Editing AM broadcasting (section)

===Receivers===
[[File:Vintage Zenith Console Radio, Model 12S-568, With the Zenith Robot (or Shutter) Dial, Circa 1941 (8655513293).jpg|thumb|1938 Zenith Model 12-S vacuum-tube console radio, capable of picking up mediumwave and shortwave AM transmissions. "All Wave" receivers could also pick up the third AM band: longwave (LW).]]
Unlike telegraph and telephone systems, which used completely different types of equipment, most radio receivers were equally suitable for both radiotelegraph and radiotelephone reception. In 1903 and 1904 the [[electrolytic detector]] and [[thermionic diode]] ([[Fleming valve]]) were invented by [[Reginald Fessenden]] and [[John Ambrose Fleming]], respectively. Most important, in 1904–1906 the [[crystal detector]], the simplest and cheapest AM detector, was developed by [[Greenleaf Whittier Pickard|G. W. Pickard]]. Homemade [[crystal radio]]s spread rapidly during the next 15 years, providing ready audiences for the first radio broadcasts. One limitation of crystals sets was the lack of amplifying the signals, so listeners had to use [[earphone]]s, and it required the development of vacuum-tube receivers before [[loudspeaker]]s could be used. The [[Loudspeaker|dynamic cone loudspeaker]], invented in 1924, greatly improved audio [[frequency response]] over the previous horn speakers, allowing music to be reproduced with good fidelity.<ref name="McNicol13">{{Cite web|url=http://archive.org/details/radiosconquestof00mcnirich|title=Radio's conquest of space|first=Donald Monroe|last=McNicol|date=August 11, 1946|publisher=New York : Murry Hill|via=Internet Archive}}</ref> AM radio offered the highest sound quality available in a home audio device prior to the introduction of the [[high-fidelity]], [[long-playing]] record in the late 1940s.

Listening habits changed in the 1960s due to the introduction of the revolutionary [[transistor radio]] (Regency TR-1, the first transistor radio released December 1954), which was made possible by the invention of the [[transistor]] in 1948. (The transistor was invented at Bell labs and released in June 1948.) Their compact size — small enough to fit in a shirt pocket — and lower power requirements, compared to vacuum tubes, meant that for the first time radio receivers were readily portable. The transistor radio became the most widely used communication device in history, with billions manufactured by the 1970s. Radio became a ubiquitous "companion medium" which people could take with them anywhere they went.