tailieunhanh - Ebook Teach yourself electricity and electronics (4th edition): Part 2
(BQ) Part 2 book "Teach yourself electricity and electronics" has contents: Introduction to semiconductors, power supplies, the bipolar transistor, amplifiers and oscillators, wireless transmitters and receivers, integrated circuits, electron tubes, a computer and internet primer, personal and hobby wireless,.and other contents. | 3 PART Basic Electronics Copyright © 2006, 2002, 1997, 1993 by The McGraw-Hill Companies, Inc. Click here for terms of use. This page intentionally left blank 19 CHAPTER Introduction to Semiconductors SINCE THE 1960S, WHEN THE TRANSISTOR BECAME COMMON IN CONSUMER DEVICES, SEMICONDUCTORS have acquired a dominating role in electronics. The term semiconductor arises from the ability of these materials to conduct some of the time, but not all the time. The conductivity can be controlled to produce effects such as amplification, rectification, oscillation, signal mixing, and switching. The Semiconductor Revolution Decades ago, vacuum tubes, also known as electron tubes, were the only devices available for use as amplifiers, oscillators, detectors, and other electronic circuits and systems. A typical tube (called a valve in England) ranged from the size of your thumb to the size of your fist. They are still used in some power amplifiers, microwave oscillators, and video display units. Tubes generally require high voltage. Even in modest radio receivers, 100 V to 200 V dc was required when tubes were employed. This mandated bulky power supplies, and created an electrical shock hazard. Nowadays, a transistor of microscopic dimensions can perform the functions of a tube in most situations. The power supply can be a couple of AA cells or a 9-V transistor battery. Even in high-power applications, transistors are smaller and lighter than tubes. Figure 19-1 is a size comparison drawing between a transistor and a vacuum tube for use in an AF or RF power amplifier. Integrated circuits (ICs), hardly larger than individual transistors, can do the work of hundreds or even thousands of vacuum tubes. An excellent example of this technology is found in personal computers and the peripheral devices used with them. 19-1 A power-amplifier transistor (at left) is much smaller than a vacuum tube of comparable powerhandling capacity (right). 315 Copyright © 2006, 2002, 1997, 1993
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