When was the transistor radio invented?
Transistor radio
A transistor radio is a small portable radio receiver that uses transistor-based circuitry. Following their development in 1954, made possible by the invention of the transistor in 1947, they became the most popular electronic communication device in history, with billions manufactured during the 1960s and 1970s. Their pocket size sparked a change in popular music listening habits, allowing people to listen to music anywhere they went. Beginning in the 1980s, however, cheap AM transistor radios were superseded by devices with higher audio quality such as portable CD players, personal audio players, boomboxes, and (eventually) smartphones, some of which contain radios themselves.
History of the transistor
Further developments included the grown-junction transistor (1951), the surface-barrier transistor (1953), the diffusion transistor, the tetrode transistor, and the pentode transistor. The diffused silicon 'mesa transistor' was developed at Bell in 1955 and made commercially available by Fairchild Semiconductor in 1958. The spacistor was a type of transistor developed in the 1950s as an improvement over the point-contact transistor and the later alloy junction transistor.
Transistor
From November 17, 1947, to December 23, 1947, John Bardeen and Walter Brattain at AT&T's Bell Labs in Murray Hill, New Jersey of the United States performed experiments and observed that when two gold point contacts were applied to a crystal of germanium, a signal was produced with the output power greater than the input. Solid State Physics Group leader William Shockley saw the potential in this, and over the next few months worked to greatly expand the knowledge of semiconductors. The term "transistor" was coined by John R. Pierce as a contraction of the term "transresistance". According to Lillian Hoddeson and Vicki Daitch, authors of a biography of John Bardeen, Shockley had proposed that Bell Labs' first patent for a transistor should be based on the field-effect and that he be named as the inventor. Having unearthed Lilienfeld’s patents that went into obscurity years earlier, lawyers at Bell Labs advised against Shockley's proposal because the idea of a field-effect transistor that used an electric field as a "grid" was not new. Instead, what Bardeen, Brattain, and Shockley invented in 1947 was the first point-contact transistor. In acknowledgement of this accomplishment, Shockley, Bardeen, and Brattain were jointly awarded the 1956 Nobel Prize in Physics "for their researches on semiconductors and their discovery of the transistor effect".
Timeline of United States inventions (1946–1991)
In electronics, a transistor is a semiconductor device commonly used to amplify or switch electronic signals. Because the controlled output power can be much larger than the controlling input power, the transistor provides amplification of a signal. The transistor is the fundamental building block of all modern electronic devices, and is used in radio, telephone, computer, and other electronic systems. From November 17, 1947 to December 23, 1947, John Bardeen and Walter Brattain at AT&T Bell Labs, underwent experimentations and finally observed that when two gold point contacts were applied to a crystal of germanium, a signal was produced whereby the output power was larger than the input. The manager of the Bell Labs semiconductor research group, William Shockley, saw the potential in this and worked over the next few months greatly expanding the knowledge of semiconductors in order to construct the first point-contact transistor. Shockley is considered by many to be the "father" of the transistor. Hence, in recognition of his work, the transistor is widely, yet not universally acknowledged as the most important invention of the entire 20th century since it forms today's building blocks of processors found and used in almost every modern computing and electronics device. In recognition of their invention of the transistor, Shockley, Bardeen and Brattain were jointly awarded the 1956 Nobel Prize in Physics.
Gilbert Davey
When transistors first became available to amateurs in the mid-1950s, Davey was initially cautious, believing that their initial high price and variable performance made them an expensive risk for young constructors. However he soon relaxed these reservations, and his first transistor radio design appeared in Boy's Own Paper in January 1957. The title "Make a Cold Valve Set" summed up the novelty of the transistor.
History of the transistor
The TR-55 was quite similar to the Regency TR-1 in many ways, being powered by the same sort of 22.5-volt battery, and was not much more practical. Note: according to the schematic, the TR-55 used a 6 volt supply. Very few were distributed outside Japan. It was not until 1957 that Sony produced their ground-breaking "TR-63" shirt pocket radio, a much more advanced design that ran on a standard 9-volt battery and could compete favorably with vacuum tube portables. The TR-63 was also the first transistor radio to use all miniature components. (The term "pocket" was a matter of some interpretation, as Sony allegedly had special shirts made with oversized pockets for their salesmen.)
Heinrich Welker
Heinrich Johann Welker (September 9, 1912 in Ingolstadt – December 25, 1981 in Erlangen) was a German theoretical and applied physicist who invented the "transistron", a transistor made at Westinghouse independently of the first successful transistor made at Bell Laboratories. He did fundamental work in III-V compound semiconductors, and paved the way for microwave semiconductor elements and laser diodes.
Digital Revolution
In 1947, the transistor was invented, leading the way to more advanced digital computers. From the late 1940s, Universities, the Military, and Business developed computer systems, to digitally replicate and automate previously manually performed mathematical calculations, with the LEO (computer) being the first commercially available general purpose computer.
Ralph Bown
Bown's work focused on electromagnetic propagation, particularly for radio broadcasting, ship-to-shore communication, aircraft radios, and intercontinental telephony. He was also an expert in radar, and served as a division member and consultant of the National Defense Research Committee and expert consultant to the Secretary of War; in 1941 he visited England to study radar in combat operations. Bown became research director at Bell Labs, and on June 30, 1948, led a press conference announcing the invention of the transistor.
Goldschmidt alternator
The heyday of the big alternator radio transmitters was around 1918. World War I had brought home to nations the strategic importance of radio communication, as without it they could easily be isolated by enemies cutting their submarine telegraph cables. This precipitated a postwar building boom of large transcontinental alternater radio stations. However these expensive behemoths were obsolete even as they were installed. The invention of the triode vacuum tube in 1906 by Lee De Forest, and the feedback oscillator circuit in 1912 by Edwin Armstrong and Alexander Meissner, made possible smaller and cheaper vacuum tube transmitters which by the end of World War 1 could produce as much radio power as the alternators. By 1921 the Marconi Co. had installed 100 kW vacuum tube transmitters for transatlantic message traffic at its stations at Carnarvon, Wales and Glace Bay, Newfoundland. Due to their huge capitol costs, legacy alternator transmitters remained in use through about 1930. It is not known when the last Goldschmidt machine was retired.
Telephony
Starting with the introduction of the transistor, invented in 1947 by Bell Laboratories, to amplification and switching circuits in the 1950s, and through development of computer-based electronic switching systems, the public switched telephone network (PSTN) has gradually evolved towards automation and digitization of signaling and audio transmissions.
Chuck Colby
Colby's first invention was the Colby TR-2 transistor radio, which he designed at the precocious age of 12 and sold to family, friends and customers on his paper-route, and is possibly the first pocket transistor radio. At 15, he built for his high school science project the world's first home earth satellite station capable of receiving signals from the Russian satellite Sputnik. As a college student, his passion for radio and inventing brought him attention in the LA Times when he and a friend built their own TV stations to broadcast video to each other over the airwaves. Shortly afterwards, he built a video security system for use by NASA.
History of the transistor
The key to the development of the transistor was the further understanding of the process of the electron mobility in a semiconductor. It was realized that if there was some way to control the flow of the electrons from the emitter to the collector of this newly discovered diode (discovered 1874; patented 1906), one could build an amplifier. For instance, if one placed contacts on either side of a single type of crystal the current would not flow through it. However, if a third contact could then "inject" electrons or holes into the material, the current would flow.
