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

Transistor radio - Wikipedia

The History of the Transistor Radio

Cold War archive: How the USSR and U.S. battled each other with radio waves - Russia Beyond

History of Early Solar Powered Radios • Museum Of Solar Energy

How the Transistor Radio with Music for Your Pocket Fueled a Teenage Social Revolution, At the Smithsonian

Who Invented the Transistor Radio? Discover the Origins

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

Let's Get Small SPARK Museum of Electrical Invention

Who invented the transistor radio? - Quora

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

Radio Broadcasting - New Georgia Encyclopedia

It's Sixty Years Since the First Portable Transistor Radio Went on the Market and Started a Revolution

Groovy History