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The History of Electronics Inventors and their Inventions Physicist Isaac Newton wrote, “If I have seen further it is by standing on the shoulders of Giants”. The field of electronics is no different; we could not have the technology we have today without the contributions of thousands of brilliant people. This series of articles is about them. Part 2: by Dr David Maddison T he first article of this three-part series, published last month, listed significant electronics-­ related inventions of individual inventors born before 1848. This part will cover all the individual inventors (that we can fit) born from 1848 onward, while the third part next month will discuss significant inventions credited to companies and other organisations. Inventors by date of birth (1848 onward): Shelford Bidwell photocells 1848-1909 Experimented with selenium photocells in the 1870s, and in 1880, reported how he also duplicated the “photophone” experiment of Alexander Graham Bell (siliconchip.au/link/ abnc). In another experiment, he used a selenium cell to scan an image and transmit it to another device via wires, which burned the reproduced image onto paper. He reported the results of his “Tele-­ Photography” in 1881 (siliconchip.au/ link/abnd). He was the first to use a photocell to scan an image (Bain and Bakewell did not; see last month). He also invented a device that could scan an original document without 18 Silicon Chip redrawing it on special media, analogous to a modern fax machine. In 1908, he published “Telegraphic Photography and Electric Vision” (siliconchip.au/link/abne), on transmitting motion video (ie, TV) and the large amount of data involved. Chichester A. Bell tape recorder 1848-1924 Bell and Sumner Tainter (18541940) received US patent 341,214 in 1886 for a recording and playback device where sound was recorded on a wax-coated paper strip in a reel-toreel arrangement. It was the earliest tape recorder, but was considered inferior to Edison’s wax cylinder for recording and playback and was not commercially released. Sir John Ambrose Fleming 1849-1945 thermionic valve, trans-Atlantic transmission Invented the first thermionic valve, otherwise known as a “vacuum tube”, in 1904 (see Fig.29). Fleming called them oscillation valves “for the rectification of high-frequency electric oscillations as used in wireless telegraphy”. They were diodes, the simplest type of valve. Fleming’s valve is considered the beginning of electronics because it was the first active electronic component. As radio detectors, Fleming’s valves were not more sensitive than crystal detectors. However, they did not need Fig.29: Fleming’s first vacuum tube diodes from 1904. Source: https://w.wiki/7DAU Australia's electronics magazine siliconchip.com.au constant adjustment for use on ships due to the movement like crystals did. In 1899, Fleming, under contract from Marconi, designed the first highpower radio transmitter, much larger than the 200-400W transmitters used by Marconi. It was a spark-gap transmitter powered by a 25kW alternator and it performed the first trans-­ Atlantic transmission in 1901, over 3500km, which was credited to Marconi despite Fleming’s involvement. Charles Fritts 1850-1903 solid-state solar cells He made the world’s first solid-state solar cells in 1883 with selenium and a thin layer of gold. They had an efficiency of 1%, making them too expensive and inefficient for generating power, but they were used as light sensors for cameras and in other applications into the 1960s. Oliver Heaviside mathematical equations, E region etc 1850-1925 Reformulated and simplified Maxwell’s equations to make the Maxwell-­ Heaviside equations and put them in their modern form. He also invented the Heaviside step function to calculate the current drawn when an electrical circuit is switched on, and developed transmission line theory (or telegraphers’ equations). The latter increased the transmission rate of the trans-Atlantic telegraph cable ten times, to one character per minute. He discovered that telephone line transmissions could be improved by a series inductance in the cable. He and Arthur Edwin Kennelly (1861-1939) independently predicted the presence of the Heaviside layer, Kennelly-­ Heaviside layer or E region, part of the ionosphere that reflects medium-­ frequency waves. William Edward Sawyer electricity distribution 1850-1883 Sawyer worked on telegraphy and electric lighting. With Albon Man, he founded the Electro-Dynamic Light Company (1878-1882), later purchased by Westinghouse, to provide lighting and distribute electricity into cities. His lighting system contained a safety switch and a current regulator. His company had patents dated 1877 and 1878 for incandescent lights, predating Edison. Sawyer’s lights were not long-lasting, a problem he never solved. Karl Ferdinand Braun 1850-1918 cathode ray tube (CRT), oscilloscope etc He discovered the rectifying properties of a metal-semiconductor junction (schottky diode) in 1874, using mercury as the metal and copper sulfide or iron sulfide as the semiconductor. He also invented the cathode ray tube and the oscilloscope in 1897. He worked on wireless telegraphy and invented a crystal detector in 1898, among other contributions. In 1905, he devised the phased array antenna. Edward Weston 1850-1936 Weston Cell, Constantan & Manganin alloys Invented the Weston Cell in 1893, a highly-stable electrochemical cell used as a voltage reference. It was the international standard for EMF from 1911-1990. He invented the alloy Constantan in 1887, which has a low variation in resistivity with temperature, used in thermocouples, and Manganin in 1892, with almost no variation in resistivity with temperature, used in precision resistors. In 1888, he founded the Weston Electrical Instrument Corporation, which became famous for the wide variety of high-quality electric meters it manufactured. Sir Oliver Joseph Lodge moving-coil loudspeaker etc 1851-1940 Lodge identified electromagnetic radiation independent of Hertz. He also made an improved Hertzian wave detector based on metal filings in a tube he named a “coherer”, based on Branly’s earlier work (see last month). Under the influence of a radio signal, the conductivity between the two electrodes would change. The device had to be regularly tapped to restore its sensitivity. It was used until 1907, when Marconi’s crystal detector replaced it. He also invented the moving-­coil loudspeaker in 1898. In 1898, he invented and patented “syntonic tuning” to tune radio equipment to specific frequencies, causing a patent dispute with Marconi. He developed a form of electric spark ignition for internal combustion engines. Emile Berliner 1851-1929 microphone, Berliner Gramaphone Record Developed an improved type of telephone transmitter (microphone); his patent was acquired by the Bell Telephone Company. It was contested by Thomas Edison, who won the case. There were many expensive and complicated court cases in the USA in the 1870s and 1880s contesting the invention of the telephone; see https://w. wiki/7DYJ In 1887 and 1888, Berliner received US patents 372,786 & 382,790 for the “Berliner Gramophone Record”. They were flat discs, like the records we know today, although the Berliner records were only 18cm in diameter, played two minutes per side and rotated between 60RPM and 75RPM. They competed against wax cylinder recordings. There is a project to put about 18,000 Berliner recordings on Flickr: siliconchip.au/link/abpa Leonardo Torres y Quevedo 1852-1936 “Telekino” remote control, El Ajedrecista game Quevedo demonstrated a remote control he invented in 1903, called the “Telekino” (Fig.30). It was remarkably advanced for the time and was the second remote control invented after Tesla’s in 1898. 