A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is the fundamental building block of modern electronic devices, and is ubiquitous in electronic systems following its development in 1947.

Emmett Brown mentioned in his letter — written in 1885 and delivered to Marty McFly in 1955 via several generations of Western Union — that suitable parts for repairing the DeLorean time machine would not be available until 1947, the year the transistor was invented.

In 2015, a Magnavox Weekender AM-62 transistor radio was available for sale at the Blast from the Past antique/memorabilia store.

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