Practical Audio Electronics

15  |  Switches

Switches route, connect, and select electrical signals

The humble switch seems a trivially simple topic at first glance but there is much more to this versatile component than might be immediately apparent. In its most basic form it is indeed a very straightforward device; the function of a light switch or a doorbell buzzer is no more than to make and break a single electrical connection. This is achieved using what would be called a single pole single throw or spst switch. Poles and throws are two key concepts for switches, and a switch might have (in theory) any number of each – more on this later.

Figure 15.1 illustrates the three basic roles which a switch can play in the operation of an electrical circuit, as given in ...