19 different commands could be sent, with the command Karl Ferdinand Braun was a founder of Telefunken. Source: www. cathodique.net/ FBraun.jpg Fig.30 (right): the Telekino receiver in the Torres Quevedo Museum in Madrid, Spain. Source: https://w. wiki/7DAV siliconchip.com.au Australia's electronics magazine November 2023  19 sequence recorded. He tested it with dirigibles in 1901. In 1905, he demonstrated the device with a three-wheeled vehicle, and in 1906, a boat with people onboard. The work was abandoned due to a lack of money. He also invented what was arguably the first computer game. It was called “El Ajedrecista” and could play certain chess moves (see Fig.31). Mechanical arms moved pieces while sensors detected the opponent’s moves. It still works today and can be seen at the Torres Quevedo Museum in Madrid. Temistocle Calzecchi-Onesti experiments leading to the coherer Fig.31: the remarkable El Ajedrecista chess-playing machine. Source: www. torresquevedo.org/LTQ10/images/ PrimerAjedrecista.jpg (CC BY-SA 3.0). 1853-1922 Conducted experiments from 1884 on the electrical conductivity of tubes of metal filings and how they were affected by various electrical influences. This led to Branly’s invention of the coherer (see Lodge’s entry on page 19). Heike Kamerlingh Onnes superconductivity 1853-1926 He discovered superconductivity in 1911 (the loss of all electrical resistance of some materials at certain low temperatures). It is used to generate powerful magnetic fields in machines like MRI scanners. High-temperature superconductors with less stringent cooling requirements are currently being developed. Jonas Wenström three-phase electrical system Fig.32: the operation of a Hall effect IC. Original source: www.ablic. com/en/semicon/products/sensor/ magnetism-sensor-ic/intro/ 1855-1893 Received a Swedish patent for a three-phase electrical system in 1890. He developed it independently of Mikhail Dolivo-Dobrovolsky (see his entry on page 22). Edwin Herbert Hall Hall effect 1855-1938 He discovered what is now known as the Hall effect in 1879, the basis of modern magnetic field detectors and Hall thrusters on spacecraft. It explains that a voltage is produced at right angles to a current flow in a conductor with a magnetic field perpendicular to the current flow – see Fig.32. Paul-Jacques Curie piezoelectricity Fig.33: Hertz’s 1887 spark-gap transmitter, with an induction coil, dipole antenna, capacitance (C) at the ends, a spark gap (S) and resonant loop antenna receiver with a spark micrometer (M) to measure signal strength. It operated at around 50MHz. Source: https://w. wiki/7DAW (CC-BY-SA-3.0). 20 Silicon Chip 1855-1941 With his brother Pierre Curie (18591906), discovered piezoelectricity (used for guitar pickups etc) in 1880. They also studied pyroelectricity. Nikola Tesla 1856-1943 polyphase electrical system, Tesla coil etc Tesla was a prolific inventor and genius. He developed the polyphase electrical system (AC power with Australia's electronics magazine more than one phase) and associated induction motors, licensed by Westinghouse in 1888. From 1890, he tried to develop a wireless lighting system using Geissler tubes powered by a Tesla coil he invented in 1891. He was photographed at his Colorado Springs facility in 1899 with the “magnifying transmitter” Tesla coil (done using double-exposure; see the lead image). It produced 12MV 150kHz arcs up to 41m long with an input power of 300kW. In 1893, he consulted on the design of a Niagara Falls hydroelectric power station. In 1898, he developed the first wireless radio remote control for a boat, a concept he called teleautomatics. In 1906, he demonstrated a bladeless turbine for a power station, which spun at 16,000RPM and produced 150kW. The unit of magnetic flux intensity, the tesla (T), is named after him. Sir Joseph John Thomson acoustic waveguide 1856-1940 Contributed to atomic physics. In 1893, he proposed the acoustic waveguide, and in 1894, Oliver Lodge experimentally verified it. In 1897, Thomson suggested the existence of the electron. He also conducted experiments with cathode rays. Heinrich Rudolph Hertz spark gap transmitter, radio waves 1857-1894 Hertz proved the existence of radio waves, first predicted by Maxwell’s equations, from 1887 onward. He demonstrated properties such as polarisation, reflection and standing waves. In 1887, he also built the first spark gap transmitter (Fig.33). The unit of frequency, the hertz (Hz), is named after him. William Stanley Jr 1858-1916 AC transformer and complete AC system Built the first practical AC transformer in 1885 based on the prototype of Gibbs and Gaulard; see US patent 349,611. In 1886, he demonstrated a complete AC system with generators, transformers and high-voltage transmission lines in Great Barrington, Massachusetts, lighting offices and stores. Sir Jagadish Chandra Bose 1858-1937 millimetre waves, microwave components etc He produced millimetre (5mm wavelength) 60GHz electromagnetic waves in 1894 because they were a more convenient size to work with in his small laboratory – see Fig.34. In 1895, he demonstrated how siliconchip.com.au Fig.34: 60GHz microwave apparatus by Jagadish Bose. The galvanometer and battery are modern. The transmitter on the right generates microwaves from sparks between tiny metal balls. Above the galvanometer is a galena point-contact detector inside a horn antenna. Source: https://w.wiki/7DAY (CC-SA-3.0). millimetre waves could go through the human body and walls, achieving a range of 23m. Bose was not interested in patenting or commercialising his amazing work, although he was persuaded to patent a metal-­ semiconductor diode in 1901, awarded in 1904 (US patent 755,840). He developed a galena semiconductor crystal microwave detector and many other now-familiar microwave components, such as waveguides, horn antennas, dielectric lenses and polarisers. Much of his equipment can be seen at the Bose Institute Museum in Kolkata, India (www.jcbose.ac.in/ museum). Nobel laureate Sir Neville Mott said that Bose was 60 years ahead of his time and that he had anticipated p-type and n-type semiconductors. One of his concepts from a paper he wrote in 1897 was used in the 1.3mm multibeam receiver of the National Radio Astronomy Observatory (NRAO) 12m telescope in Tuscon, Arizona. Friedrich August Haselwander 1859-1932 electric arc lamp Invented an electric arc lamp in 1880, and in 1887 invented and put into service a synchronous threephase generator in Europe (Fig.35). It developed about 2.8kW at 960RPM and 32Hz. Aleksandr Popov lightning detector (radio receiver) 1859-1906 Popov built a