Transistor
The thermionic triode, a vacuum tube invented in 1907, enabled amplified radio technology and long-distance telephony. The triode, however, was a fragile device that consumed a substantial amount of power. In 1909 physicist William Eccles discovered the crystal diode oscillator. Physicist Julius Edgar Lilienfeld filed a patent for a field-effect transistor (FET) in Canada in 1925 , which was intended to be a solid-state replacement for the triode. Lilienfeld also filed identical patents in the United States in 1926 and 1928. However, Lilienfeld did not publish any research articles about his devices nor did his patents cite any specific examples of a working prototype. Because the production of high-quality semiconductor materials was still decades away, Lilienfeld's solid-state amplifier ideas would not have found practical use in the 1920s and 1930s, even if such a device had been built. In 1934, German inventor Oskar Heil patented a similar device in Europe.
Invention of radio
In 1900, construction began on a large radio transmitting alternator. Fessenden, experimenting with a high-frequency spark transmitter, successfully transmitted speech on December 23, 1900, over a distance of about , the "first audio radio transmission". Early in 1901 the Weather Bureau officially installed Fessenden at Wier's Point, Roanoke Island, North Carolina, and he made experimental transmissions across water to a station located about west of Cape Hatteras, the distance between the two stations being almost exactly . An alternator of 1 kW output at 10 kilohertz was built in 1902. The credit for the development of this machine is due to Charles Proteus Steinmetz, Caryl D. Haskins, Ernst Alexanderson, John T. H. Dempster, Henry Geisenhoner, Adam Stein, Jr., and F. P. Mansbendel.
Transistor radio
In August 1955, while still a small company, Tokyo Telecommunications Engineering Corporation introduced their TR-55 five-transistor radio under the new brand name Sony. With this radio, Sony became the first company to manufacture the transistors and other components they used to construct the radio. The TR-55 was also the first transistor radio to utilize all miniature components. It is estimated that only 5,000 to 10,000 units were produced.
Radio receiver
The reflex receiver, invented in 1914 by Wilhelm Schloemilch and Otto von Bronk, and rediscovered and extended to multiple tubes in 1917 by Marius Latour and William H. Priess, was a design used in some inexpensive radios of the 1920s which enjoyed a resurgence in small portable tube radios of the 1930s and again in a few of the first transistor radios in the 1950s. It is another example of an ingenious circuit invented to get the most out of a limited number of active devices. In the reflex receiver the RF signal from the tuned circuit is passed through one or more amplifying tubes or transistors, demodulated in a detector, then the resulting audio signal is passed "again" though the same amplifier stages for audio amplification. The separate radio and audio signals present simultaneously in the amplifier do not interfere with each other since they are at different frequencies, allowing the amplifying tubes to do "double duty". In addition to single tube reflex receivers, some TRF and superheterodyne receivers had several stages "reflexed". Reflex radios were prone to a defect called "play-through" which meant that the volume of audio did not go to zero when the volume control was turned down.
Transistor
The first working silicon transistor was developed at Bell Labs on January 26, 1954 by Morris Tanenbaum. The first commercial silicon transistor was produced by Texas Instruments in 1954. This was the work of Gordon Teal, an expert in growing crystals of high purity, who had previously worked at Bell Labs. The first MOSFET actually built was by Kahng and Atalla at Bell Labs in 1960.
History of the transistor
The Bell team made many attempts to build such a system with various tools, but generally failed. Setups where the contacts were close enough were invariably as fragile as the original cat's whisker detectors had been, and would work briefly, if at all. Eventually they had a practical breakthrough. A piece of gold foil was glued to the edge of a triangular plastic wedge, and then the foil was sliced with a razor at the tip of the triangle. The result was two very closely spaced contacts of gold. When the plastic was pushed down onto the surface of a crystal and voltage applied to the other side (on the base of the crystal), current started to flow from one contact to the other as the base voltage pushed the electrons away from the base towards the other side near the contacts. The point-contact transistor had been invented.
History of Chrysler
In 1955 things brightened with the introduction of Virgil Exner's successful Forward Look designs, followed in 1956 by Chrysler's pioneering adoption of transistor radios in cars. On April 28, 1955, Chrysler and Philco had announced the development and production of the world's first all-transistor car radio. The Mopar model 914HR was developed and produced by Chrysler and Philco and was an $150.00 "option" on the 1956 Imperial automobile models. Philco was the company that had manufactured the all-transistor car radio Mopar model 914HR, starting in the fall of 1955 at its Sandusky, Ohio plant, for the Chrysler corporation. 
With the inauguration of the second generation Forward Look cars for 1957, Torsion-Aire suspension was introduced. This was not air suspension, but an indirect-acting, torsion-spring front suspension system which drastically reduced unsprung weight and shifted the car's center of gravity downward and rearward. This resulted in both a smoother ride and significantly improved handling. A rush to production of the 1957 models led to quality control problems including poor body fit and finish, resulting in significant and early rusting. This, coupled with a national recession, found the company again in recovery mode.
Magnetic detector
The magnetic detector or Marconi magnetic detector, sometimes called the "Maggie", was an early radio wave detector used in some of the first radio receivers to receive Morse code messages during the wireless telegraphy era around the turn of the 20th century. Developed in 1902 by radio pioneer Guglielmo Marconi from a method invented in 1895 by New Zealand physicist Ernest Rutherford it was used in Marconi wireless stations until around 1912, when it was superseded by vacuum tubes. It was widely used on ships because of its reliability and insensitivity to vibration. A magnetic detector was part of the wireless apparatus in the radio room of the RMS "Titanic" which was used to summon help during its famous 15 April 1912 sinking.
History of Sony
In the early 1950s, Ibuka traveled in Asia and heard about Bell Labs' invention of the transistor. He convinced Bell to license the transistor technology to his Japanese company. While most Japanese companies were researching the transistor for its military applications, Ibuka and Morita looked to apply it to communications. Although the American companies Regency Electronics and Texas Instruments built the first transistor radio as joint venture, it was Ibuka's company that made them commercially successful for the first time.
Sonotone 1010
The Sonotone 1010 hearing aid, introduced on 29 December 1952, was the first commercial product to use transistors, which had been invented five years earlier in 1947.
Headphones
Smaller earbud type earpieces, which plugged into the user's ear canal, were first developed for hearing aids. They became widely used with transistor radios, which commercially appeared in 1954 with the introduction of the Regency TR-1. The most popular audio device in history, the transistor radio changed listening habits, allowing people to listen to radio anywhere. The earbud uses either a moving iron driver or a piezoelectric crystal to produce sound. The 3.5 mm radio and phone connector, which is the most commonly used in portable application today, has been used at least since the Sony EFM-117J transistor radio, which was released in 1964. Its popularity was reinforced with its use on the Walkman portable tape player in 1979.
