Lee de Forest was one of the most important of the inventors of radio and electronic technology, a formally educated scientist whose inventions touch every life.
He is most known for his pioneering work with the vacuum tube, first as a detector of radio waves, then as an amplifier for long distance telephone calls, and finally as the major technology of the radio transmitter, still in use today. De Forest with his famous Audion, 1950
Lee de Forest was born in Council Bluffs, Iowa (USA) on August 26, 1873. De Forest was the son of a Congregational minister. His father moved the family to Alabama and there assumed the presidency of the nearly bankrupt Talladega College, a small black school. Ostracized by citizens of the white community who resented his father’s efforts to educate blacks, Lee made his friends from among the black children of the town and, together with his brother and sister, spent a happy although sternly disciplined childhood in this rural community.
As a child he was fascinated with machinery and was often excited when hearing of the many technological advances during the late 19th century. By the age of 13 he was an enthusiastic inventor of mechanical gadgets such as a miniature blast furnace and locomotive, and a working silverplating apparatus. But while de Forest grew up in the deep South, his education was formal and upper class.
Lee de Forest’s father hoped that his son would follow in his footsteps. In order to be trained for this calling, de Forest left Alabama to attend Mt Hermon boys school in Massachusetts. His life at school was hard, with chores as well as academics, plus work to supplement his scholarship.
Besides, he was not well-liked there. Biographers report he was extremely concerned with getting recognition from his peers, an issue which lasted throughout his life. Alas, he only won acknowledgement as “homeliest boy in school.” Despite this, he was confident. During school, de Forest had tried to get money and fame by inventing things he might sell or enter in contests, but none were great successes.
His father had planned for him a career in the clergy, but Lee insisted on science and, in 1893, enrolled at the Sheffield Scientific School of Yale University, one of the few institutions in the United States then offering a first-class scientific education. Frugal and hardworking, he supplemented his scholarship and the slim allowance provided by his parents by working at menial jobs during his college years, and, despite a not too distinguished undergraduate career, he went on to earn the Ph.D. in physics in 1899.
By this time he had become interested in electricity, particularly the study of electromagnetic wave propagation, then being pioneered chiefly by the German Heinrich Rudolf Hertz and the Italian Guglielmo Marconi. De Forest’s doctoral dissertation on the “Reflection of Hertzian Waves from the Ends of Parallel Wires” was possibly the first doctoral thesis in the United States on the subject that was later to become known as radio.
Lee de Forest receiving Ph.D., Yale University, 1899
His first job was with the Western Electric Company in Chicago, where, beginning in the dynamo department, he worked his way up to the telephone section and then to the experimental laboratory. While working after-hours on his own, he developed an electrolytic detector of Hertzian waves. The device was modestly successful, as was an alternating-current transmitter that he designed.
A poor businessman and a poorer judge of men, de Forest was defrauded twice by his own business partners. In 1902 de Forest joined a Wall Street promoter named Abraham White and formed the de Forest Wireless Telegraph Company. Among their early customers were the War Department and the Navy. In order to dramatize the potential of this new medium of communication, he began, as early as 1902, to give public demonstrations of wireless telegraphy for businessmen, the press, and the military.
Under the guidance of White, a public offering of stock was made, public demonstrations were held, and radio equipment was sold. But characteristic of his entire career, the hyperbole surrounding the company was greater than its actual value, and while de Forest continued to invent, he was apparently unaware that White was engaging in less than ethical business practices. By 1906 his first company was insolvent, and he had been squeezed out of its operation.
The picture shows discredited de Forest associate Abe White standing behind de Forest, seated, who is operating a telegraph key.
During his lifetime, Lee de Forest received over 180 patents. But de Forest is most known for his contributions and improvements to the basic invention of all radio and television, the vacuum tube. In 1907 he patented a much more promising detector which he called the “Audion”; it was capable of more sensitive reception of wireless signals than were the electrolytic and Carborundum types then in use.
It was a thermionic grid-triode vacuum tube – a three-element electronic “valve” similar to a two-element device patented by Sir John Ambrose Fleming in 1905. By 1906 de Forest had modified Fleming’s valve by adding a grid to control and amplify signals, and called his device the Audion. At the right is the original Audion patent, dated January 15, 1907. The Audion was used as a detector of radio signals, an amplifier of audio and an oscillator for transmitting.
Many inventors tried to improve the Fleming diode, most without success. The only one who succeeded was New York inventor Lee de Forest. In 1907 he patented a bulb with the same contents as the Fleming diode, except for an added electrode. This “grid” was a bent wire between the plate and filament. De Forest discovered that if he applied the signal from the wireless-telegraph antenna to the grid instead of the filament, he could obtain a much more sensitive detector of the signal.
