Starting Electronics, 4th Edition

Chapter 8. Transistors

Transistors are introduced in this chapter. The transistor is formed by two PN junctions of semiconductors ie, effectively two back-to-back diodes. The three terminals of a transistor—the emitter, collector, and base—are named. Two main types of transistor, created by the two ways a pair of PN junctions can be joined, are shown: NPN and PNP transistors. A small base current is shown to create a large collector current, which means that a transistor is effectively a current amplifier. Two main operating modes of transistors are discussed: analog, and digital. Transistors operating in analog mode have outputs that vary over a range of voltages. Transistors in digital mode merely act as switches.

Keywords: Transistor, PN junction, ...