History of electrical engineering
The invention of the transistor in 1947 by William B. Shockley, John Bardeen and Walter Brattain opened the door for more compact devices and led to the development of the integrated circuit in 1958 by Jack Kilby and independently in 1959 by Robert Noyce. In the mid to late 1950s, the term radio engineering gradually gave way to the name electronics engineering, which then became a stand-alone university degree subject, usually taught alongside electrical engineering with which it had become associated due to some similarities. In 1968 Marcian Hoff invented the first microprocessor at Intel and thus ignited the development of the personal computer. The first realization of the microprocessor was the Intel 4004, a 4-bit processor developed in 1971, but only in 1973 did the Intel 8080, an 8-bit processor, make the building of the first personal computer, the Altair 8800, possible.
History of radio
In 1894 the young Italian inventor Guglielmo Marconi began working on the idea of building a commercial wireless telegraphy system based on the use of Hertzian waves (radio waves), a line of inquiry that he noted other inventors did not seem to be pursuing. Marconi read through the literature and used the ideas of others who were experimenting with radio waves but did a great deal to develop devices such as portable transmitters and receiver systems that could work over long distances, turning what was essentially a laboratory experiment into a useful communication system. By August 1895 Marconi was field testing his system but even with improvements he was only able to transmit signals up to one-half mile, a distance Oliver Lodge had predicted in 1894 as the maximum transmission distance for radio waves. Marconi raised the height of his antenna and hit upon the idea of grounding his transmitter and receiver. With these improvements the system was capable of transmitting signals up to and over hills. Marconi's experimental apparatus proved to be the first engineering-complete, commercially successful radio transmission system. Marconi's apparatus is also credited with saving the 700 people who survived the tragic "Titanic" disaster.
Texas Instruments
Texas Instruments emerged in 1951 after a reorganization of Geophysical Service Incorporated, a company founded in 1930 that manufactured equipment for use in the seismic industry, as well as defense electronics. TI produced the world's first commercial silicon transistor in 1954, and designed and manufactured the first transistor radio in 1954. Jack Kilby invented the integrated circuit in 1958 while working at TI's Central Research Labs. TI also invented the hand-held calculator in 1967, and introduced the first single-chip microcontroller (MCU) in 1970, which combined all the elements of computing onto one piece of silicon.
History of the transistor
Prototypes of all-transistor AM radio receivers were demonstrated, but were really only laboratory curiosities. However, in 1950 Shockley developed a radically different type of solid-state amplifier which became known as the bipolar junction "transistor". Although it works on a completely different principle to the point-contact "transistor", this is the device which is most commonly referred to as simply a "transistor" today. Morgan Sparks made the bipolar junction transistor into a practical device. These were also licensed to a number of other electronics companies, including Texas Instruments, who produced a limited run of transistor radios as a sales tool. Early transistors were chemically unstable and only suitable for low-power, low-frequency applications, but as transistor design developed, these problems were slowly overcome.
History of radio
In 1933, FM radio was patented by inventor Edwin H. Armstrong. FM uses frequency modulation of the radio wave to reduce static and interference from electrical equipment and the atmosphere. In 1937, W1XOJ, the first experimental FM radio station, was granted a construction permit by the US Federal Communications Commission (FCC). In the 1930s, regular analog television broadcasting began in some parts of Europe and North America. By the end of the decade there were roughly 25,000 all-electronic television receivers in existence worldwide, the majority of them in the UK. In the US, Armstrong's FM system was designated by the FCC to transmit and receive television sound.
Trans-Oceanic
In November 1957 the first of several transistorized Trans-Oceanics was introduced, the Royal 1000. As had always been the case, Commander E. McDonald helped in the design of the 1000. This was his last endeavor in the Trans-Oceanic radio before he died soon after its introduction. The Royal 1000 had exactly the same frequency coverage as the A/B 600 series tube Trans-Oceanics with the addition of the 13/meter band. The new Royal 1000 also had an all-metal cabinet design with the front cover opening to the down position. The log chart was located inside the flip-down door. Very early Royal 1000s sported a genuine leather covering marked as such. Another first for portable radios was the unique dial scale used in the 1000 and later series of Trans-Oceanics. The 1000 was designed with a cylinder dial scale that would rotate with the band switch allowing only that particular band scale to show.
Transistor radio
Since 1980, the popularity of portable radios has declined with the rise of portable audio players and smartphones, which allow users to carry and listen to the music of their choosing and may also include a radio tuner. This began in the late 1970s with boom boxes and portable cassette players such as the Sony Walkman, followed by portable CD players. A common type now is the portable digital audio player. This type of device is a popular choice with listeners who are dissatisfied with terrestrial music radio because of a limited selection of music and reception problems. However, transistor radios are still popular for news, talk radio, weather, live sporting events and emergency alert applications.
Transistor computer
The Philco Transac models S-1000 scientific computer and S-2000 electronic data processing computer were early commercially produced large-scale all-transistor computers; they were announced in 1957 but did not ship until sometime after the fall of 1958. The Philco computer name "Transac" stands for Transistor-Automatic-Computer. Both of these Philco computer models used the surface-barrier transistor in their circuitry designs, the world's first high-frequency transistor suitable for high-speed computers. The surface-barrier transistor was developed by Philco in 1953.
History of hearing aids
Zenith was the first company to realize the problem with transistors was the body heat of individuals. After coming to this conclusion, the first “all-transistor” hearing aids were offered in 1952, called the Microtone Transimatic and the Maico Transist-ear. In 1954, the company, Texas Instruments, produced a silicon transistor, which was much more effective than the previous version. The end of the transistor was marked by the creation of the integrated circuit or IC by Jack Kilby at Texas Instruments in 1958 and the technique was perfected in hearing aids over the next 20 years.
History of the transistor
The production of the first commercially successful transistor radio is often incorrectly attributed to Sony (originally Tokyo Tsushin Kogyo). However the Regency TR-1, made by the Regency Division of I.D.E.A. (Industrial Development Engineering Associates) of Indianapolis, Indiana, was the first practical transistor radio made in any significant numbers. The TR-1 was announced on October 18, 1954 and put on sale in November 1954 for $49.95 (the equivalent of about $361 in year-2005 dollars) and sold about 150,000 units.
Walter Houser Brattain
On December 23, 1947, Walter Brattain, John Bardeen, and William B. Shockley demonstrated the first working transistor to their colleagues at Bell Laboratories. Amplifying small electrical signals and supporting the processing of digital information, the transistor is "the key enabler of modern electronics". The three men received the Nobel Prize in Physics in 1956 "for research on semiconductors and the discovery of the transistor effect."
Texas Instruments
In 1954, Texas Instruments designed and manufactured the first transistor radio. The Regency TR-1 used germanium transistors, as silicon transistors were much more expensive at the time. This was an effort by Haggerty to increase market demand for transistors.