In fact, the grid was changing (“modulating”) the current flowing from the filament to the plate. De Forest was extremely creative and energetic, but often was unable to see the potential of his inventions or grasp their theoretical implications. For example, he created the Audion, a vacuum tube containing some gas. De Forest thought the gas was a necessary part of the system. In 1912, others showed that a triode in a complete vacuum would work far better.
The Audion, was the first successful electronic amplifier. It was the genesis of today’s huge electronics industry. Between 1907 and the 1960s, a staggering array of different tube families was developed, most derived from de Forest’s invention. With a very few exceptions, most of the tube types in use today were developed in the 1950s or 1960s. One obvious exception is the 300B triode, which was first introduced by Western Electric in 1935.
Lee de Forest was a fan of the opera, and he claimed in his writings that he before anyone else believed that the radiotelephone would be an excellent way to send musical entertainment into homes. In 1907 he formed the de Forest Radio Telephone Company. In a de Forest company advertisement issued in 1907, he wrote: “It will soon be possible to distribute grand opera music from transmitters placed on the stage of the Metropolitan Opera House by a Radio Telephone station on the roof to almost any dwelling in Greater New York and vicinity… The same applies to large cities.
Church music, lectures, etc., can be spread abroad by the Radio Telephone.” In 1910 he broadcast a live performance by Enrico Caruso at the Metropolitan Opera in order to further popularize the new medium. The second company, the de Forest Radio Telephone Company, began to collapse in 1909, again because of some of his partners. In the succeeding legal confusion, de Forest was indicted in 1912 but later acquitted of federal charges of using the mails to defraud by seeking to promote a “worthless device” – the Audion tube.
Newspaper stories show that in 1910 he used his radiotelephone to send the voices of opera singers to members of the press stationed at receiving sets. And when testing the radiotelephone for the Navy, he played patriotic phonograph music as the ships entered the harbor.
Moving to California in 1910, he worked for Federal Telegraph Company at Palo Alto. While there, de Forest finally made his Audion tube perform as an amplifier and sold it to the telephone company as an amplifier of transcontinental wired phone calls. For this innovation he received $50,000.
By the beginning of 1916, he had finally perfected his Audion for its most important task, that of an oscillator for the radiotelephone transmitter. By late 1916 de Forest had begun a series of experimental broadcasts from the Columbia Phonograph Laboratories on 38th Street, using for one of the very first times his Audion as a transmitter of radio: According to de Forest, “The radio telephone equipment consists of two large Oscillion tubes, used as generators of the high frequency current.”
In 1912 de Forest conceived the idea of “cascading” a series of Audion tubes so as to amplify high-frequency radio signals far beyond what could be accomplished by merely increasing the voltage on a single tube. He fed the output from the plate of one tube, through a transformer to the grid of a second, and the output of the second tube’s plate to the grid of a third, and so forth, thereby allowing for an enormous amplification of a signal that was originally very weak. This was an essential development for both radio and telephonic long-distance communication.
De Forest also discovered in 1912 that by feeding part of the output of his triode vacuum tube back into its grid, he could cause a self-regenerating oscillation in the circuit. The signal from this circuit, when fed to an antenna system, was far more powerful and effective than that of the crude transmitters then generally employed and, when properly modulated, was capable of transmitting speech and music. When appropriately modified, this single invention was capable of either transmitting, receiving, or amplifying radio signals.
Soon after that, de Forest had a decades long court battle with Edwin Armstrong over who first discovered the regenerative characteristics of the Audion. Regeneration is feedback; a small signal from the output of a vacuum tube is fed back into the input, thus making weak signals very strong. Both de Forest and Armstrong claimed its discovery, and while the litigation lasted from 1914 to 1934, and the courts would finally side with de Forest, the technical community did not.
It was a hollow victory which destroyed both claimants. Distraught over the court loss to de Forest and other problems, Edwin Armstrong committed suicide in 1954. So in the long legal battle over who had the rights to the regenerative properties of the vacuum tube, de Forest may have won the battle, but in the court of public opinion he probably lost the war. As a result he was not taken seriously as an inventor or trusted as a colleague. In the newspaper photo at the left, de Forest is testifying in one of the many legal arenas that marked and finally defined his career.
Happiness to de Forest was his New York home which he called Riverlure. On the banks of the Hudson, he was forced to sell it to pay his court debts.
De Forest’s inventions provided the possibility of a wireless telegraphy (radio). Some of the early radio receivers based on de Forest’s Audion tube and other related tubes are shown below.
Scheme of the first and second versions of the de Forest Model D-12 Radiophone (radio receiver)
The plate on the front of the receiver in part reads: DE FOREST AUDION TIME RECEIVER. SET FOR U.S. TIME SIGNALS FROM ARLINGTON, VA. The Navy’s high-power station, NAA in Arlington, Virginia, had begun operation a couple years earlier, and was best known for broadcasting daily time signals.
