Principles of Transistor Circuits, 9th Edition

Chapter 15

Digital circuits

Introduction

As mentioned in the previous two chapters, transistors in multivibrators and other pulse circuits are used as switches, i.e. except for the brief periods during which the transistors are changing state they are either on (taking considerable current) or off (non-conductive). For most of the time therefore the collector (or drain) voltage has one of two possible values namely a low value near emitter or source potential (when the transistor is on) and a high value near the supply potential (when the transistor is off).

A vast range of circuits has been developed during the past decade or two in which diodes and transistors are used as switches and in which the signal paths have at all times one or other of ...