Invention of radio
Marconi transmitted from England to Canada and the United States. In this period, a particular electromagnetic receiver, called the "Marconi magnetic detector" or "hysteresis magnetic detector", was developed further by Marconi and was successfully used in his early transatlantic work (1902) and in many of the smaller stations for a number of years. In 1902, a Marconi station was established in the village of Crookhaven, County Cork, Ireland to provide marine radio communications to ships arriving from the Americas. A ship's master could contact shipping line agents ashore to enquire which port was to receive their cargo without the need to come ashore at what was the first port of landfall. Ireland was also, due to its western location, to play a key role in early efforts to send trans-Atlantic messages. Marconi transmitted from his station in Glace Bay, Nova Scotia, Canada across the Atlantic, and on 18 January 1903 a Marconi station sent a message of greetings from Theodore Roosevelt, the President of the United States, to the King of the United Kingdom, marking the first transatlantic radio transmission originating in the United States
History of radio
Around the start of the 20th century, the Slaby-Arco wireless system was developed by Adolf Slaby and Georg von Arco. In 1900, Reginald Fessenden made a weak transmission of voice over the airwaves. In 1901, Marconi conducted the first successful transatlantic experimental radio communications. In 1904, The U.S. Patent Office reversed its decision, awarding Marconi a patent for the invention of radio, possibly influenced by Marconi's financial backers in the States, who included Thomas Edison and Andrew Carnegie. This also allowed the U.S. government (among others) to avoid having to pay the royalties that were being claimed by Tesla for use of his patents. For more information see Marconi's radio work. In 1907, Marconi established the first commercial transatlantic radio communications service, between Clifden, Ireland and Glace Bay, Newfoundland.
Amplifier
The replacement of bulky electron tubes with transistors during the 1960s and 1970s created another revolution in electronics, making possible a large class of portable electronic devices, such as the transistor radio developed in 1954. Today, use of vacuum tubes is limited for some high power applications, such as radio transmitters.
Semiconductor device
The static induction transistor, the first high frequency transistor, was invented by Japanese engineers Jun-ichi Nishizawa and Y. Watanabe in 1950. It was the fastest transistor through to the 1980s.
Transistor
The first "prototype" pocket transistor radio was shown by INTERMETALL (a company founded by Herbert Mataré in 1952) at the "Internationale Funkausstellung Düsseldorf" between August 29, 1953 and September 9, 1953.
AM broadcasting
Unlike telegraph and telephone systems, which used completely different types of equipment, most radio receivers were equally suitable for both radiotelegraph and radiotelephone reception. In 1903 and 1904 the electrolytic detector and thermionic diode (Fleming valve) were invented by Reginald Fessenden and John Ambrose Fleming, respectively. Most important, in 1904–1906 the crystal detector, the simplest and cheapest AM detector, was developed by G. W. Pickard. Homemade crystal radios spread rapidly during the next 15 years, providing ready audiences for the first radio broadcasts. One limitation of crystals sets was the lack of amplifying the signals, so listeners had to use earphones, and it required the development of vacuum-tube receivers before loudspeakers could be used. The dynamic cone loudspeaker, invented in 1924, greatly improved audio frequency response over the previous horn speakers, allowing music to be reproduced with good fidelity. AM radio offered the highest sound quality available in a home audio device prior to the introduction of the high-fidelity, long-playing record in the late 1940s.
History of the transistor
The world’s first transistor computer was built at the University of Manchester in November 1953. The computer was built by Richard Grimsdale, then a research student in the Department of Electrical Engineering and later a Professor of Electronic Engineering at Sussex University. The machine used point-contact transistors, made in small quantities by STC and Mullard. These consisted of a single crystal of germanium with two fine wires, resembling the crystal and cat’s whisker of the 1920s. These transistors had the useful property that a single transistor could possess two stable states. ... The development of the machine was severely hampered by the unreliability of the transistors, which consumed 150 watts.
Transistor
The first bipolar junction transistors were invented by Bell Labs' William Shockley, which applied for patent (2,569,347) on June 26, 1948. On April 12, 1950, Bell Labs chemists Gordon Teal and Morgan Sparks had successfully produced a working bipolar NPN junction amplifying germanium transistor. Bell Labs had announced the discovery of this new "sandwich" transistor in a press release on July 4, 1951.
Radio receiver
Beginning around 1905 continuous wave (CW) transmitters began to replace spark transmitters for radiotelegraphy because they had much greater range. The first continuous wave transmitters were the Poulsen arc invented in 1904 and the Alexanderson alternator developed 1906-1910, which were replaced by vacuum tube transmitters beginning around 1920.
Rufus P. Turner
Rufus Paul Turner (December 25, 1907 – March 25, 1982) was an academic, engineer, and author who published on semiconductor devices, technical writing style, and poet-novelist Charlotte Turner Smith. After three decades working with electronic devices – including developing the first practical transistor radio – he earned a doctorate in literature at age 52 and became an English professor. He wrote over 40 books and 3000 articles during his six-decade career.
Transmitter
The invention of the transistor allowed the development in the 1960s of small portable transmitters such as wireless microphones, garage door openers and walkie-talkies. The development of the integrated circuit (IC) in the 1970s made possible the current proliferation of wireless devices, such as cell phones and laptops, in which integrated digital transmitters and receivers in wireless modems operate automatically, in the background, to exchange data with wireless networks.
Radio broadcasting in Australia
The transistor radio first appeared on the market in 1954. In particular, it made portable radios even more transportable. All sets quicklly became smaller, cheaper and more convenient. The aim of radio manufacturers became a radio in every room, in the car, and in the pocket.
Bell Labs
In 1947, the transistor, probably the most important invention developed by Bell Laboratories, was invented by John Bardeen, Walter Houser Brattain, and William Bradford Shockley (and who subsequently shared the Nobel Prize in Physics in 1956). In 1947, Richard Hamming invented Hamming codes for error detection and correction. For patent reasons, the result was not published until 1950. In 1948, "A Mathematical Theory of Communication", one of the founding works in information theory, was published by Claude Shannon in the "Bell System Technical Journal". It built in part on earlier work in the field by Bell researchers Harry Nyquist and Ralph Hartley, but it greatly extended these. Bell Labs also introduced a series of increasingly complex calculators through the decade. Shannon was also the founder of modern cryptography with his 1949 paper "Communication Theory of Secrecy Systems".In 1952, William Gardner Pfann revealed the method of zone melting which enabled semiconductor purification and level doping.
Surface-barrier transistor
The world's first all-transistor car radio, was developed and produced by Chrysler and Philco in 1955. Chrysler offered this all-transistor car radio, Mopar model 914HR, available as an "option" in the fall of 1955, for its new line of 1956 Chrysler and Imperial cars. Philco was the manufacturer of these all-transistor car radios for the Chrysler Corporation and had also used its surface-barrier transistors in the radio's circuitry design.
Invention of radio
It had been proposed in 1879 to German physicist Heinrich Rudolf Hertz that he try to prove Maxwell's theory of electromagnetism but he could not see any way to build an apparatus to experimentally test the theory. His observation, in the autumn of 1886, of discharging a Leyden jar into a large coil producing a spark in an adjacent coil gave him the idea of how to build a test apparatus. Between 1886 and 1888 Hertz conducted scientific experiments that validated Maxwell's theory. He designed a method of detecting spark-gap radio waves by observing that another unpowered spark-gap, acting as an antenna, would absorb the radio energy and convert it back into an electric spark. Hertz published his results in a series of papers between 1887 and 1890, and again in complete book form in 1893.