Because the station was not capable of transmitting full audio, the correct time was signaled by a series of preliminary dots, followed by a dash at the top of the hour. Based on the description, this receiver used a simple regenerative circuit – called an “ultra audion” in DeForest parlance – permanently tuned to NAA’s operating wavelength of 2,500 meters (120 kH) (from Radio History).
De Forest radiophone receiver manufatured in 1930 in Passaic, NJ. The radio tunes from 1.5 to 20 Mhz. with bandswitching via the plug in coil set pictured.
Throughout de Forest’s lifetime the originality of his more important inventions was hotly contested, by both scientists and patent attorneys. In time, realizing that he could not succeed in business or manufacturing, he reluctantly sold his patents to major communications firms for commercial development. Some of the most important of these sales were made at very low prices to the American Telephone & Telegraph Company, which used the Audion as an essential amplification component for long-distance repeater circuits.
Many have believed that the early de Forest radiotelephone transmitters were based on his famous audion tube. This is not true. Until 1916 de Forest, like Charles Herrold and practically every early broadcaster of voice and music used some version of the Poulsen DC arc for voice transmission. For the de Forest “broadcasts” in 1916, the tube replaced the arc.
Lee de Forest operated his station 6XC from the California Theater at Fourth and Market Streets from April, 1920 to November, 1921. He had previously operated this equipment at his broadcasting station in New York. Here he is shown demonstrating his 500 watt transmitter to Miss Mary White, one of the many entertainers who performed on the station. In late 1921, the transmitter was moved to Oakland and 6XC became KZY, the Rock Ridge Station.
Later, de Forest was asked to talk about his early Oscillion transmitters. He was the first to broadcast election returns to an audience. While many believe that KDKA in 1920 was the first, it was from High Bridge New York in 1916 that de Forest broadcast for a rather large audience the Hughes-Wilson Election returns from the newsroom of the New York American.
In the 1950s, in the photo to the left, de Forest posed with his 1920 Oscillion transmitter of the kind he constructed and installed for another early broadcast pioneer, WWJ, the Detroit News station. Also in 1920, de Forest set up a radio station in San Francisco, again using another version of this transmitter.
In his final years de Forest was disillusioned at what radio programming had become. Believing himself to be the “Father of Radio” he asked reporters in the early 1950s, “Why should anyone want to buy a radio… nine tenths of what one can hear is the continual drivel of second-rate jazz, sickening crooning by degenerate sax players, interrupted by blatant sales talks?”
De Forest created the “Audion Piano”, the first vacuum tube instrument in 1915. The Audion Piano was a simple keyboard instrument but was the first to use a beat-frequency (heterodyning) oscillator system and body capacitance to control pitch and timbre ( The heterodyning effect was later exploited by the Leon Termen with his Theremin series of instruments and Maurice Martenot’s Ondes-Martenot amongst others.)
The Audio Piano used a single triode valve per octave which were controlled by a set of keys allowing one note to be played per octave. The output of the instrument was sent to a set of speakers that could be placed around a room giving the sound a dimensional effect. De Forest planned a later version of the instrument that would have separate valves per key allowing full polyphony – it is not known if this instrument was ever constructed.
De Forest described the Audio Piano as capable of producing: “Sounds resembling a violin, Cello, Woodwind, muted brass and other sounds resembling nothing ever heard from an orchestra or by the human ear up to that time – of the sort now often heard in nerve racking maniacal cacophonies of a lunatic swingband. Such tones led me to dub my new instrument the ‘Squawk-a-phone’.” (Lee de Forest Autobiography “The Father of Radio” 1915, pp. 331-332)
In 1926, 27 years after receiving his Ph.D., Lee de Forest was invited back to Yale and presented with an honorary Doctorate.
Lee de Forest had four wives. The first of these, in 1906, was Lucille Sheardown, a marriage that was not consummated and ended in divorce that same year. The second, in 1907, was Nora Blatch (the grand-daughter of the famous women’s rights activist Elizabeth Cady Stanton), who bore him a child, but Nora was a liberated woman with an engineering background.
After a few years she realized that she did not want to live in the shadow of de Forest, and by 1911 they were divorced. By 1912, de Forest had remarried, this time to singer Mary Mayo. Several children resulted. They remained together and happy for nearly 15 years and together had two children, one of whom died at birth.
Final marital bliss happened in Hollywood. Lee was most happy with his 4th wife, actress Marie Mosquini. They lived happily ever after in Hollywood (pictures below).
