Digital electronics

We see the digits 0 to 9 on an electronic calculator or digital watch, but digital electronics has a much broader meaning. The circuits for digital applications operate with pulses of voltage or current, as shown in figure (a). A pulse waveform is either completely ON or OFF because of the sudden changes in amplitude. In between values have no function. Note that the ON and OFF states can also be labeled HIGH or LOW, or 1 and 0 in binary notation, which uses only two digits. Effectively, the digital pulses correspond to the action of switching circuits that are either ON or OFF.

Actually, all the possible variations in types of electronic circuits can be divided into just two types-digital circuits that recognize pulses when they are HIGH or LOW, and analog circuits that use all values in the waveform. The applications of digital electronics, including calculators, computers, processing, and data communications, possibly the biggest branch of electronics. Many other applications, including radio and television, use both analog and digital circuits. Analog-to-digital (A/D) converters in change the signal from one form to the other.

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Electric power

These applications are in the generation and distribution of 60-Hz ac power, as the source of energy for electrical equipment. Included are lighting, heating, motors, and generators.

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Communications electronics

This field includes AM radio, FM radio with stereo, and television with color. The equipment is divided between transmitters and receivers. Also, transmitters can be divided between radio-frequency equipment to produce the carrier wave radiated from the antenna and the audio and video equipment in the studio that supplies the modulating signal with the desired information. high-fidelity audio equipment can be considered with radio receivers. The receiver itself has audio amplifiers to drive the loudspeakers that reproduce the sound. Satellite communications is also a transmit-receive system using electromagnetic radio waves. The satellite just happens to be orbiting around the earth at a height of above 22,000 miles in order to have a tremendous field of view. Actually, the satellite is a relay station for transmitter and receiver earth stations.

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