Radio

*Warning* Heavy Science Content Ahead

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 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 Believed everything contained electricity Looked for “animal magnetism” Touched different metals to frogs’ legs which twitched

Alessandro Volta

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 electicity

Hans Christian Oersted

Oersted’s experiment 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 needle 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 needle

Imagine his surprise when the needle swung the moment he turned on the current Imagine his surprise when the needle swung the moment he turned on the current He demonstrated that electricity created a magnetic field He demonstrated that electricity created a magnetic field

William Sturgeon Created the first electromagnet by wrapping wire around a soft iron bar and sending a current through the wire Electricity can create magnetism

Michael Faraday Reversed Sturgeon’s experiment Showed that magnetism could create an electric current

Samuel F. B. Morse

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

Examined physical sensations Examined physical sensations Can you feel colors Can you feel colors Can you hear shapes Can you hear shapes Can you smell sounds Can you smell sounds Discovered that each sense detects different things Discovered that each sense detects different things We think this is obvious, but no one had proven it before. Remember “common sense”? We think this is obvious, but no one had proven it before. Remember “common sense”?

Herman Hemholtz

Meuller’s pupil Meuller’s pupil Investigated hearing Investigated hearing Noticed sound produced vibrations Noticed sound produced vibrations

Did the vibrations operate at different frequencies? Did the vibrations operate at different frequencies? They did They did Thus, sound traveled at different frequencies Thus, sound traveled at different frequencies Used an electromagnet to attract the arms of a tuning fork, causing it to vibrate and produce sound Used an electromagnet to attract the arms of a tuning fork, causing it to vibrate and produce sound

Leon Scott de Martinville - phonautograph 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 glass

The Telephone Scott’s membrane, Faraday’s electromagnet, Oersted’s and Sturgeon’s electromagnet, Morse’s wire and electrical current, Heimholtz’s vibration, Scott’s membrane 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

Hemholtz’s pupil Hemholtz’s pupil Investigated whether electricity traveled in frequencies the way sound did 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

Marconi radio

Morse key

Marconi and his radio

Nikola Tesla

Tesla coil Developed the first amplifier coil, the Tesla coil Developed the first amplifier coil, the Tesla coil Raised the voltage of an electrical current high enough to allow the air to conduct the current Raised the voltage of an electrical current high enough to allow the air to conduct the current Key to wireless transmission of radio waves Key to wireless transmission of radio waves

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 signal 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 signal Did the first voice broadcast in 1900 Did the first voice broadcast in 1900 Short range Short range Poor quality Poor quality Needed far more power 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 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 In Dec. 1906, Fessenden did the first good voice and music broadcast, going hundreds of miles Poetry and a Bible reading Poetry and a Bible reading A woman singing opera A woman singing opera A violin playing a Christmas carol A violin playing a Christmas carol

Lee de Forest

The audion tube is actually a Fleming valve (British term for tube) invented in England The audion tube is actually a Fleming valve (British term for tube) invented in England de Forest simply added the bent wire de Forest simply added the bent wire

De Forest’s audion tube

Audion tube amplified the radio signal the way the Alexanderson generator increased the electrical power Audion tube amplified the radio signal the way the Alexanderson generator increased the electrical power de Forest didn’t know how the audion worked de Forest didn’t know how the audion worked Another man did Another man did

Edwin Howard Armstrong

Investigated the audion tube, figured out how it worked, and improved it Investigated the audion tube, figured out how it worked, and improved it Developed “regeneration” Developed “regeneration” The signal was fed back into the tube over and over again, up to 20,000 times a second 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 Vastly increased the power of the tube to output the signal – it was an amplifier Raise the level enough and the tube becomes a transmitter Raise the level enough and the tube becomes a transmitter Armstrong invented the ability to broadcast sound 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 sensitivity It combined high frequency waves with low frequency waves, then fed them back into the system to amplify the signal and increase its sensitivity Resulted in the creation of the home, and the portable, radio Resulted in the creation of the home, and the portable, radio

Armstrong’s superheterodyne Armstrong’s next invention was the superheterodyne Armstrong’s next invention was the superheterodyne

Crystal Radio

David Sarnoff

Enamored of radio Enamored of radio Saw the possibilities Saw the possibilities Wrote the “Radio Music Box Memo” that outlined the commercial possibilities of radio Wrote the “Radio Music Box Memo” that outlined the commercial possibilities of radio

RCA (Radio Corporation of America) After World War I After World War I Four companies merged their patents to create RCA Four companies merged their patents to create RCA American Marconi American Marconi General Electric General Electric American Telephone & Telegraph American Telephone & Telegraph Westinghouse Westinghouse Sarnoff named as commercial manager 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 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

student

Examples of programming Operas Operas Concerts Concerts Sports Sports News News Dramas Dramas Comedies Comedies Variety shows Variety shows Soap operas Soap operas Pretty much everything we get on TV today

Fibber McGee and Molly

Burns and Allen

Fred Allen

Abbott and Costello

Orson Welles

Hindenburg disaster

Edward R. Murrow

The Advent of Television

It was assumed that radio would be dead It was assumed that radio would be dead Audiences would watch TV instead of listening to the radio Audiences would watch TV instead of listening to the radio TV took over so many of the radio programs TV took over so many of the radio programs Soap operas Soap operas Dramas Dramas Sitcoms Sitcoms Sports Sports news news

Radio had a great advantage over TV – Portability

Take it anywhere

Even in the car

New kinds of programming Music Music Top 40 Top 40 Country Country Rock Rock Easy listening Easy listening Golden oldies Golden oldies Talk shows Talk shows

Howard Stern

On the Right Rush Limbaugh Michael Savage Glenn Beck

On the Left Ed Schultz Stephanie Miller