Crystal radio
Indian physicist Jagadish Chandra Bose was first to use a crystal as a radio wave detector, using galena detectors to receive microwaves starting around 1894. In 1901, Bose filed for a U.S. patent for "A Device for Detecting Electrical Disturbances" that mentioned the use of a galena crystal; this was granted in 1904, #755840. The device depended on the large variation of a semiconductor's conductance with temperature; today we would call his invention a bolometer. Bose's patent is frequently, but erroneously, cited as a type of rectifying detector. On August 30, 1906, Greenleaf Whittier Pickard filed a patent for a silicon crystal detector, which was granted on November 20, 1906.
Magnetic detector
The primitive spark gap radio transmitters used during the first three decades of radio (1886-1916) could not transmit audio (sound) and instead transmitted information by wireless telegraphy; the operator switched the transmitter on and off with a telegraph key, creating pulses of radio waves to spell out text messages in Morse code. So the radio receiving equipment of the time did not have to convert the radio waves into sound like modern receivers, but merely detect the presence or absence of the radio signal. The device that did this was called a detector. The first widely used detector was the coherer, invented in 1890.
Semiconductor device
Semiconductors had been used in the electronics field for some time before the invention of the transistor. Around the turn of the 20th century they were quite common as detectors in radios, used in a device called a "cat's whisker" developed by Jagadish Chandra Bose and others. These detectors were somewhat troublesome, however, requiring the operator to move a small tungsten filament (the whisker) around the surface of a galena (lead sulfide) or carborundum (silicon carbide) crystal until it suddenly started working. Then, over a period of a few hours or days, the cat's whisker would slowly stop working and the process would have to be repeated. At the time their operation was completely mysterious. After the introduction of the more reliable and amplified vacuum tube based radios, the cat's whisker systems quickly disappeared. The "cat's whisker" is a primitive example of a special type of diode still popular today, called a Schottky diode.
Gordon Kidd Teal
When William Shockley's group at Bell Labs invented the transistor in 1947 Teal realized that substantial improvements in the device would result if it was fabricated using a single crystal, rather than the polycrystalline material then being used. He started a "boot-leg" project with very few resources or managerial support to make a simple crystal.
Invention of radio
By the summer of 1906, a machine producing 50 kilohertz was installed at the Brant Rock station, and in the fall of 1906, what was called an electric alternating dynamo was working regularly at 75 kilohertz, with an output of 0.5 kW. Fessenden used this for wireless telephoning to Plymouth, Massachusetts, a distance of approximately . In the following year machines were constructed having a frequency of 96 kilohertz and outputs of 1 kW and 2 kW. Fessenden believed that the damped wave-coherer system was essentially and fundamentally incapable of development into a practical system. He would employ a two-phase high frequency "alternator method" and the continuous production of waves with changing constants of sending circuit. Fessenden would also use duplex and multiplex commutator methods. On December 11, 1906, operation of the wireless transmission in conjunction with the wire lines took place. In July 1907 the range was considerably extended and speech was successfully transmitted between Brant Rock and Jamaica, on Long Island, a distance of nearly , in daylight and mostly over land, the mast at Jamaica being approximately high.
Invention of radio
In late 1886, Reginald A. Fessenden began working directly for Thomas Edison at the inventor's new laboratory in West Orange, New Jersey. Fessenden quickly made major advances, especially in receiver design, as he worked to develop audio reception of signals. The United States Weather Bureau began, early in 1900, a systematic course of experimentation in wireless telegraphy, employing him as a specialist. Fessenden evolved the heterodyne principle here where two signals combined to produce a third signal.
Heinrich Welker
While at the Westinghouse subsidiary in Paris, Welker and German physicist Herbert F. Mataré developed a point contact semiconductor amplifier, demonstrated in June 1948. This coincided with the announcement by Bell laboratory scientists of the demonstration of a point contact transistor on June 30, 1948. The French Westinghouse subsidiary applied for a patent on the same type of device on August 13, 1948. On 18 May 1949, this European invention coined as the "Le Transistron" or the "French transistor" was presented to the public, while a first batch of 1,000 devices was manufactured for the French telecommunications. This development was an outgrowth of work done by the two independently in Germany in programs to develop German radar. The French patent was granted in 1952.
History of hearing aids
The development of transistors in 1948 by Bell Laboratories led to major improvements to the hearing aid. The transistor was invented by John Bardeen, Walter Brattain, and William Shockley. Transistors were created to replace vacuum tubes; they were small, required less battery power and had less distortion and heat than their predecessor. These vacuum tubes were typically hot and fragile, so the transistor was the ideal replacement.The 1952 Sonotone 1010 used a transistor stage along with vacuum tubes, to extend battery life. The size of these transistors led to developments in miniature, carbon microphones. These microphones could be mounted on various items, even eyeglasses. In 1951, Raytheon manufactured the transistor and was one of the first companies to mass-produce transistors to throughout America. Raytheon realized that their hearing aid only lasted short-term and began to sell the vacuum-tube hearing aids again along with transistor hearing aids.
Magnetic amplifier
In 1904 radio pioneer Reginald Fessenden placed an order for a high frequency rotary mechanical alternator from the General Electric Company capable of generate AC at a frequency of 100 kHz to be used for continuous wave radio transmission over great distances. The design job was given to General Electric engineer Ernst F. Alexanderson who developed the 2 kW Alexanderson alternator. By 1916 Alexanderson added a magnetic amplifier to control the transmission of these rotary alternators for transoceanic radio communication.
History of the transistor
An early witness of the phenomenon was Ralph Bray, a young graduate student. He joined the germanium effort at Purdue University in November 1943 and was given the tricky task of measuring the spreading resistance at the metal-semiconductor contact. Bray found a great many anomalies, such as internal high-resistivity barriers in some samples of germanium. The most curious phenomenon was the exceptionally low resistance observed when voltage pulses were applied. This effect remained a mystery because nobody realised, until 1948, that Bray had observed minority carrier injection - the effect that was identified by William Shockley at Bell Labs and made the transistor a reality.
Transistor radio
Chrysler and Philco announced that they had developed and produced the world's first all-transistor car radio in the April 28th 1955 edition of the Wall Street Journal. Chrysler made the all-transistor car radio, Mopar model 914HR, available as an "option" in fall 1955 for its new line of 1956 Chrysler and Imperial cars, which hit the showroom floor on October 21, 1955. The all-transistor car radio was a $150 option.
History of electronic engineering
Vacuum tubes remained the preferred amplifying device for 40 years, until researchers working for William Shockley at Bell Labs invented the transistor in 1947. In the following years, transistors made small portable radios, or transistor radios, possible as well as allowing more powerful mainframe computers to be built. Transistors were smaller and required lower voltages than vacuum tubes to work.
Semiconductor
Some of the properties of semiconductor materials were observed throughout the mid 19th and first decades of the 20th century. The first practical application of semiconductors in electronics was the 1904 development of the cat's-whisker detector, a primitive semiconductor diode used in early radio receivers. Developments in quantum physics in turn allowed the development of the transistor in 1947 and the integrated circuit in 1958.
History of the transistor
Scientists theorized that silicon would be easier to fabricate, but few bothered to investigate this possibility. Morris Tanenbaum et al. at Bell Laboratories were the first to develop a working silicon transistor on January 26, 1954. A few months later, Gordon Teal, working independently at Texas Instruments, developed a similar device. Both of these devices were made by controlling the doping of single silicon crystals while they were grown from molten silicon. A far superior method was developed by Morris Tanenbaum and Calvin S. Fuller at Bell Laboratories in early 1955 by the gaseous diffusion of donor and acceptor impurities into single crystal silicon chips.
