An analog signal has continuous and varying value over any time interval, with infinite resolution in time and magnitude. A simple analog signal is a sine wave that is described using amplitude and time as shown in Figure 8.3:
Figure 8.3
Analog signals are used for control operations of analog devices, such as controlling the speed of a DC motor (a DC motor is an analog device). To change the speed of motor we simply vary the resistance in its current path due to which current available at motor changes and hence the speed.
Let's consider that we use a battery as a source of analog signal for controlling the speed of the motor. ...
