Vol. DIY Electronics Projects
Chapter 5 Discrete Semiconductor Circuit Projects

Si Lab - Intro to Discrete Semiconductor Circuits

In these hands-on semiconductor electronics experiments, learn to build and test circuits using discrete silicon (Si) devices, including diodes and transistors. Also, learn important circuit designs, including rectifiers, current mirrors, amplifiers, and oscillators.

A semiconductor device is one made of silicon or any number of other specially prepared materials designed to exploit the unique properties of electrons in a crystal lattice, where electrons are not as free to move as in a conductor but are far more mobile than in an insulator.

Most of the semiconductor devices we encounter today are integrated circuits (ICs) which may contain thousands, millions, or even billions of transistors in a single package. A discrete device is one contained in its own package. The discrete semiconductor devices we will use in these projects are individual diodes and transistors, each in its own package.

Thus, discrete semiconductor circuits are circuits built out of individual semiconductor components, connected together on some kind of circuit board or terminal strip. As an example, in the simple op amp circuit, illustrated in Figure 1, there are six discrete bipolar junction transistors (BJTs) used to construct this circuit on a breadboard.


Simple op amp built using discrete bipolar junction transistors.

Figure 1. Simple op amp built using discrete BJTs.


We can learn a lot about semiconductors by building and testing these discrete circuits. These circuits in this chapter employ some of the components and concepts explored in the previous chapters, so a basic understanding of DC and AC electricity is helpful but not required before embarking on these experiments.

Just for fun, one circuit is included in this section using a vacuum tube for amplification instead of a semiconductor transistor. Before the advent of transistors, vacuum tubes were the workhorses of the electronics industry and. were used to make rectifiers, amplifiers, oscillators, and many other circuits. Though now considered obsolete for most purposes, there are still some applications for vacuum tubes, and it can be fun building and operating circuits using these devices.

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