wireless lightning detector in 1895 (see Fig.36), one of the first radio receivers, and in 1896 transmitted radio signals over 250m. Some of his work was based on the findings of Sir Oliver Joseph Lodge. In 1898, he performed ship-to-shore communication using wireless telegraphy over 10km, and in 1899, 48km. In ex-USSR countries, the 7th of May is celebrated as Radio Day, the day Popov first demonstrated his lightning detector. Herman Hollerith punch(ed) cards 1860-1929 Developed punched cards for data storage and analysis, used in the 1890 US Census. These evolved into IBM punched cards, used as late as the early 1980s. See our January 2023 article on Computer Memory for more on punched/punch cards (siliconchip.au/ Series/393). Ottó Titusz Bláthy 1860-1939 modern transformers, voltage regulator etc Sir Jagadish Bose demonstrating the horn antenna. Source: https://w. wiki/7DuL Fig.36: Alexander Stepanovich Popov’s 1895 “coherer receiver”, one of the first radio receivers, designed to detect lightning strikes. Key: A) antenna, B) bell, C) coherer (detector), E) electromagnet, G) ground, L) chokes for noise immunity, R) relay, V) battery. Source: https://w. wiki/7DAa siliconchip.com.au Fig.35: Haselwander’s three-phase generator with stationary ring armature and four-pole rotor, as displayed in 1891 at the International Electrotechnical Exhibition in Frankfurt. Source: https://w. wiki/7DAZ Australia's electronics magazine Bláthy, Károly Zipernowsky (18531942) and Miksa Déri (1854-1938) applied for a patent for the first modern transformers in 1885, which were much more efficient than the designs of Gaulard or Gibbs. The trio also designed the first power station with AC generators “to power a parallel-­ connected common electrical network”. Bláthy also invented the voltage regulator, AC watt-hour meter (1889), motor capacitor for single-phase AC motors and turbo generator for steam power plants. Paul Julius Gottlieb Nipkow Nipkow disc 1860-1940 Invented the Nipkow disc in 1883. It was a disc with a spiral pattern of holes to divide a picture into a linear series of points to enable opto-electronic November 2023  21 Paul Gottlieb Nipkow is considered to be one of the fathers of television. Source: https://w. wiki/7DuZ imaging of an object. There was little interest at the time. It became the basis of the first electro-­optical television systems in the 1920s-30s (see our articles on Display Technologies in the September & October 2022 issues - siliconchip.au/ Series/387). Peter Cooper Hewitt 1861-1921 mercury vapour lamp, mercury arc rectifier He invented the mercury vapour lamp in 1901, the predecessor of the fluorescent lamp. In 1902, he invented the mercury arc rectifier, the first commercially available non-mechanical rectifier. In 1916, he was involved in developing the Hewitt-Sperry Automatic Airplane, the predecessor of the cruise missile. Mikhail Dolivo-Dobrovolsky asynchronous three-phase motor 1862-1919 Invented an asynchronous threephase motor in 1888, which had low torque at low speeds. This problem was solved with a variation of that motor, the slip-ring motor, with high torque at low speeds in 1891. He also developed the delta-wye transformer for three-phase distribution systems in that year. television would be solved by electronic systems with CRTs at both ends. Walther Hermann Nernst Nernst (incandescent) lamp 1864-1941 Invented the Nernst lamp (Fig.37) in 1897 as an improvement to the incandescent lamp. The way it works is very interesting. An element heats a ceramic rod made of zirconium oxide and yttrium oxide. The rod’s resistance decreases as it heats up and the heating element is turned off. A current sustains the glowing ceramic rod due to ohmic heating. It can operate in the air, as the ceramic rod will not degrade like a metal filament. They are obsolete as a visible light source but are still used as an infrared light source in spectroscopy, as they emit infrared over a wide range of wavelengths. See the video titled “The Nernst Lamp” at https:// youtu.be/1vCQySb6ulA Charles Proteus Steinmetz Steinmetz’s equation 1865-1923 He contributed to AC hysteresis theory from 1890 and solved practical problems with heat build-up in AC motors. This resulted in him building a powerful motor for Otis Elevators to reach higher floors. His work led to Steinmetz’s equation for calculating losses in magnetic core materials, published in 1892 (see the PDF at siliconchip.au/link/abnf). 22 Silicon Chip 1866-1932 He first transmitted speech by radio in 1900 and made the first twoway radiotelegraphic communication across the Atlantic in 1906. He invented an electroacoustic transducer called the Fessenden oscillator in 1912, and in 1914, it detected icebergs 3km away. It was also used for underwater telephony and depth sounding. For more information on that, see our June 2019 article on Bathymetry (siliconchip.au/Article/11664). Marie Curie 1867-1934 mobile X-ray machine Invented the mobile X-ray machine in around 1915, powered by a dynamo. Henri Abraham 1868-1943 astable multivibrator He and Eugene Bloch (1878-1944) invented the astable multivibrator. The work was done during WW1 but published in 1919. He made the first measurements of the speed of electromagnetic propagation between 19111914 and developed the first French triode valve. Worked in telephone technology and radios. In 1890, he started work on a mathematical analysis of telephone links for American Bell Telephone Co. In 1900, he developed “selective four-circuit tuning” for radios to improve their selectivity and reduce noise. Lenard began investigations of cathode rays in 1888 and developed a modified Crookes tube with what was to become known as a “Lenard window”, a thin aluminium window that made it possible to study the radiation from outside the tube. Boris Lvovich Rosing early television 1869-1933 Fig.37: a Nernst lamp, an early form of incandescent light. Source: https://w.wiki/7DAb He started considering ideas of what we now know as television in 1897, but he called it the “electric telescope”. His approach for the receiver was purely electronic, using a CRT, unlike other ideas for television around that time that were mainly mechanical. By 1902, he made a device that could draw a basic figure on a CRT. Instead of a slow-reacting selenium cell detecting light for the camera, he used a fast-reacting photocell onto which the image was projected by a rotating mirror system. He obtained patents for his invention in 1907 and 1911. It was presented Australia's electronics magazine siliconchip.com.au 1863-1930 Alan Archibald Campbell-Swinton experimented with cathode ray tubes (CRTs) in 1903 for transmitting television images. Prompted by Shelford Bidwell, on the 18th of June, 1908, his letter in Nature entitled “Distant Electric Vision” (siliconchip.au/link/abpb) said the problems of mechanical radio, sonar etc 1869-1943 telephone links, selective four-circuit tuning 1862-1947 Lenard window (aluminium) for Crookes tube transmitting television images Reginald Aubrey Fessenden John Stone Stone Philipp Lenard Alan Campbell-Swinton He worked on AC circuit theory and analysis, which he greatly simplified from previous methods, announcing his findings in 