One of the foundational elements of all electronic devices today is the transistor, a semiconductor device including three terminals which i...
One of the foundational elements of all electronic devices today is the transistor, a semiconductor device including three terminals which is capable of amplifying an electric current or voltage which is applied to one of the terminals and output through another terminal.
It’s no understatement to say that modern electronic devices couldn’t function without a component that can process electrical signals in the manner accomplished by a transistor. Yesterday’s transistors have largely been replaced by today’s integrated circuits, which are capable of much more complex processing of electrical signals, but the discovery of the transistor was a huge turning point in the electronics industry of the mid-20th century.
The invention of the transistor has been hailed as a milestone achievement by the Institute of Electrical and Electronics Engineers (IEEE). In 2011, state-of-the-art processing units contained as many as 2.9 billion transistors on a single chip.
In 1974, a trio of engineering luminaries were inducted into the National Inventors Hall of Fame for their seminal contributions to the creation of the transistor. William B. Shockley, John Bardeen and Walter H. Brattain are the trio credited with developing the first commercially successful transistor product in the 1940s at the widely heralded American research and development facility Bell Labs. This April 4th marks the 67th anniversary of the issue date for one of two patents for which this trio of innovators has been inducted into the Hall of Fame, giving us a good occasion to look back at the development of this incredibly important 20th century invention.
De Forest’s Audion Enables Amplification in Vacuum Tubes, But Issues Remained
For decades prior to the advent of the transistor, the amplification of electrical signals was achieved through the use of vacuum tubes. Invented in 1904 by British electrical engineer John Ambrose Fleming, vacuum tubes consisted of two electrodes within a glass-enclosed vacuum which enabled an electric current to flow between the two electrodes. Although Fleming invented the first widely used vacuum tube, the first “audion” vacuum tube device capable of amplification was invented in 1907 by American inventor Lee De Forest, a pioneer in early radio and motion picture technologies. Such amplification enabled electrical currents to be directed further along a cable without weakening.
The ability to control and amplify an electric current using vacuum tubes made these devices an incredibly important component of electronic systems built in the early 20th century. For example, De Forest’s audions became a central component to the first cross-country telephone line constructed by AT&T which could transmit a telephone call signal up to 3,400 miles by July 1914. Audions installed in Pittsburgh, Omaha and Salt Lake City supported this first cross-country phone line by boosting the call’s electrical signal at strategic points along the way.
The vacuum tube did have serious drawbacks which the transistor would improve upon, however. Vacuum tubes were constructed of glass and any cracks would disrupt the vacuum and cause the tube to stop working properly. Vacuum tubes would also generate a great deal of heat which increases the risk of glass cracking and contributes to the degeneration of internal components.
