2. Radio Days, Continued

The first commercial car radios arrived in the early 1930s, though enthusiasts had built their own solutions before then. The Galvin Manufacturing Corporation launched their "Motorola" radio in 1930 - "motor" for automobile and "ola" for sound - it was so successful that the company changed its name to that of the product in 1947. European manufacturers soon followed, with car audio giant Blaupunkt one of the first to market. Driving valve radios from a car's battery was a complex affair, and used a mix of low voltage from the battery and step up transformers to generate the required high voltages. Car radios remained AM only until the early 1950s, when Blaupunkt released their first FM systems.

Over time, the move to transistor allowed new features to be added, and new technologies to replace the original mechanical tuning dials. There have been some strange hybrid solutions along the way: Motorola once sold car radios that could play a 45 RPM record. Some enthusiasts even fitted reel-to-reel tape systems in their cars, but these were often impractical.

In 1956 Motorola produced its first transistor car radio: the 1958 catalog features the invention.

Out of the car, the invention of the transistor meant portable battery-powered radios, with the first devices appearing in the early 1950s, and commercial sales starting in 1954. Transistor radios ran off a single voltage, and soon became pocket-size. Receivers were initially only for AM, but they soon added support for higher-fidelity FM stations. The move to integrated circuits reduced power demands and size still further. Now stereo FM radios are a common component in all forms of portable media, from car radios to FM receivers in MP3 players.