1893. He also investigated AC transient theory and other transient phenomena, such as lightning bolts. Fig.38: Valdemar Poulsen’s magnetic wire recorder, invented in 1898. Source: https://w.wiki/7DAd (CC-BYSA-2.5). in Scientific American, 1st of April, 1911: siliconchip.au/link/abng Valdemar Poulsen magnetic audio recordings 1869-1942 Successfully implemented the first means to magnetically record audio in 1898 by magnetising wire along its length (Fig.38). There was no amplification, so the recording was faint but audible with headphones. The device was called the Telegraphone and had limited commercial success due to its low volume and complexity. With his assistant, Peder Oluf Pedersen, he developed other recording devices using tape and discs. In 1903, he also invented the Poulsen Arc Transmitter (Fig.39), widely used as a radio transmitter in the early 1920s before vacuum tubes were developed. Arthur Korn fax machines 1870-1945 Korn pioneered the modern fax machine, which he used to transmit photographs. He used light-sensitive selenium cells in his “phototelautograph” or “Bildetelegraph”. In 1906, he sent a photo of Crown Prince Wilhelm over 1800km via the telegraph network. In 1913, he transmitted a movie recording, although the specifics are unclear. We assume it was a frame-byframe transmission. In 1923, German police used Korn’s system to transmit photos and fingerprints. Paul Langevin ultrasound transducer Fig.39: a 1919 Poulsen arc transmitter from a US Navy radio station with a continuous power rating of 500kW (1MW short-term). Source: https://w.wiki/7DAe making tungsten ductile, allowing it to be drawn into filaments for light globes. The globes were sold by General Electric from 1911. Lee De Forest 1873-1961 three-element triode, recording audio Invented a three-element triode thermionic tube in 1906, the “grid Audion” (Fig.40), for use as an amplifier and an oscillator. This invention is regarded as the start of the Electronic Age. In 1919, he patented the DeForest Phonofilm system for optically recording audio waveforms onto movie films. Guglielmo Marconi 1874-1937 wireless transmission, spark gap transmitter etc Guglielmo Giovanni Maria Marconi built a device to receive radio waves produced by lightning in 1894. That year, he also demonstrated wireless transmission to ring a bell across a room. He developed a spark gap transmitter and coherer receiver. A coherer was a glass tube with metal filings that radio waves caused to become closer together and therefore more conductive. In 1895, he designed a system that could transmit over 3km. By 1896, he had transmitted over 6km, then 16km. In 1899, he transmitted across the English Channel. In 1907, he established a commercial trans-Atlantic telegraph service. making tungsten ductile Just Sándor Frigyes tungsten filament light globe 1874-1937 Also known as Alexander Friedrich Just, he and Franjo Hanaman (18781941) were the first to invent an incandescent light globe with a tungsten filament in 1904. They were brittle due to the way they were made, although they lasted longer and were very efficient compared to carbon filaments. They licensed their patent to the Tungsram company (which also licensed Bródy’s patent for using krypton gas in globes in 1934). In 1904, they applied for a Hungarian patent and, in 1905, applied for US Patent 1,018,502. The tungsten filament globe became practical with the invention of Coolidge’s fabrication method for tungsten filaments. Alexander M. Nicholson crystal oscillator unknown Invented the first crystal oscillator in 1917 using Rochelle salt, a piezoelectric material, and filed for US patent 2,212,845 in 1918. Walter Guyton Cady quartz crystal oscillator 1874-1974 He invented a quartz crystal oscillator in 1921 and realised that such devices could be used as frequency standards. He filed US patents in 1921 (1,472,583) and 1937 (2,170,318). Fig.40: an early grid Audion, invented in 1906, which many regard as indicating the start of the electronic age. Source: https://w.wiki/7DAf (GFDL-1.2). 1872-1946 Invented the first ultrasound device in 1917, the quartz sandwich transducer for submarine detection. William David Coolidge Marconi’s radios were important in rescuing survivors of the RMS Titanic (1912) and RMS Lusitania (1915). 1873-1975 Coolidge developed a method for siliconchip.com.au Australia's electronics magazine November 2023  23 Édouard Belin Bélinographe, image transmission 1876-1963 Invented the Bélinographe, which used a photocell to scan and transfer press photos (see Fig.41). It was developed in 1907 and first used commercially in 1913-1914 to transmit pictures over dedicated leased telephone lines. Later models could use ordinary telephone lines. In 1921, a version was used to transmit a photo by radio across the Atlantic. By 1926, RCA was using it to transmit Radiophotos. Miller Reese Hutchison 1876-1944 electronic hearing aid, tachometer, Klaxon He developed the first commercial electronic hearing aid in 1898 (going to market in 1899), with a carbon microphone he called the “Akoulallion”. In 1900, he developed a portable battery-­ powered device that he called the “Akouphone”, then the Acousticon 1 in 1902. For more details: siliconchip. au/link/abnl In 1908, Hutchison invented an electric tachometer for ships and the Klaxon in 1910. Robert Von Lieben triode with control grid 1878-1913 Lieben, with engineers Eugen Reisz and Siegmund Strauss, invented the gas-filled (low vacuum) triode with a control grid in 1910. It was the first thermionic valve designed for amplification rather than demodulation and was used as a telephone repeater. Ernst Alexanderson Alexanderson alternator 1878-1975 Ernst Frederick Werner Alexanderson invented the Alexanderson alternator in 1904. It produced radio waves more efficiently and with a narrower bandwidth than the spark-gap transmitters used until that time, and it could deliver them continuously at high power. Alexanderson alternators were used to transmit long-wave radio communications from shore stations from 1906 to the 1990s, although they were too big and heavy for most ships. The first commercial model would generate a frequency of 100kHz and had a power rating of 50kW. The last transmitter in regular use was Grimeton Radio Station in Sweden, which was used until 1996 and is occasionally used today (see page 17 of our March 2023 issue). Albert Einstein 1879-1955 theory of relativity, photoelectric effect Published his theory of relativity in 1905. Relativity must be considered in operating satellite navigation systems such as GPS and many other applications. He also explained the photoelectric effect in 1905, expanding on the work of Planck, which went on to be used in night-vision devices, among others. Alexander Behm echo sounding, Echolot 1880-1952 He invented echo sounding in 1912 to measure water depth and detect obstacles, obtaining a patent in 1913. In 1922, he produced the Echolot to measure water depth beneath a ship. Albert W. Hull dynatron vacuum tube, magnetron 1880-1966 Invented the dynatron vacuum tube in 1918 and the magnetron in 1920, which was used as an amplifier and low-frequency oscillator. The latter is still used in microwave ovens (albeit in a