7 Edwin H. Armstrong 7motor cars, he developed no other significant interests.
Wireless was then in the stage of crude spark-gap trans-
mitters and iron-filing receivers, producing faint
Morse-code signals, barely audible through tight ear-
phones. Armstrong joined in the hunt for improved
instruments. On graduating from high school, he com-
muted to Columbia University’s School of Engineering.
In his junior year at Columbia, Armstrong made his
first, most seminal invention. Among the devices inves-
tigated for better wireless reception was the then little
understood, largely unused Audion, or three-element
vacuum tube, invented in 1906 by Lee De Forest, a pio-
neer in the development of wireless telegraphy and
television. Armstrong made exhaustive measurements to
find out how the tube worked and devised a circuit, called
the regenerative, or feedback, circuit, that suddenly, in the
autumn of 1912, brought in signals with a thousandfold
amplification, loud enough to be heard across a room. At
its highest amplification, he also discovered, the tube’s
circuit shifted from being a receiver to being an oscillator,
or primary generator, of wireless waves. As a radio wave
generator, this circuit is still at the heart of all radio-television
broadcasting.
Armstrong’s priority was later challenged by De Forest
in a monumental series of corporate patent suits, extend-
ing more than 14 years, argued twice before the U.S.
Supreme Court, and finally ending—in a judicial misun-
derstanding of the nature of the invention—in favour of
De Forest. But the scientific community never accepted
this verdict. The Institute of Radio Engineers refused to
revoke an earlier gold-medal award to Armstrong for
the discovery of the feedback circuit. Later he received the
Franklin Medal, highest of the United States’ scientific
honours, reaffirming his invention of the regenerative
circuit.