Page 117 - Testing Electronic Components

Testing Transistor

Transistors are solid –state devices similar in some way to the diodes you
have studied. Transistors are more complex and can be used in many
more ways. They are very important and can be found in almost all
modern electronic equipment. The name transistor is derived from “trans
resistor”, meaning that it changes resistance. Unlike a diode, a transistor
has three leads. The three transistor leads are designated as Base (B),
Collector (C), and Emitter (E).

There are two configurations for a common transistor: NPN and PNP as

shown in Figure 1. Notice the difference symbols for NPN and PNP
transistor. The emitter arrow points away from the transistor body for an
NPN and toward the transistor body for PNP.

Fig 1 : The circuit symbols for the two transistor types a) NPN b) PNP

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