modified form; see the entry for Russell Harrison Varian on page 27). Louis Blattner 1881-1935 Blattnerphone Blattner, under license by Kurt Stille (1873-1957), produced a new audio recorder using steel tape instead of wire called the “Blattnerphone” in 1925. It was also based on the magnetic recorder of Valdemar Poulsen (see his entry on page 23). In 1933, the Marconi Company acquired the rights to the Blattnerphone and made an improved version called the Marconi-Stille recorder, which the BBC used from 1935 into the 1940s (Fig.42). Irving Langmuir vacuum pump improvements Improved the vacuum pump, which led to high-vacuum rectifiers and amplifier tubes. He, along with Lewi Tonks, also discovered that an inert gas improved the lifetime of incandescent globes. He also found that twisting a tungsten filament enhances efficiency. Fritz Plfeumer magnetic tape for sound recording Cpt Henry Joseph Round LEDs, vacuum tubes 24 Silicon Chip Australia's electronics magazine 1881-1966 He contributed to vacuum tube development and developed a triode around the same time as Lee de Forest. He discovered feedback in vacuum tubes independently of Alexander Meissner and Edwin Armstrong. He made the first report of what we now know to be a light emitting diode (LED), utilising ‘cat’s whisker’ detectors, the first type of semiconductor detector, made of silicon carbide and producing faint yellow light. field-effect transistor (FET) Fig.42: the Marconi-Stille tape recorder. Source: Birmingham Museums Trust – https://w.wiki/7Dup (CC-BY-SA-4.0). 1881-1945 He invented magnetic tape for sound recording in 1927 and received a patent for it in 1928. He used paper and iron oxide, with lacquer as an adhesive to bind the oxide to the paper. In 1932, he granted rights to this invention to AEG. They used it with the first practical tape recorder, the Magnetophon K1, demonstrated in 1935. Julius Edgar Lilienfeld Fig.41: the Bélinographe used a photocell to scan and transfer photos in 1907. Source: https://w.wiki/7DAk 1881-1957 1882-1963 Filed for US patent 1,745,175 in 1926, awarded in 1930, for the field-­ effect transistor (FET) but could never build a practical device because of the unavailability of high-purity semiconductor materials at the time. Max Dieckmann video camera tube “image dissector” 1882-1960 Dieckmann and his student Rudolf siliconchip.com.au Fig.43: an Armstrong or Meissner Oscillator. Original source: www.itwissen.info/en/Meissneroscillator-127183.html#gsc.tab=0 Hell (1901-2002) obtained a patent in 1927 (applied for 1925) for a video camera tube called the “image dissector”. However, Philo T. Farnsworth was the first to make it actually work (see his entry on page 28). Alexander Meissner 1883-1958 radio navigation systems, Meissner oscillator Invented the Telefeunken Kompass Sender in 1911, one of the earliest radio navigation systems, comprising a directional beacon used to navigate Zeppelin airships (see siliconchip.au/ link/abnm). In 1913, he discovered positive feedback as applied to vacuum tube amplifiers. He co-invented the oscillator in 1913 (independently with Edwin Armstrong, 1912) and received a patent in 1920. The Armstrong oscillator or Meissner oscillator (Fig.43) uses an inductor and capacitor to produce oscillation with a valve (or transistor in modern implementations) as the amplifier. Its frequency is determined by a resonant circuit, with oscillation maintained by a feedback process. Saul Dushman vacuum tube diodes 1883-1954 While at General Electric, he produced the first vacuum tube diodes in 1915, usable as rectifiers in power supplies. Edith Clarke Clarke (graphical) calculator 1883-1959 Filed US patent 1,552,113 for the Clarke Calculator (Fig.44) in 1921, awarded in 1925. It greatly simplified calculations for long transmission lines. It was a physically simple graphical calculator, which we assume was made out of cardboard or similar, but with some complex mathematics behind it. It also embodied a correct understanding of how inductance and siliconchip.com.au Fig.45: Burnie Lee Benbow’s “coiled-coil” tungsten lamp filament from his 1917 US patent. Fig.44: the Edith Clarke calculator from US patent 1,552,113. capacity are uniformly distributed in long transmission lines, contrary to assumptions made at the time. Burnie Lee Benbow 1885-1976 coiled-coil tungsten filaments Benbow invented “coiled-coil” tungsten filaments for incandescent lamps in 1917 (Fig.45), extending their life due to less tungsten evaporation. Although simple in principle, there were enormous practical difficulties to overcome in fabrication. Georges Rignoux transmitting still images physics. The schottky diode (with a metal/semiconductor junction) is named after him. Hidetsugu Yagi Yagi-Uda antenna 1886-1976 Published articles to the West on the Yagi-Uda antenna (Fig.46), which was invented by his assistant, Shintaro Uda (1896-1976) in 1926. It is a directional antenna of simple design, commonly used for TV antennas and also widely used by radio amateurs. ~1885-unknown Rignoux and A. Fournier of La Rochelle transmitted still images in Paris in 1909. They were updated every few seconds, using a sensor with an 8×8 matrix of photo-sensitive selenium cells. The resolution was enough to reproduce the English (or French) alphabet. Walter Han Schottky thermionic valve, schottky diodes etc 1886-1976 Invented the screen grid thermionic valve in 1915, co-invented the ribbon microphone and ribbon loudspeaker with Erwin Gerlach in 1924 and made many contributions to semiconductor Australia's electronics magazine Fig.46: the basic configuration of a 3-element Yagi-Uda antenna. November 2023  25 John Logie Baird television 1888-1946 He made the first television image in 1925 (see Fig.47). It was of a rotating head, made using a Nipkow disk with 30 vertical lines of resolution. In 1926, he produced the first commercial television. In 1927, he transmitted a television picture over 705km via a telephone line. In 1928, he transmitted a television image across the Atlantic and in 1929, the BBC transmitted the first television programs. In 1940, he started work on the first single-tube electronic colour television system, Telechrome, which was demonstrated in 1944. He also worked on Phonovision between 1926 and 1928 (more on that next month). Sir C. V. Raman Raman effect 1888-1970 Sir Chandrasekhara Venkata Raman and Sir Kariamanikkam Srinivasa Krishnan (1898-1961) discovered the Raman effect in 1928. It is a form of light scattering used for analysing substances. A Raman spectrometer was used on the Mars lander Perseverance. Vladimir Kosma Zworykin ~1888-1982 iconoscope (television camera tube) Filed for US patent 2,141,059 for the iconoscope in 1923 (awarded 1938). This was the first practical television camera tube and it was used for the 1936 Olympics. In Europe, it was replaced that year by the Super-­ Emitron and Superikonoskop. However, it remained in use in the United States until 1946, when it was replaced by the image orthicon tube. Edwin Howard Armstrong 1890-1954 positive feedback (“regeneration”), superhet He was interested in how vacuum tubes work; they were not understood when the triode or “Audion” was invented by Lee de Forest in 1906. As a student, Armstrong experimented with these tubes with Professor John Harold Morecroft. Armstrong made a breakthrough discovery in 1912 that positive feedback or “regeneration” with a triode could dramatically increase the amplification possible, allowing the use of a loudspeaker rather than headphones. He also discovered that an Audion with sufficient feedback could be used to generate a high-frequency signal for radio transmitters. A complicated 25-year legal battle ensued between him and de Forest about patent rights for these discoveries, but Armstrong retains credit. 