Practical Electronics: Components and Techniques

Chapter 11. Logic

In electronics, the term logic generally means a circuit of some type that implements a logical function. The logic circuit might employ some relays, as shown in Chapter 10. Or it might consist of multiple small- and medium-scale ICs containing logic components, such as gates or flip-flops. It can be as simple as a couple of transistors and some diodes, or as complex as a modern CPU with billions of circuit elements.

The study of digital logic can, and does, fill entire textbooks (some of which are listed in Appendix C), but the primary emphasis in this chapter will be on the actual physical components.

We’ll start with a look at the building blocks of digital logic in the form of TTL and CMOS ICs. We’ll also take a quick look at programmable logic, microprocessors, and microcontrollers. The chapter wraps up with an introduction to logic probes and other techniques for testing logic circuits, as well as some tips for working with digital logic components.

Refer to Chapter 9 for a description of the package types used with logic devices. Chapter 4 shows some techniques for soldering ICs to circuit boards, and Chapter 15 discusses printed circuit board layout considerations for logic devices.

There is no way that the various families of available logic devices can be adequately covered in just a single chapter. For example, a typical data book from a manufacturer of digital logic devices is a thick tome with anywhere from 400 to 800 pages. And that can be for just ...