History of the transistor
At the same time some European scientists were led by the idea of solid-state amplifiers. In August 1948 German physicists Herbert F. Mataré (1912–2011) and Heinrich Welker (1912–1981), working at Compagnie des Freins et Signaux Westinghouse in Aulnay-sous-Bois, France applied for a patent on an amplifier based on the minority carrier injection process which they called the "transistron". Since Bell Labs did not make a public announcement of the transistor until June 1948, the transistron was considered to be independently developed. Mataré had first observed transconductance effects during the manufacture of silicon diodes for German radar equipment during WWII. Transistrons were commercially manufactured for the French telephone company and military, and in 1953 a solid-state radio receiver with four transistrons was demonstrated at the Düsseldorf Radio Fair.
Transistor radio
While on a trip to the United States in 1952, Masaru Ibuka, founder of Tokyo Telecommunications Engineering Corporation (now Sony), discovered that AT&T was about to make licensing available for the transistor. Ibuka and his partner, physicist Akio Morita, convinced the Japanese Ministry of International Trade and Industry (MITI) to finance the $25,000 licensing fee (equivalent to $ today). For several months Ibuka traveled around the United States borrowing ideas from the American transistor manufacturers. Improving upon the ideas, Tokyo Telecommunications Engineering Corporation made its first functional transistor radio in 1954. Within five years, Tokyo Telecommunications Engineering Corporation grew from seven employees to approximately five hundred.
Computer
The bipolar transistor was invented in 1947. From 1955 onwards transistors replaced vacuum tubes in computer designs, giving rise to the "second generation" of computers.
Compared to vacuum tubes, transistors have many advantages: they are smaller, and require less power than vacuum tubes, so give off less heat. Silicon junction transistors were much more reliable than vacuum tubes and had longer, indefinite, service life. Transistorized computers could contain tens of thousands of binary logic circuits in a relatively compact space.
Megaphone
Although electronic public address systems have existed since vacuum tube amplifiers were developed in the early 1920s, vacuum tube versions were too heavy to be portable. Practical portable electric megaphones had to await the development of microelectronics which followed the invention of the transistor in 1947. In 1954, TOA Corporation developed the EM-202, the world's first transistorized megaphone.
TR-55
Akio Morita and Masaru Ibuka, then operating under the business name Tokyo Tsushin Kogyo, had been working on plans to introduce a transistor radio to the market since 1953. When the TR-55 was released in Japan in August 1955, it was the first transistor radio marketed in that country. The TR-55 featured the Sony name, but the company did not officially change its name to Sony until January 1958.
Valve audio amplifier
Valve radios and amplifiers were used in automobiles until they were displaced by transistorized radios. Transistors had the major advantage of working off the voltage provided by a car battery. Early radios required a power unit to convert the battery voltage to a value high enough for the valves. Later radios used special valves that were designed to operate directly from a 12 volt supply. These later radios were hybrid designs which used transistors only for the audio output stages because a 12 volt power amplifier valve was not practical. For this and other applications, transistors are smaller, cheaper, more durable, use less power, run cooler, and do not need to warm up.
TR-55
The TR-55's five transistors were designed in house by Sony, the technology having been licensed from Bell Labs. This made Sony the first company to produce commercial transistor radios from the ground up. American company Regency had launched their Regency TR-1 transistor radio earlier in 1954, but bought the transistors from Texas Instruments. Printed circuit boards were used, which was unusual for the time.
Antique radio
Transistor radios were available in many sizes from console to table-top to matchbox. Transistors are still used in today's radios, though the integrated circuit containing a large number of transistors has surpassed the use of singly packed transistors for the majority of radio circuitry.
History of computing hardware
At the University of Manchester, a team under the leadership of Tom Kilburn designed and built a machine using the newly developed transistors instead of valves. Initially the only devices available were germanium point-contact transistors, less reliable than the valves they replaced but which consumed far less power. Their first transistorised computer and the first in the world, was operational by 1953, and a second version was completed there in April 1955. The 1955 version used 200 transistors, 1,300 solid-state diodes, and had a power consumption of 150 watts. However, the machine did make use of valves to generate its 125 kHz clock waveforms and in the circuitry to read and write on its magnetic drum memory, so it was not the first completely transistorized computer.
Detector (radio)
In radio, a detector is a device or circuit that extracts information from a modulated radio frequency current or voltage. The term dates from the first three decades of radio (1888-1918). Unlike modern radio stations which transmit sound (an audio signal) on an uninterrupted carrier wave, early radio stations transmitted information by "radiotelegraphy". The transmitter was switched on and off to produce long or short periods of radio waves, spelling out text messages in Morse code. Therefore, early radio receivers had only to distinguish between the presence or absence of a radio signal. The device that performed this function in the receiver circuit was called a "detector". A variety of different detector devices, such as the coherer, electrolytic detector, magnetic detector and the crystal detector were used during the wireless telegraphy era until superseded by vacuum tube technology.
History of the transistor
The first patent for the field-effect transistor principle was filed in Canada by Austrian-Hungarian physicist Julius Edgar Lilienfeld on October 22, 1925, but Lilienfeld published no research articles about his devices, and his work was ignored by industry. In 1934 German physicist Dr. Oskar Heil patented another field-effect transistor. There is no direct evidence that these devices were built, but later work in the 1990s show that one of Lilienfeld's designs worked as described and gave substantial gain. Legal papers from the Bell Labs patent show that William Shockley and a co-worker at Bell Labs, Gerald Pearson, had built operational versions from Lilienfeld's patents, yet they never referenced this work in any of their later research papers or historical articles.
The Bell Labs work on the transistor emerged from war-time efforts to produce extremely pure germanium "crystal" mixer diodes, used in radar units as a frequency mixer element in microwave radar receivers. A parallel project on germanium diodes at Purdue University succeeded in producing the good-quality germanium semiconducting crystals that were used at Bell Labs. Early tube-based circuits did not switch fast enough for this role, leading the Bell team to use solid state diodes instead.
Texas Instruments
In January 1954 Morris Tanenbaum at Bell Labs created the first workable silicon transistor. This work was reported in the spring of 1954, at the IRE off-the-record conference on Solid State Devices, and was later published in the Journal of Applied Physics. Working independently in April 1954, Gordon Teal at TI created the first commercial silicon transistor and tested it on April 14, 1954. On May 10, 1954, at the Institute of Radio Engineers (IRE) National Conference on Airborne Electronics in Dayton, OH,Teal presented a paper: "Some Recent Developments in Silicon and Germanium Materials and Devices,".
Invention of the integrated circuit
The invention of the transistor in 1947 led to the expectation of a new technological revolution. Fiction writers and journalists heralded the imminent appearance of "intelligent machines" and robotization of all aspects of life. Although transistors did reduce the size and power consumption, they could not solve the problem of reliability of complex electronic devices. On the contrary, dense packing of components in small devices hindered their repair. While the reliability of discrete components was brought to the theoretical limit in the 1950s, there was no improvement in the connections between the components.