26 Silicon Chip In 1918, he invented the supersonic heterodyne or superhet circuit, which enabled radio receivers to be more selective and sensitive. That invention was also subject to legal disputation with Lucien Lévy of France, with most claims awarded to Lévy. He developed wideband FM radio and first presented a paper on the subject in 1935, published in 1936. Imre Bródy krypton light globes 1891-1944 Filled light globes with krypton instead of argon in 1930, resulting in a much longer-lasting globe, becoming one of Hungary’s biggest exports. The gas was expensive, so in 1937, he devised a cheaper way to extract it from the air. Lucien Lévy 1892-1965 superheterodyne (superhet) circuit etc Developed a low-frequency amplifier to listen to enemy telephone communications and for other applications during WW1 (1914-1918). He invented the superheterodyne circuit, filing a patent in 1917, resulting in a patent dispute with Armstrong, resolved mostly in favour of Lévy. Robert Watson-Watt radar 1892-1973 He worked on detecting the direction of lightning strikes to warn pilots of storms from 1916. From 1935, he started working on and developing concepts to detect aircraft using radio reflections or radar. By the start of WW2, 19 radar stations had been established, ready for the Battle of Britain, and 50 were in place by the war’s end. Sir Edward Victor Appleton 1892-1965 proving the existence of the ionosphere Proved the existence of the ionosphere in 1924, a layer of the atmosphere that reflects radio waves, and won a Nobel Prize for the discovery in 1947. Homer W. Dudley 1896-1980 Vocoder (Voice Coder) – speech analysis He invented the Vocoder (Voice Coder) in 1936 at Bell Labs. It is a speech analysis and synthesis system to encode speech by analysing it and reducing it to a series of control signals. Those signals could be transmitted over a limited bandwidth connection, such as an undersea cable or radio link, then reconstructed to the original speech. Based on that work, in 1937, he and Robert Riesz invented the world’s first electronic speech synthesiser, the Voder (Voice Operation Demonstrator), receiving US patent 2,121,142. It had a human operator pressing keys to produce the sound and was challenging to operate. It was demonstrated at the New York World’s Fair in 1939. See the video titled “The Voder – Homer Dudley (Bell Labs) 1939” at https://youtu.be/5hyI_dM5cGo and the free eBook PDF at siliconchip.au/ link/abnn During WW2, he worked with Alan Turing (see his entry on page 29) on SIGSALY, a high-level cryptographic machine for voice transmissions that employed technology from Vocoder and Voder (Fig.49). Harold Stephen Black 1898-1983 negative feedback amplifiers, op amps Invented the negative feedback amplifier in 1927. It increased circuit stability, improved linearity (reducing distortion), increased the input impedance, decreased the output impedance, reduced noise, enhanced bandwidth and frequency response. Early practical applications were the reduction of overcrowding on long-­ distance telephone lines, improved Fig.47: shown at left is John Logie Baird with his Televisor, the first commercial television from 1926. The adjacent image is of Baird’s business partner, as seen on the Televisor. Source: https://rts.org.uk/article/remembering-logie-bairdninety-years Australia's electronics magazine siliconchip.com.au Fig.49: the SIGSALY highlevel voice encryption machine used in WW2. Source: https://w. wiki/7DAh Fig.50: the first point-contact transistor from 1947. Source: https://w. wiki/7DAi (CCBY-SA-3.0). fire control systems in WW2, forming the basis of operational amplifiers (op amps) and precision audio oscillators. See our article on the History of Op Amps (August 2021; siliconchip.au/ Article/14987). Russell Shoemaker Ohl solar cell 1898-1987 Ohl filed for US patent 2,402,662 in 1941 for what is regarded as the world’s first solar cell made with a silicon P/N junction. This design continued to be developed, reaching an efficiency of around 5% in the 1950s and 1960s. Russell Harrison Varian klystron (linear-beam vacuum tube) 1898-1959 He and his brother Sigurd Fergus Varian (1901-1961) invented the klystron in 1937 and published the results in 1939. It is a vacuum tube that generates microwave frequency signals. It was the first device to generate these frequencies at a reasonable power level. The Axis powers used it for jamming H2S radar during WW2 (many of the principles had already been published before the war). German radar used more conventional techniques to generate lower-frequency microwaves, while the Allies used the more powerful cavity magnetron (see the entry for Randall and Boot on page 28). Kenjiro Takayanagi all-electronic television receiver 1899-1990 He developed the world’s first all-­ electronic television receiver in 1926, with 40 lines of resolution. A Nipkow disc was used to scan the image at the source, but unlike other systems at the time, the receiver used a cathode ray tube to display the image. This was months before Philo Farnsworth demonstrated the first fully electronic TV system that did not require a Nipkow disc. In 1927, Takayanagi increased the resolution to 100 lines. Howard Aiken Harvard Mark 1 1900-1973 Aiken created the concept for the Harvard Mark 1, one of the earliest computers (see Fig.48). He went to IBM for funding the creation of the design, which was approved in 1939 and finished in 1944. Dennis Gabor holography 1900-1979 Invented holography in 1948, a process best known for the ability to reproduce 3D images but with many other Fig.48: the Harvard Mark 1, designed by Howard Aiken, is an electromechanical computer, more than 15m long. Source: Encyclopædia Britannica – www.britannica.com/technology/minicomputer#/media/1/44895/19205 siliconchip.com.au Australia's electronics magazine applications. He received the Nobel Prize for this work in 1971. Enrico Fermi & Paul Dirac Fermi-Dirac statistics Enrico Fermi (1901-1954) and Paul Adrien Maurice Dirac (1902-1984) independently created Fermi-Dirac statistics in 1926, which describe the behaviour of semiconductors. Stuart William Seeley Foster-Seeley FM discriminator 1901-1978 Seeley and Dudley E. Foster invented the Foster-Seeley FM discriminator in 1936 and published it in 1937. It would be called a demodulator today. It reduced the cost of FM radios to a comparable level to AM radios. It was widely used until the 1970s, when ICs allowed other modulator types to be used. Alfred Kastler 1902-1984 optical pumping Invented optical pumping in the early 1950s, a technique that led to the development of masers and lasers. The coherent light from lasers