TC 9-62
Figure 2-1. Assortment of Different Types of Transistors
2-2.
Transistors are used in many areas of science and industry (from the family car to
satellites). The military depends heavily on transistors. The ever-increasing uses for
transistors have created an urgent need for sound and basic information regarding their
operation.
2-3.
After learning about the PN junction diode in chapter 1, you should have the basic
knowledge on how to grasp the principles of transistor operation. This chapter will discuss
the basic types of transistors, their construction, and their theory of operation. It also
discusses how and why transistors amplify. This chapter also covers transistor terminology,
capabilities, limitations, and identification; transistor maintenance; ICs; circuit boards; and
modular circuitry.
TRANSISTOR FUNDAMENTALS
2-4.
The first solid state device covered in chapter 1 was the two-element
semiconductor diode. The next device we will cover not only has one more element than
the diode but it can amplify as well. Semiconductor devices that have three or more
elements are called TRANSISTORS. The term transistor was derived from the words
TRANSFER and RESISTOR. This term was adopted because it best describes the
operation of the transistor. The operation of the transistor is the transfer of an input signal
current from a low-resistance circuit to a high-resistance circuit. The transistor is basically
a solid state device that amplifies by controlling the flow of current carriers through its
semiconductor materials.
2-5.
There are many different types of transistors, but their basic theory of operation is
the same. The theory we will use to explain the operation of a transistor is the same theory
used earlier with the PN junction diode. The exception is that now two such junctions are
required to form the three elements of a transistor. The three elements of the two-junction
transistor are as follows:
2-2
TC 9-62
23 June 2005
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