Hobbies And Interests
Amplifier Classes
Electronic engineers have divided amplifier designs into classes denoted by letters, where class A has the best accuracy, but lowest efficiency, class B has better efficiency but slightly less fidelity, and so on. Inefficient amplifiers consume more power and produce more heat than efficient ones; at high power levels, managing the heat becomes a problem. Generally, linear amplifiers are class A or AB, AB being midway between A and B for efficiency and accuracy.
Signal Response
Ideally, the signal an amplifier produces at its output is a perfect duplicate of the input signal, though having taller current or voltage peaks. A sine wave input, for example, produces an output with a smooth and continuous shape from negative peak to positive peak, with no flattening or other distortions. In practice, even the best amplifiers produce some distortion; the goal is to keep it as small as possible. Linear amplification is defined as a linear, proportional relation between corresponding points of the amplifier̵7;s input and output signals. Nonlinear amplifiers have non-proportional signal responses, flattening a signal̵7;s peaks or introducing sudden transitions in the wave shape.
Radio Transmitter
An amateur or commercial radio transmitter that uses amplitude modulation, or AM, has a linear amplifier. AM radio works by superimposing the waves produced by voice or music on the amplitude ̶0;envelope̶1; of a higher-frequency signal, called a carrier. The carrier wave takes on the appearance of an accordion bellows, stretching and compressing from the program content. Because the strength of the carrier signal varies, depending on the signal being broadcast, the amplifier needs to respond to these changes accurately. If the amplifier distorts the signal, it degrades the sound coming from the radio receiver.
Audio Amplifier
Because of the low efficiency of class A amplifiers, few radios, entertainment centers and musical instrument amplifiers are of this type. Instead, most are class AB, whose efficiency is better than A with nearly the same accuracy. Class AB amplifiers have a more components and a more complex design than an Class A, which uses a single transistor or vacuum tube for amplification. Class B and C designs, while being more efficient, have poor signal accuracy for audio applications, though may see use in public address systems, bull horns and other uses where loudness is more important than high fidelity.