is crucial to semiconductor fabrication. Walter Houser Brattain magnetometers 1902-1987 He worked with a group developing magnetometers during WW2 to detect submarines and applied for US patent 2,605,072 with others, including Norman E. Klein, in 1944. In 1947, with John Bardeen and William Bradford Shockley Jr, he demonstrated the first working transistor (a point-contact design) – see Fig.50. Bardeen and Brattain were awarded a Nobel Prize for the point-contact device and Shockley for the junction transistor. Bell Labs credits 12 people as being involved with the invention of the transistor. Alan Dower Blumlein 1903-1942 weighting networks, stereophonic sound etc He measured the frequency response of human ears in 1924 to design November 2023  27 weighting networks to minimise noise and better utilise telecommunications bandwidth. In 1924, he also published work on high-frequency resistance measurements. In 1938, he submitted US patent application 2,218,902 for what was to be called an “Ultra-­ Linear” audio power amplifier. In 1931, he filed UK Patent 394,325 for what is now known as stereophonic sound, but it was only commercially exploited in the 1950s after the patent expired. “Matrix processing” was used to efficiently encode sound as a common signal between left and right and a differential signal to define the spatial distribution. After 1933, he worked on the development of television and patented several technologies, and mostly developed the 405-line Marconi-EMI TV system. During WW2, he was involved in developing the H2S radar system for the RAF to identify ground targets for night and all-weather bombing. He was killed during a flight testing the system, but it went on to be a success. Oleg Vladimirovich Losev light-emitting diode (LED) 1903-1942 Extensively studied the silicon carbide point-contact junction, discovered by H. J. Round, which emitted green light. He published the results between 1924 and 1941. He produced a device, but no one saw a use for the weak light, although Losev thought it would be useful for telecommunications. We now know this device to be a light-emitting diode (LED). John Vincent Atanasoff Atanasoff-Berry Computer (ABC) 1903-1995 He completed the Atanasoff-Berry Computer in 1942, which was under development since 1938. It is arguably the first digital computer, although it was not programmable, had no CPU and was not Turing complete (see Alan Turing’s entry opposite). Sir John Turton Randall cavity mangetron fully-electronic television system 1906-1971 Demonstrated a fully electronic TV 28 Silicon Chip Paul Eisler printer circuit board (PCB) 1907-1992 Eisler invented the modern printed circuit board (PCB) in 1936 while working in the UK. He had experience in the printing industry, which helped with the project. The ‘intellectual property’ of the invention was not well protected, as he did not read a contract he signed. There were contributions to ideas and technologies leading up to this, such as from Thomas Edison, who made electrical tracks of glue and charcoal on a substrate in 1904; Arthur Berry, who in 1913 etched metal away to make items such as heating elements; and Charles Ducas, who described plating of copper patterns onto an insulating substrate in 1925. Victor Ivanovich Shestakov switching circuit theory 1907-1987 Developed a way to implement Boolean algebra logic in electromechanical relay circuits in 1935 (switching circuit theory). This was essential for the operation of computers and other digital devices. Claude Shannon independently invented the same theory (see his entry opposite), as well as Akira Nakashima (1908-1970). Manfred von Ardenne 3NF vacuum tube 1907-1997 He obtained a patent for the 3NF vacuum tube in 1923, at age 15. It had three integrated triodes (akin to an integrated circuit) and was used in the low-cost Loewe-Ortsempfänger OE333 AM radio (Fig.52). He also produced the flying-spot scanner as a television camera in 1930 (although not a camera tube, as such) and demonstrated it at the Berlin Radio Show in 1931. John Bardeen point-contact transistor 1908-1991 Bardeen and Walter Houser Brattain demonstrated the first working point-contact transistor in 1947. Oskar Heil microwave vacuum tube 1908-1994 Published a paper in 1935, along with his wife Agnessa Arsenjeva, for a microwave vacuum tube, which subsequently led to the production of the first practical device. It predated the invention of the klystron, another type of microwave vacuum tube. He also invented the air motion transformer, used in certain high-end loudspeakers (there is a video on it at https://youtu.be/-wYxHYVO6sU). Konrad Zuse first Turing-complete computer 1910-1995 He invented the first programmable “Turing-complete” computer in Germany in 1941. William Shockley transistor 1910-1989 He led a research group at Bell Laboratories that included the co-­inventors of the transistor, John Bardeen and Walter Houser Brattain, who produced the first transistor in 1947. In 1956, he founded Shockley Semiconductor Laboratory in Mountain View, California, but unfortunately, he was regarded as a very poor manager. This led to the “traitorous eight” Fig.51 (left): the first digital voltmeter from 1952. 1905-1984 Randall and Henry Albert Howard Boot (1917-1983) invented the cavity magnetron in 1940. It was an extremely important vacuum tube device used to produce high-power microwaves for radar and other applications. The klystron, as used by the Germans then, could not produce high-power microwaves. The cavity magnetron went on to be used in microwave ovens. Philo Taylor Farnsworth system in 1927 (camera and receiver). He used a video camera tube he developed, which he called the image dissector, to capture the image. He demonstrated it to the press in 1928. Fig.52: the Loewe-Ortsemfänger OE333 AM radio used the 3NF vacuum tube made by Manfred von Ardenne. See our Vintage Radio column, in the July 2020 issue (siliconchip.au/ Article/ 14513). Australia's electronics magazine leaving and founding Fairchild Semiconductor in 1957. For more on this, see our article in the June 2022 issue on IC Fabrication (part 1; siliconchip. au/Series/382). John Robinson Pierce communications satellites 1910-2002 Published an article titled “Orbital Radio Relays” in the journal Jet Propulsion in April 1955. He was a pioneer of communications satellites and participated in the development of Telstar 1. Arthur C. Clarke acknowledged Pierce as one of two pioneers of such satellites, along with Harold Allen Rosen. Hedy Lamarr radio guidance system 1914-2000 In the early 1940s, along with George Antheil, she developed spread spectrum and frequency-hopping technology to create an unjammable (at the time) torpedo guidance system. Both techniques were used in later communications systems. Alan Turing cryptography, Turing machine etc 1912-1954 Turing is one of the founders of computer science and a significant figure in the development of cryptography. He created the concept of the Turing machine that can be used to compare the capabilities of different kinds of computers and the Turing test to determine if a machine can fool a human into thinking it’s another human. Claude Shannon 1916-2001 signal flow graphs, Minivac 