What is Switches

Chapter Switches

Complete Electronics Self Teaching Guide with Projects
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Complete Electronics Self Teaching Guide with Projects

  • CHAPTER 1 DC REVIEW AND PRETEST30SWITCHES31  A mechanical switch is a device that completes or breaks a circuit. The most familiar use is that of applying power to turn a device on or off. A switch can also permit a signal to pass from one place to another, prevent its passage, or route a signal to one of several places.In this book, you work with two types of switches. The first is the simple on-off switch, also called a single pole single throw switch. The second is the single pole double throw switch. Figure 1.11 shows the circuit symbols for each.ON-OFF switchSingle pole double throwor SPDT switchin the OFF positionFIGURE 1.11Keep in mind the following two important facts about switches: ■ A closed (or ON) switch has the total circuit current flowing through it. There is no voltage drop across its terminals. ■ An open (or OFF) switch has no current flowing through it. The full circuit volt-age appears between its terminals.The circuit shown in Figure 1.12 includes a closed switch.10 V+−10ΩABFIGURE 1.12QUESTIONSA. What is the current flowing through the switch? Book Authorc01V107/04/2012 2:44 PM c01.indd 307/4/2012 2:44:53 PM