Lee de Forest

Lee de Forest: The Third Wire That Built the Century

The object was a small glass bulb with three electrodes inside it, and Britannica's verdict on what it did is not cautious: the Audion "made possible live radio broadcasting and became the key component of all radio, telephone, radar, television, and computer systems before the invention of the transistor in 1947." The man who patented it spent the following half-century in courtrooms, bankruptcies and fraud investigations, went through three failed marriages, and died in 1961 having never been granted by his peers the title he wanted above all others.

The Boy Who Forged a Letter to Edison

Lee de Forest was born on 26 August 1873 in Council Bluffs, Iowa. He was fascinated by machinery as a boy, and his father, who intended him for the ministry, was against it. The young de Forest's response was characteristic of everything that followed: he forged his father's signature on a letter to Thomas Edison, asking for advice about a career in engineering. Edison never replied. His father eventually gave way.

Yale

Before entering Yale in 1893 he worked at the Chicago World's Fair to raise the money, including a stint as a strikebreaker on the grounds crew. He took a B.S. and then a doctorate in physics, completing a dissertation in 1899 titled "Reflection of Hertzian Waves from the Ends of Parallel Wires" — a thesis on radio waves written before radio existed as an industry. He was, unusually for an American inventor of the period, a properly trained physicist. He went first to Western Electric in Chicago, working his way into the experimental laboratory, and in 1902 founded the De Forest Wireless Telegraph Company in New York. It did not last.

The Audion

The breakthrough came from a modification to an existing device. John Ambrose Fleming had built a two-electrode valve that could rectify a signal — detect it, but do nothing more. De Forest inserted a third electrode, a grid, between the cathode and the anode. The result was a component that could act as both detector and amplifier: a small voltage on the grid controlled a much larger current flowing through the tube.

Amplification is the whole of modern electronics. Without it a radio signal fades to nothing, a telephone call cannot cross a continent, a television picture cannot be built and a computing circuit cannot switch. He patented the Audion — U.S. Patent No. 879,532 — and the National Inventors Hall of Fame, which inducted him in 1977, calls it the most important of his more than 300 patents. He also found that feeding the tube's output back into the grid produced regenerative oscillation, permitting far more powerful transmission.

Armstrong

That discovery led to the defining fight of his life. Edwin Armstrong used the Audion to develop a regenerative circuit that was vastly more effective and commercially successful than anything de Forest built. The two men litigated for years, and de Forest won the patent case. The verdict did not settle the matter: his peers took the view that the real scientific achievement belonged to Armstrong. It is a distinction that follows him — legally vindicated, professionally doubted.

The Broadcaster

In 1916 de Forest set up a radio station in the Bronx, making him one of the earliest broadcasters in the world, years before commercial radio existed as a business. He could not capitalise on it. He clung to spark transmitters, which the technology was already leaving behind, and never worked out how to make money from broadcasting — a failure of commercial imagination in the man who had made broadcasting technically possible.

Sound on Film

During the 1920s he developed an optical system for recording sound directly onto motion picture film. It was, again, early and, again, badly executed: the operating quality was poor and Hollywood would not take it. The industry subsequently adopted a process very similar to his own. His business career was a repeating pattern of bankruptcies and suspicions of fraud, and the reputational damage was permanent.

Recognition arrived anyway. He received the Medal of Honor of the Institute of Radio Engineers in 1922 and the Edison Medal in 1946, the latter "for pioneering achievements in radio and for the invention of the grid-controlled vacuum tube." He died on 30 June 1961.

Why Lee Is Called a Genius

The case for de Forest reduces to one idea, and it is enormous. Adding a third electrode to a two-electrode valve sounds like an incremental adjustment; it was the invention of electronic amplification, and the entire twentieth century of electronics runs through it until the transistor arrived in 1947. Very few single components have carried radio, long-distance telephony, radar, television and early computing on their back. He was also genuinely trained rather than merely lucky, holding a Yale doctorate on the propagation of radio waves, and he was persistently, sometimes recklessly, early — broadcasting in 1916 and recording sound on film in the 1920s, in both cases before the world was ready to buy.

The counter-case is unusually strong, and honesty requires giving it room. De Forest built on Fleming's valve rather than starting from nothing, and his grasp of why the Audion worked was incomplete; the physics was clarified by others. On the regenerative circuit, the courts sided with him and his profession did not, which is the harshest possible verdict on an inventor. Of his 300-plus patents, essentially one matters. As a businessman he was close to a disaster — repeated collapses, fraud suspicions, an inability to convert any of his priority into a working enterprise. He craved the title "Father of Radio" and never earned it from the engineers whose opinion counted. The fairest summary may be that the Audion was a work of genius and its inventor was something more complicated: a gifted, erratic, self-promoting man who reached into the dark once and pulled out the future.

Legacy

Every amplifier, every transmitter and every switching circuit built between 1907 and the rise of the transistor descends from the grid de Forest put inside a glass bulb, and the transistor itself was designed to do the same job with less heat and less glass. Broadcasting, the recording industry, sound cinema and the first generation of computers all rest on that one modification. He lost the arguments, the companies and the credit he wanted, and still ended up embedded in the wiring of the modern world.

Achievements

• National Inventors Hall of Fame — 1977
• Legion of Honour
• Notable work: triode
• Affiliated with Illinois Institute of Technology
• Educated at Yale University, Yale School of Engineering and Applied Science and Northfield Mount Hermon School
• Worked as physicist, inventor and film director