In his later 30 years Lee de Forest lived in Hollywood and worked on a variety of non-radio technical devices, like guidance systems for bombs. But most notable was his Phonofilm process, a way to make the movies talk by adding a synchronized optical soundtrack to the film. For that 1920 invention, the first sound-on-film process, he received in 1959 an honorary Oscar from the Academy of Motion Picture Arts and Sciences. The inscription reads: “Academy Honorary Award to Lee de Forest for his Pioneer Invention which brought Sound to the Motion Picture.”
The de Forest technology called Phonofilm, was invented in 1920 and was the very first sound-on-film process. It was demonstrated in theatres between 1923 and 1927. And while almost decade earlier than the Warner Vitaphone system, it was not the system used in the 1928 film, the “Jazz Singer.” The Vitaphone system attempted to synchronize its sound with the picture using a Rube Goldberg device consisting of a record player turntable connected to the film projector.
The sound was recorded on an ordinary vinyl disc like the one used today for music. The de Forest process, the one we use today for analogue film audio, uses a device called a light valve to expose a series of light and dark areas right on the film itself, and those areas are read by a photocell and converted to audio. Although basically correct in principle, its operating quality was poor, and he found himself unable to interest film producers in its possibilities. Ironically, within a few years’ time the motion-picture industry converted to talking pictures by using a sound-on-film process similar to that of de Forest.
Vitaphone was a sound film process used on several features and shorts produced by Warner Brothers in the late 1920s and early 1930s. Many early talkies, such as The Jazz Singer, used the Vitaphone process. Vitaphone was the last of the so-called sound-on-disc processes, and its technical imperfections led to its retirement early in the sound era. A Vitaphone-equipped theater used special projectors, an amplifier, and speakers. The projectors operated as normal silent projectors would, but also provided a mechanical interlock with an attached phonograph turntable.
When the projector was threaded, the projectionist would align a start mark on the film with the picture gate, and would at the same time place a phonograph record on the turntable, being careful to align the phonograph needle with a arrow scribed on the record’s label. When the projector rolled, the phonograph turned at a fixed rate, and (theoretically) played sound in sync with the film passing the picture gate simultaneously. (see more: 1, 2 )
Lee De Forest, known as the father of radio as a result of his invention of the Audion tube in 1906, poses in a 1922 photo with a strip of his Phonofilm sound-on-film.
Lee de Forest in 1948
During the 1930s de Forest developed Audion-diathermy machines for medical applications and, during World War II, conducted military research for Bell Telephone Laboratories. Although bitter over the financial exploitation of his inventions by others, he was widely honoured as the “father of radio” and the “grandfather of television”. He was supported strongly but unsuccessfully for the Nobel Prize for Physics.
Lee De Forest, ca. 1940
Lee de Forest was a prolific writer. At the beginning of his inventing career, he was a contributor to scientific journals and popular electronics periodicals. He wrote a self published autobiography, “Father of Radio,” in 1950. He kept a daily journal, he wrote thousands of business and personal letters, several film scripts, and many poems. Much of this correspondence is housed at the Perham Foundation Electronics History Museum. Lee de Forest wrote many technical and scientific articles.
Lee de Forest was accused on more than one occasion of dishonest business practices. One of the earliest happened in 1903 during a casual visit by de Forest to fellow inventor Reginald Fessenden’s workshop. Apparently de Forest, impressed by Fessenden’s invention of the Liquid Barretter detector, stole the design and claimed it as his own invention. After three court appearances, Fessenden finally received an injunction against de Forest for patent infringement.
Although he worked for many organizations during his lifetime, de Forest was fundamentally an individualist and produced most of his inventions as a free-lance worker. A complex and private man, de Forest was assailed by self-doubts, indecision, and egocentricity.
Although de Forest was responsible for some of the more significant technical radio accomplishments of the Twentieth Century, his career was one of continuing controversy; he was accused of stealing inventions from Fessenden and Armstrong, he was accused but not convicted of business fraud, and his continual exaggeration of the facts surrounding his life and career caused him to become estranged from the engineering establishment. Even though he wrote an autobiography proclaiming himself, “the Father of Radio,” he never received the respect he actively sought his entire life.
In 1956, de Forest was presented with several awards, one of which was the plaque, left, which was to mark the building site in New York where in 1906 the “grid Audion or 3 element vacuum tube” was invented.
Lee de Forest’s accomplishments in the area of radio technology were both huge and unrequited. His vacuum tube innovations between 1906 an 1916, although clouded by court battles, were nevertheless significant and long lasting.
In his later years De Forest lived in Hollywood and worked on a variety of non-radio technical devices. He continued to promote his legacy as the “Father of Radio,” but his most important non-technical contributions to radio, his publicized pre-1920 broadcasts were far in the past. He became increasingly paranoid, believing that his failure to achieve recognition was because of his “enemies.” He died on 30 June 1961 at age 87, in Hollywood, California, and was buried in San Fernando Mission Cemetery.