601 computer Demonstrated circuits in 1936 to simplify the arrangement of relays in telephone network switches. He also invented signal flow graphs in 1942. In 1961, he designed the Minivac 601 electromechanical computer for educational purposes. There are plans to build a replica at siliconchip.au/ link/abno Sir Arthur Charles Clarke communications satellites 1917-2008 He wrote a Wireless World article in 1945 proposing what we would now call communications satellites (in particular, geostationary satellites). Harry Wesley Coover Jr super glue 1917-2011 Invented cyanoacrylate adhesives (‘super glue’) in 1942. A commercial product was not released until 1958, marketed by Kodak as Eastman 910. These adhesives bond almost instantly and have wide application in commercial electronic assembly. Andrew F. Kay digital voltmeter 1919-2014 He invented the digital voltmeter (Fig.51) in 1952. Otis Frank Boykin 1920-1982 precision wire-wound resistors, pacemakers Produced many inventions, including an improved form of precision wirewound resistor with low inductance and reactance. He also invented a precision control unit for cardiac pacemakers in 1964. Norman Joseph Woodland barcode 1921-2012 He applied for a patent for a barcode in 1949, to encode price and product description and other data (see US patent 2,612,994). It was a sound idea, but there was not yet a suitable computer to implement it. Rubin Braunstein 1922-2018 gallium and indium-based semiconductors He measured infrared emission from devices he made from the semiconductors gallium arsenide (GaAs), gallium antimonide (GaSb) and indium phosphide (InP) in 1955. This is the basis for LED lights and semiconductor lasers. David Paul Gregg optical disc 1923-2001 Invented the optical disc in 1962 (although it was discussed as early as 1958). He filed for US patent 3,381,086 in 1962, granted in 1968. Jack St. Clair Kilby first integrated circuit (IC) etc The German’s Enigma machine from WWII was cracked by Alan Turing and others. Source: https://w. wiki/7Dwg (CC-BY-SA-4.0). siliconchip.com.au 1923-2005 He is credited for the first integrated circuit (IC) in 1958, along with Robert N. Noyce. He also invented the handheld calculator and thermal printer. Seymour Cray CDC660 supercomputer 1925-1996 Designed the first silicon transistor Australia's electronics magazine Fig.53: a Cray-1 on display at the Science Museum in London. Source: https://w.wiki/7DBY (CC-BY-SA-2.0). supercomputer in 1964, the CDC660, considered the first successful supercomputer. Germanium transistors, in use until that time, were not fast enough. It was the fastest computer in the world at the time, about ten times faster than others. In 1972, Cray started his own company, Cray Research, and designed the famous Cray 1 (See Fig.53). It was released in 1976 and became one of the most successful supercomputers. Narinder Singh Kapany fibre optics 1926-2020 Kapany invented fibre optics (he coined the term). In 1953, along with Harold Horace Hopkins (1918-1994), he transmitted an image through a bundle of 10,000 optical fibres with better image quality than had previously been achieved. This led to the first practical gastroscope for medical investigations, developed by other researchers in 1956. Junichi Nishizawa 1926-2018 avalanche photodiode, solid-state maser etc Invented the avalanche photodiode in 1952, a solid-state maser in 1955 and, in 1963, proposed the idea of fibre-optic communications. He also patented graded-index optical fibres in 1964. Among his other inventions was the static induction thyristor in 1971. Robert Norton Noyce monolithic silicon IC 1927-1990 Noyce invented the monolithic silicon integrated circuit in 1959 and co-founded Fairchild Semiconductor in 1957 and Intel Corporation in 1968. November 2023  29 Credit is also given to Jack Kilby for the invention of the integrated circuit. Theodore Harold Maiman laser 1927-2007 Invented the first laser in 1960, a device to produce light with all emissions of the same wavelength and all in phase. Nick Holonyak Jr visible light laser diode 1928-2022 He invented the visible light laser diode in 1962. It lased at low temperatures and functioned as an LED at room temperature. Manfred Börner optical fibre communication system 1929-1996 Demonstrated the first working optical fibre communication system at Telefunken Research Labs in 1965. James Robert Biard infrared LED 1931-2022 Biard held numerous patents and also invented, along with Gary Pittman, an infrared LED in 1961 (receiving US patent 3,293,513). In 1962, Texas Instruments released the first commercial LED (SNX-100) for US$130 each, almost $2000 today! binary multiplier in 1964 for arithmetic operations in computers. Sir Charles Kuen Kao 1933-2018 reducing signal attenuation in optical fibres He and George Alfred Hockham (1938-2013) at British STC proposed that making optical fibres out of more pure materials could dramatically reduce signal attenuation in 1965. Today, losses in optical fibres are extremely low, making repeaters only necessary every 70-150km. George Harry Heilmeier liquid crystal displays (LCDs) 1936-2014 Discovered effects in liquid crystals in 1964, which led to the first liquid crystal displays (LCDs) using what he called dynamic scattering mode (DSM). Gary Keith Starkweather laser printer 1938-2019 He invented the laser printer in 1969. The first commercial laser printer on the market was the IBM 3800, released in 1976 to replace line printers, with the Xerox 9700 following in 1977 for high-quality printing. Another reason the 9700 is significant is that when Xerox refused to supply code for that printer (as they had done for a previous model) in 1980, Richard Stallman (see below) and others at the MIT AI Lab started the free software movement. Richard Stanley Williams memristor 1951~ Developed a practical version of the memristor (memory resistor ) at HP in 2008. The memristor was first postulated in 1971 by Leon Ong Chua (1936~). Richard Matthew Stallman GNU project, GCC, Emacs 1953~ He started the free software movement in 1980 and, in 1983, founded the GNU Project. He also founded the Free Software Foundation (FSF) in 1985. The tools developed by the GNU Project were instrumental for Linus Torvalds and others to make Linux a practical operating system. Linus Torvalds 1969~ Linux operating system The driving force behind the opensource Linux operating system. However, thousands of others have significantly contributed to its development, including Andrew Morton, Alan Cox, Greg Koah-Hartman and Ingo Molnar. Linux is licensed under the GNU GPL. Linux currently powers the majority SC of the world’s top web servers. Songbird Chris Wallace hardware binary multipler 1933-2004 Wallace invented the hardware An easy-to-build project SC6633 ($30 plus $12 postage*): Songbird Kit that is perfect as a gift. * flat rate postage Australia-wide Choose from one of four colours for the PCB (purple, green, yellow or red). The kit includes nearly all parts, plus the piezo buzzer, 3D-printed piezo mount and switched battery box (base/stand not included). See the May 2023 issue for details: siliconchip.au/Article/15785 30 Silicon Chip Australia's electronics magazine siliconchip.com.au