Electronics All-in-One For Dummies, 2nd Edition

Chapter 3

Working with Logic Circuits

IN THIS CHAPTER

Implementing logic gates with transistors

Looking at TTL and CMOS integrated circuits

Building some simple logic circuits

In Book 5, Chapter 2, you learn all about logic gates, including the seven most popular kinds of gates: NOT, AND, OR, NAND, NOR, XOR, and XNOR.

In this chapter, you learn how to create actual circuits that use logic gates. I start you off by showing you the basics of how logic gates can be created from simple transistor circuits. Then I look at two popular integrated circuit families that provide prebuilt logic gates.

If you haven’t already read Chapter 2, I suggest that you go back and do so now before you read this chapter. Little of this chapter will make sense if you aren’t familiar with the different types of gates described in that chapter.

Creating Logic Gates with Transistors

Way back in Book 2, Chapter 6, you see how transistors can be used as switches. In a nutshell, a voltage applied to the base of a transistor allows current to flow from the collector to the emitter. Thus, by applying an input signal to a transistor’s base, you can control an output signal taken from the collector-emitter path. ...