Science and technology in the United States
An American invention that was barely noticed in 1947 went on to usher in the Information Age. In that year John Bardeen, William Shockley, and Walter Brattain of Bell Laboratories drew upon highly sophisticated principles of quantum physics to invent the transistor, a small substitute for the bulky vacuum tube. This, and a device invented 10 years later, the integrated circuit, made it possible to package enormous amounts of electronics into tiny containers. As a result, book-sized computers of today can outperform room-sized computers of the 1960s, and there has been a revolution in the way people live – in how they work, study, conduct business, and engage in research.
Transistor
The first high-frequency transistor was the surface-barrier germanium transistor developed by Philco in 1953, capable of operating up to . These were made by etching depressions into an N-type germanium base from both sides with jets of Indium(III) sulfate until it was a few ten-thousandths of an inch thick. Indium electroplated into the depressions formed the collector and emitter.
Invention of radio
The Haven Hotel station and Wireless Telegraph Mast was where much of Marconi's research work on wireless telegraphy was carried out after 1898. In 1899, he transmitted messages across the English Channel. Also in 1899, Marconi delivered ""Wireless Telegraphy"" to the Institution of Electrical Engineers. In addition, in 1899, W. H. Preece delivered "Aetheric Telegraphy", stating that the experimental stage in wireless telegraphy had been passed in 1894 and inventors were then entering the commercial stage. Preece, continuing in the lecture, details the work of Marconi and other British inventors. In April 1899, Marconi's experiments were repeated for the first time in the United States, by Jerome Green at the University of Notre Dame. In October, 1899, the progress of the yachts in the international race between the Columbia and Shamrock was successfully reported by aerial telegraphy, as many as 4,000 words having been (as is said) despatched from the two ship stations to the shore stations. Immediately afterward the apparatus was placed by request at the service of the United States Navy Board, and some highly interesting experiments followed under Marconi's personal supervision. The Marconi Company was renamed Marconi's Wireless Telegraph Company in 1900.
In 1901, Marconi claimed to have received daytime transatlantic radio frequency signals at a wavelength of 366 metres (820 kHz). Marconi established a wireless transmitting station at Marconi House, Rosslare Strand, Co. Wexford in 1901 to act as a link between Poldhu in Cornwall and Clifden in Co. Galway. His announcement on 12 December 1901, using a kite-supported antenna for reception, stated that the message was received at Signal Hill in St John's, Newfoundland (now part of Canada) via signals transmitted by the company's new high-power station at Poldhu, Cornwall. The message received had been prearranged and was known to Marconi, consisting of the Morse letter 'S' - three dots. Bradford has recently contested the reported success, however, based on theoretical work as well as a reenactment of the experiment. It is now well known that long-distance transmission at a wavelength of 366 meters is not possible during the daytime, because the skywave is heavily absorbed by the ionosphere. It is possible that what was heard was only random atmospheric noise, which was mistaken for a signal, or that Marconi may have heard a shortwave harmonic of the signal. The distance between the two points was about .
Audio power amplifier
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.
History of the transistor
Masaru Ibuka, co-founder of the Japanese firm Sony, was visiting the United States when Bell Labs announced the availability of manufacturing licenses, including detailed instructions on how to manufacture junction transistors. Ibuka obtained special permission from the Japanese Ministry of Finance to pay the $50,000 license fee, and in 1955 the company introduced their own five-transistor "coatpocket" radio, the TR-55, under the new brand name Sony. This product was soon followed by more ambitious designs, but it is generally regarded as marking the commencement of Sony's growth into a manufacturing superpower.
Hearing aid
The first electrical hearing aid used the carbon microphone of the telephone and was introduced in 1896. The vacuum tube made electronic amplification possible, but early versions of amplified hearing aids were too heavy to carry around. Miniaturization of vacuum tubes lead to portable models, and after World War II, wearable models using miniature tubes. The transistor invented in 1948 was well suited to the hearing aid application due to low power and small size; hearing aids were an early adopter of transistors. The development of integrated circuits allowed further improvement of the capabilities of wearable aids, including implementation of digital signal processing techniques and programmability for the individual user's needs.
Morris Tanenbaum
When Morris Tanenbaum joined the chemistry department at Bell Laboratories in 1952, Bell was a hotbed for semiconductor research. The first transistor had been created there in December 1947 by William Bradford Shockley, John Bardeen and Walter Houser Brattain. Their point-contact transistor, built of germanium, was announced at a press conference in New York City on June 30, 1948.
Invention of radio
In the mid 1890s, building on techniques physicists were using to study electromagnetic waves, Guglielmo Marconi developed the first apparatus for long distance radio communication. On 23 December 1900, the Canadian inventor Reginald A. Fessenden became the first person to send audio (wireless telephony) by means of electromagnetic waves, successfully transmitting over a distance of about 1.6 kilometers, and six years later on Christmas Eve 1906 he became the first person to make a public radio broadcast.
American automobile industry in the 1950s
Until mid-decade, all radios in automobiles used vacuum tubes, but on April 28, 1955, Chrysler and Philco announced the development and production of the first all-transistor radio for an automobile. Dubbed the Mopar model 914HR, it was jointly developed by Chrysler and Philco and offered as a $150 option for 1956 Imperial and Chrysler car models. Philco manufactured the radio exclusively for Chrysler at its Sandusky, Ohio plant. A few years earlier in 1952, Blaupunkt had been the first company to offer FM radio for automobiles, although AM radio still dominated for years to come. Beginning in 1955, Chrysler offered a small phonograph called the Highway Hi-Fi in its luxury cars, which played proprietary seven-inch records. It proved unpopular and was soon discontinued.
Chrysler Imperial
In April 1955 Chrysler and Philco announced the development and production of the world’s first all-transistor car radio. The radio, Mopar model 914HR, was a $150.00 "option" on 1956 Imperial automobile models. Philco began manufacturing the all-transistor car radio for Chrysler in the fall of 1955 at its Sandusky, Ohio plant.
History of the transistor
A transistor is a semiconductor device with at least three terminals for connection to an electric circuit. The vacuum-tube 
triode, also called a (thermionic) valve, was the transistor's precursor, introduced in 1907.
Grimeton Radio Station
The Alexanderson alternator technology was becoming obsolete even as it was installed. Vacuum tube electronic oscillator transmitters, which used the triode vacuum tube invented by Lee De Forest in 1907, replaced most pre-electronic transmitters in the early 1920s. However the large capital investment in an alternator transmitter caused owners to keep these huge behemoths in use long after they were technologically obsolete. By the 1930s transatlantic communication had switched to short waves, and vacuum tube shortwave transmitters were installed in the main building, and a log periodic shortwave antenna on the roof. The Alexanderson alternator found a second use as a naval transmitter to communicate with submarines.
History of the Tesla coil
Although there is some disagreement over the role Tesla himself played in the invention of radio, sources agree on the importance of his circuit in early radio transmitters. From a modern perspective, most spark transmitters could be regarded as Tesla coils.
