History and Development of Radio

Heavy Science Content
Baghdad battery – 250 BCE
Electricity was a heavy duty toy for decades,
including Ben Franklin and his kite, people
rubbing cat skins on glass or amber rods,
spinning sulfur balls, and sparking everything
and everyone in sight
Luigi Galvani - 1786
Believed everything
contained electricity
Looked for “animal
Touched different metals
to frogs’ legs which
Alessandro Volta - 1796
Alessandro Volta - 1796
Volta took Galvani’s
experiment and showed that it
was the current produced by
the different metals that
caused the twitch
Built a pile of alternating
sandwiches of zinc and
copper in an acid and created
Hans Christian Oersted - 1820
Oersted’s experiment - 1820
In a lecture in Copenhagen he performed an
experiment to demonstrate there was no
connection between electricity and magnetism
by showing that an electric current passing
through a wire wouldn’t affect a nearby compass
Imagine his surprise
when the needle swung
the moment he turned
on the current
He demonstrated that
electricity created a
magnetic field
William Sturgeon - 1825
Created the first
electromagnet by
wrapping wire around
a soft iron bar and
sending a current
through the wire
Electricity can create
Michael Faraday - 1826
Reversed Sturgeon’s
Showed that magnetism
could create an electric
Samuel F. B. Morse - 1838
Used a an on-off switch
– the telegraph key – to
turn an electric current
on and off, sending
pulses of current through
a wire to an
electromagnet that would
click in time to the pulses
Johannes Mueller - 1840
Examined physical sensations
Can you feel colors
 Can you hear shapes
 Can you smell sounds
Discovered that each sense detects different
We think this is obvious, but no one had proven
it before. Remember “common sense”?
Herman Hemholtz - 1857
Meuller’s pupil
Investigated hearing
Noticed sound produced vibrations
Did the vibrations operate at different
They did
 Thus, sound traveled at different frequencies
Used an electromagnet to attract the arms of a
tuning fork, causing it to vibrate and produce
Leon Scott de Martinville phonautograph - 1857
Attached a bristle to a
membrane at the end of a
cone, set the bristle to touch
a piece of smoked glass
Spoke into the cone
membrane vibrated to the
sound and the bristle etched a
wavy line onto the smoked
The Telephone - 1876
Scott’s membrane, Faraday’s electromagnet,
Oersted’s and Sturgeon’s electromagnet, Morse’s
wire and electrical current, Heimholtz’s
vibration, Scott’s membrane
Bell and Gray
Samuel Morse
Heinrich Hertz - 1886
Hemholtz’s pupil
Investigated whether electricity traveled in
frequencies the way sound did
Spark gap generator
Hertz’ spark gap experiment
Demonstrated that electricity
traveled through air at specific
frequencies, just like it did
through wires
Guglielmo Marconi - 1894
Marconi radio
Morse key
Marconi and his radio
Nikola Tesla
Tesla coil - 1891
Developed the first
amplifier coil, the Tesla
Raised the voltage of an
electrical current high
enough to allow the air
to conduct the current
Key to wireless
transmission of radio
Reginald Fessenden
Felt that the variation in electrical amplitude
created by a voice, just like on a telephone,
could be carried by electrical wave of a radio
Did the first voice broadcast in 1900
Short range
 Poor quality
Needed far more power
Ernst Alexanderson
Developed the Alexanderson Alternator, a
machine capable of generating the power, up to
100,000 hertz, that Fessenden needed to
piggyback voice onto radio waves
In Dec. 1906, Fessenden did the first good voice
and music broadcast, going hundreds of miles
Poetry and a Bible reading
 A woman singing opera
 A violin playing a Christmas carol
Lee de Forest
The audion tube is actually a Fleming valve
(British term for tube) invented in England
de Forest simply added the bent wire
De Forest’s audion tube - 1904
Audion tube amplified the radio signal the way
the Alexanderson generator increased the
electrical power
de Forest didn’t know how the audion worked
Another man did
Edwin Howard Armstrong
Investigated the audion tube, figured out how it
worked, and improved it
Developed “regeneration”
The signal was fed back into the tube over and over
again, up to 20,000 times a second
 Vastly increased the power of the tube to output the
signal – it was an amplifier
 Raise the level enough and the tube becomes a
 Armstrong invented the ability to broadcast sound
It combined high frequency waves with low
frequency waves, then fed them back into the
system to amplify the signal and increase its
Resulted in the creation of the home, and the
portable, radio
Armstrong’s superheterodyne
 Armstrong’s
invention was the
Crystal Radio
David Sarnoff
Enamored of radio
Saw the possibilities
Wrote the “Radio Music Box Memo” that
outlined the commercial possibilities of radio
RCA (Radio Corporation of America)
After World War I
Four companies merged their patents to create
American Marconi
 General Electric
 American Telephone & Telegraph
 Westinghouse
Sarnoff named as commercial manager
Used Armstrong’s inventions, building
superheterodyne radios to build RCA, the Radio
Corporation of America, into one of the biggest
companies in the world
Radio stations soon
opened all over the U.S.
Including KWSC (now KWSU) in
1922, one of the first radio stations in
the country
Examples of programming
Variety shows
Soap operas
Pretty much everything
we get on TV today
Fibber McGee and Molly
Burns and Allen
Fred Allen
Abbott and Costello
Orson Welles - 1938
Hindenburg disaster - 1937
Edward R. Murrow
The Advent of
It was assumed that radio would be dead
Audiences would watch TV instead of listening to
the radio
 TV took over so many of the radio programs
Soap operas
 Dramas
 Sitcoms
 Sports
 news
Radio had a great
advantage over TV –
Take it anywhere
Even in the car
New kinds of programming
Top 40
 Country
 Rock
 Easy listening
 Golden oldies
Talk shows
Howard Stern
On the Right
Rush Limbaugh Michael Savage Glenn Beck
On the Left
Ed Schultz
Stephanie Miller
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