Editing Bipolar junction transistor (section)

=== Amplifiers ===
{{Main|Electronic amplifier}}

One of the most prominent early uses of the transistor was in consumer products such as the [[transistor radio]] which [[Regency TR-1|began production in 1954]]. The use of transistors in handheld radios and would also jumpstart a small Japanese company named Tokyo Tsushin Kogyo K.K. to prominence with its [[TR-55]] transistor radio bearing the name the company would soon change to match: [[Sony]]. The follow-on pocket-sized Sony TR-63 and several larger models by other manufacturers cemented the transistor and miniaturized electronics as critical to the new, portable consumer device market for decades to come.{{cn|reason=Need RS for "cemented the transistor and miniaturized electronics as critical to the new, portable consumer device market for decades to come"|date=June 2025}}

The [[#Transistor parameters: alpha (α) and beta (β)|transistor parameters]] α and β characterize the [[gain (electronics)|current gain]] of the BJT. It is this gain that allows BJTs to be used as the building blocks of electronic amplifiers. The three main BJT amplifier topologies are:
* [[Common emitter]]
* [[Common base]]
* [[Common collector]]