the up-to-then Simpson Jr. joined the Screen Actors Guild, embarked on a career in acting, and changed his name from Robert Simpson Jr. to Robert Fuller, the name by which he would be known at his most prominent.
Litke's wireless microphone was first tested at the Olympic trials held at Stanford University in 1959. Next, the American Broadcasting Company (ABC television) tested the microphone at the Democratic and Republican Conventions in 1960. Candidates John F. Kennedy and Richard Nixon were among the first celebrities to use the Vega-Mike. TV anchor John Daly praised Litke's invention on the ABC television news broadcast in July 1960. Daly introduced it to Americans with the words: "This is a Vega-Mike" and went on to explain it "is a wireless microphone, six inches long... without any wires of any kind..." Daly pointed out it could be used to broadcast "within the (convention) hall or outside... without the inconvenience of interconnecting microphone cables..." Even the Federal Communication Commission was impressed with it. The FCC gave him 12 frequencies instead of the one he was seeking.
Thomas A. Edison invented the phonograph, the first device for recording and playing back sound, in 1877. After patenting the invention and benefiting from the publicity and acclaim it received, Edison and his laboratory turned their attention to the commercial development of electric lighting, playing no further role in the development of the phonograph for nearly a decade. Edison's original phonograph recorded on sheets of tinfoil and was little more than a crude curiosity, although one that fascinated much of the public. These earliest phonographs were sold mainly to entrepreneurs who made a living out of traveling around the country giving "educational" lectures in hired halls or otherwise demonstrating the device to audiences for a fee. The tinfoil phonograph was not fit for any real practical use and public interest soon waned.
De Forest was born in Randers, Denmark, to a Danish mother, Marianna Birgitte Gudnitz and Swedish father, Ingvar de Forest (1938–2010). Following her parents' divorce when she was young, she grew up with her mother in Mariager, Denmark, and in Stockholm, Sweden. She had previously claimed that she was a great granddaughter of British king Edward VII. Danmarks Radio used the story of her claim to royal ancestry in its promotion of the Dansk Melodi Grand Prix, although the claim has been discredited by researchers.
On July 18, 1907, de Forest made the first ship-to-shore transmissions by radiotelephone — race reports for the Annual Inter-Lakes Yachting Association (I-LYA) Regatta held on Lake Erie — which were sent from the steam yacht "Thelma" to his assistant, Frank E. Butler, located in the Fox's Dock Pavilion on South Bass Island. De Forest also interested the U.S. Navy in his radiotelephone, which placed a rush order to have 26 arc sets installed for its Great White Fleet around-the-world voyage that began in late 1907. However, at the conclusion of the circumnavigation the sets were declared to be too unreliable to meet the Navy's needs and removed.
De Forest's father was a Congregational Church minister who hoped his son would also become a pastor. In 1879 the elder de Forest became president of the American Missionary Association's Talladega College in Talladega, Alabama, a school "open to all of either sex, without regard to sect, race, or color", and which educated primarily African-Americans. Many of the local white citizens resented the school and its mission, and Lee spent most of his youth in Talladega isolated from the white community, with several close friends among the black children of the town.
Although raised in a strongly religious Protestant household, de Forest later became an agnostic. In his autobiography, he wrote that in the summer of 1894 there was an important shift in his beliefs: "Through that Freshman vacation at Yale I became more of a philosopher than I have ever since. And thus, one by one, were my childhood's firm religious beliefs altered or reluctantly discarded."