Transistor is on of the most important inventions of the 20th century. It is one of the most common elements of electronic circuits today. This article is dedicated to the story behind the invention of transistor.
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| An old Swedish telephone from year 1896 |
The need for communication is indeed a primitive one. Ancient tribes had foot runners for conducting their messages, some trained pigeons to carry scripts for them. Then the kingdoms rose and cavaliers were born and then came the post and telegram. The first change in our way of communication was brought about with the invention of radio. But the story of transistors begins only after another great invention that came about in the year 1876, telephone.
Alexander Graham Bell invented the telephone
and brought about a revolution in communication technology and it was the Bell
Laboratories that would ultimately lead to the birth of transistor. But that is
for later. By 1907 AT&T, a telephone company founded by Graham Bell was
facing a tough competition for leadership in the industry. The operation of
telephone had not changed much by then and the technology for long distance
call simply did not exist.
The greatest
problem that the telephone faced was the need for amplification. As the
telephone signal was conducted through copper wires the signal weakened and
could not be carried to significant distances. Hence, no telephone operator
could conduct a call from the east coast to the west coast of the USA. This led
to a race among the telephone companies for finding technology to achieve the
feat. AT&T invited anyone with an idea to contact them. One person who did
contact them was an independent inventor named Lee De Forest.
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| An award containing a replica of the first transistor |
In 1906 De
Forest had invented something called the Audion. It was the first of three
element vacuum tube which was primarily being used as a radio wave detector.
Though this device provided amplification it was not enough for the needs of AT&T.
The solution was brought about by creating a better vacuum in the Audion. This
was the first useful amplifier in the world. Using this device, in 1914,
AT&T was able to complete the first transcontinental line.
Though they led
to great achievements, vacuum tubes had great problems too. They were power
hungry, they heated up very quickly, and they wore out and had to be frequently
replaced. With all these problems at hand AT&T set up the Bell Laboratories
to find a solution. The problem, it was concluded, was the vacuum. Hence they
decided to create a solid state device to replace the Audion.
During the World
War II the Americans were already using semiconductor diodes in there radio
devices and the science of Quantum Mechanics had also taken a great leap. They
saw their solution in this scheme. With
conditions in favour of electronics the scientists at AT&T’s Bell
Laboratories set out with a daunting task, to make an amplifier using
semiconductors.
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| John Bardeen, William Shockley and Walter Brattain |
The head of the
department was William Shockley. Out of the other great minds in the project
two important people were John Bardin a theoretical physicist and Walter Braton
an experimental physicist. On December 16 of the year 1947 after more than
ten years of relentless effort for the first time in history they were able to
amplify an electrical signal using a solid state device. On December 23rd they
demonstrated their device to fellow scientists and that is how the transistor
was born.
(Inspired by a BBC documentary I had originally written this piece for our college magazine but the editors of the magazine weren't interested. Didn't know what to do with it so posted it on the blog. I hope that you will like it.)
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