The transistor radio was invented in 1947. It allowed people to carry radios with them.

The transistor revolution: how transistors changed the world

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In the internet age, radio still rules the world, Science and Technology News

Who Invented the Transistor Radio? Discover the Origins

The Transistor Radio Nuts & Volts Magazine

Who Invented the Transistor Radio? Discover the Origins

Groovy History

Transistor radio - Wikipedia

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Dec. 23, 1947: Transistor Opens Door to Digital Future