Electronics

Amplifiers are electronic devices that boost current, voltage, or power. Audio amplifiers are used in radios, televisions, cassette recorders, sound systems, and citizens band radios. They receive sound as electrical signals, amplify these, and convert them to sound in speakers. Video amplifiers increase the strength of the visual information seen on the television screen by regulating the brightness of the image-forming light. Radio frequency amplifiers are used to amplify the signals of communication systems for radio or television broadcasting and operate in the frequency range from 100 kHz to 1 GHz and sometimes into the microwave-frequency range. Video amplifiers increase all frequencies equally up to 6 MHz; audio amplifiers, in contrast, usually operate below 20 kHz. But both audio and video amplifiers are linear amplifiers that proportion the output signal to the input received; that is, they do not distort signals. Other forms of amplifiers are nonlinear and do distort signals usually to some cutoff level. Nonlinear amplifiers boost electronic signals for modulators, mixers, oscillators, and other electronic instruments.