In the circuits given here we use four transistors for the NPN version of the high gain transistor and four the the PNP one. By choosing the best values for R1, R3 and R4 the total current ...

“The Bipolar Junction Transistor (BJT, such as NPN and PNP) was invented by Bell Labs in 1947.” Not exactly. The transistor demonstrated by Bell Labs in ’47 was a point contact transistor.

NPN transistors are key components in electronics, used as switches or amplifiers with three legs: base, collector, and emitter. Thyristors are semiconductor switches with three legs: gate, anode ...