Solution:

An Analog System:

• A public address system, used to amplify sound so that it can be heard by a large audience, is one simple example of an application of analog electronics.

• The basic diagram in Figure illustrates that sound waves, which are analog in nature, are picked up by a microphone and converted to a small analog voltage called the audio signal.

• This voltage varies continuously as the volume and frequency of the sound changes and is applied to the input of a linear amplifier.

• The output of the amplifier, which is an increased reproduction of input voltage, goes to the speaker(s).

• The speaker changes the amplified audio signal back to sound waves that have a much greater volume than the original sound waves picked up by the microphone.

A System Using Digital and Analog Methods:

• The compact disk (CD) player is an example of a system in which both digital and analog circuits are used.

• The simplified block diagram in Figure illustrates the basic principle. Music in digital form is stored on the compact disk.

• A laser diode optical system picks up the digital data from the rotating disk and transfers it to the digital-to-analog converter (DAC).

• The DAC changes the digital data into an analog signal that is an electrical repro?duction of the original music. This signal is amplified and sent to the speaker for you to enjoy.

• When the music was originally recorded on the CD, a process, essentially the reverse of the one described here, using an analog-to-digital converter (ADC) was used.