Radio receiver
Although it was invented in 1904 in the wireless telegraphy era, the crystal radio receiver could also rectify AM transmissions and served as a bridge to the broadcast era. In addition to being the main type used in commercial stations during the wireless telegraphy era, it was the first receiver to be used widely by the public. During the first two decades of the 20th century, as radio stations began to transmit in AM voice (radiotelephony) instead of radiotelegraphy, radio listening became a popular hobby, and the crystal was the simplest, cheapest detector. The millions of people who purchased or homemade these inexpensive reliable receivers created the mass listening audience for the first radio broadcasts, which began around 1920. By the late 1920s the crystal receiver was superseded by vacuum tube receivers and became commercially obsolete. However it continued to be used by youth and the poor until World War 2. Today these simple radio receivers are constructed by students as educational science projects.
Goldschmidt alternator
The Goldschmidt alternator or reflector alternator, invented in 1908 by German engineer Rudolph Goldschmidt, was a rotating machine which generated radio frequency alternating current and was used as a radio transmitter. Radio alternators like the Goldschmidt were some of the first continuous wave radio transmitters. Like the similar Alexanderson alternator, it was used briefly around World War I in a few high power longwave radio stations to transmit transoceanic radiotelegraphy traffic, until the 1920s when it was made obsolete by vacuum tube transmitters.
Invention of radio
Marconi was awarded a patent for radio with British patent No. 12,039, "Improvements in Transmitting Electrical Impulses and Signals and in Apparatus There-for". The complete specification was filed March 2, 1897. This was Marconi's initial patent for the radio, though it used various earlier techniques of various other experimenters and resembled the instrument demonstrated by others (including Popov). During this time spark-gap wireless telegraphy was widely researched. In July, 1896, Marconi got his invention and new method of telegraphy to the attention of Preece, then engineer-in-chief to the British Government Telegraph Service, who had for the previous twelve years interested himself in the development of wireless telegraphy by the inductive-conductive method. On June 4, 1897, he delivered "Signalling through Space without Wires". Preece devoted considerable time to exhibiting and explaining the Marconi apparatus at the Royal Institution in London, stating that Marconi invented a new relay which had high sensitiveness and delicacy.
Radio receiver
The invention of the transistor in 1947 revolutionized radio technology, making truly portable receivers possible, beginning with transistor radios in the late 1950s. Although portable vacuum tube radios were made, tubes were bulky and inefficient, consuming large amounts of power and requiring several large batteries to produce the filament and plate voltage. Transistors did not require a heated filament, reducing power consumption, and were smaller and much less fragile than vacuum tubes.
Regency TR-1
In May 1954, Texas Instruments had designed and built a prototype transistor radio and was looking for an established radio manufacturer to develop and market a radio using their transistors. No major radio maker, including RCA, Philco, and Emerson, was interested. The President of I.D.E.A. at the time, Ed Tudor, jumped at the opportunity to manufacture the TR-1, predicting sales of the transistor radios would be "20 million radios in three years." The Regency Division of I.D.E.A announced the TR-1 on October 18, 1954, and put it on sale in November 1954. It was the first practical transistor radio made in significant numbers.
Radio receiver
The crystal radio used a cat's whisker detector, invented by Harrison H. C. Dunwoody and Greenleaf Whittier Pickard in 1904, to extract the audio from the radio frequency signal. It consisted of a mineral crystal, usually galena, which was lightly touched by a fine springy wire (the "cat whisker") on an adjustable arm. The resulting crude semiconductor junction functioned as a Schottky barrier diode, conducting in only one direction. Only particular sites on the crystal surface worked as detector junctions, and the junction could be disrupted by the slightest vibration. So a usable site was found by trial and error before each use; the operator would drag the cat's whisker across the crystal until the radio began functioning. Frederick Seitz, a later semiconductor researcher, wrote:
Such variability, bordering on what seemed the mystical, plagued the early history of crystal detectors and caused many of the vacuum tube experts of a later generation to regard the art of crystal rectification as being close to disreputable.
The crystal radio was unamplified and ran off the power of the radio waves received from the radio station, so it had to be listened to with earphones; it could not drive a loudspeaker. It required a long wire antenna, and its sensitivity depended on how large the antenna was. During the wireless era it was used in commercial and military longwave stations with huge antennas to receive long distance radiotelegraphy traffic, even including transatlantic traffic. However, when used to receive broadcast stations a typical home crystal set had a more limited range of about 25 miles. In sophisticated crystal radios the "loose coupler" inductively coupled tuned circuit was used to increase the Q. However it still had poor selectivity compared to modern receivers.
Repeater
This is used to extend the range of coverage of a radio signal. The history of radio relay repeaters began in 1898 from the publication by Johann Mattausch in Austrian Journal Zeitschrift für Electrotechnik (v. 16,
35 - 36). But his proposal "Translator" was primitive and not suitable for use. The first relay system with radio repeaters, which really functioned, was that invented in 1899 by Emile Guarini-Foresio.
Herbert Mataré
At the same time as the American researchers and independently, the German researchers Mataré and Heinrich Welker developed the first operational "French transistor" at Compagnie des Freins & Signaux Westinghouse in Aulnay-sous-Bois near Paris during the years 1945 to 1948. They filed their first transistor patent application on 13 August 1948. On 18 May 1949, this European invention coined as the "Le Transistron" was presented to the public.
Radio hat
Battery-operated portable radios had been available for many years, but Hoeflich hoped a radio with innovative packaging and a publicity campaign could be a runaway success. The transistor had just been invented, but was still an expensive laboratory curiosity; the first pocket transistor radio was still 5 years away. This radio would have to use the existing vacuum tube technology and the tubes would be a prominent design feature. The loop antenna and the tuning knob were also visible. The hat was available in eight colors: Lipstick Red, Tangerine, Flamingo, Canary Yellow, Chartreuse, Blush Pink, Rose Pink and Tan.
Transistor radio
There are many claimants to the title of the first company to produce practical transistor radios, often incorrectly attributed to Sony (originally Tokyo Telecommunications Engineering Corporation). Texas Instruments had demonstrated all-transistor AM (amplitude modulation) radios as early as May 25, 1954, but their performance was well below that of equivalent vacuum tube models. A workable all-transistor radio was demonstrated in August 1953 at the Düsseldorf Radio Fair by the German firm Intermetall. It was built with four of Intermetall's hand-made transistors, based upon the 1948 invention of the "Transistron"-germanium point-contact transistor by Herbert Mataré and Heinrich Welker. However, as with the early Texas Instruments units (and others) only prototypes were ever built; it was never put into commercial production. RCA had demonstrated a prototype transistor radio as early as 1952, and it is likely that they and the other radio makers were planning transistor radios of their own, but Texas Instruments and Regency Division of I.D.E.A., were the first to offer a production model starting in October 1954.
The use of transistors instead of vacuum tubes as the amplifier elements meant that the device was much smaller, required far less power to operate than a tube radio, and was more shock-resistant. Since the transistor base draws current, its input impedance is low in contrast to the high input impedance of the vacuum tubes. It also allowed "instant-on" operation, since there were no filaments to heat up. The typical portable tube radio of the fifties was about the size and weight of a lunchbox, and contained several heavy, non-rechargeable batteries— one or more so-called "A" batteries to heat the tube filaments and a large 45- to 90-volt "B" battery to power the signal circuits. By comparison, the transistor radio could fit in a pocket and weighed half a pound or less, and was powered by standard flashlight batteries or a single compact 9-volt battery. The now-familiar 9-volt battery was introduced for powering transistor radios.