BJT
Science & Engineering abbreviation · Electronics & Electrical
| Stands for | Bipolar junction transistor |
|---|---|
| Categories | Science & Engineering |
BJT stands for Bipolar junction transistor, an electronics & electrical abbreviation.
Transistor made of three layers of doped semiconductor, either NPN or PNP, in which a small current into the base controls a larger current between collector and emitter. BJTs are used as amplifiers and switches, especially in analog circuits.
Example: A 2N2222 BJT switches the relay coil when the microcontroller drives its base through a 1 kilohm resistor.
Usage notes
John Bardeen and Walter Brattain built the point-contact transistor at Bell Labs in December 1947, and William Shockley invented the junction transistor in 1948; the three shared the 1956 Nobel Prize in Physics. A silicon BJT's base-emitter junction turns on at roughly 0.6-0.7 volts. In digital electronics MOSFETs have largely replaced BJTs.
Related abbreviations
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