Advanced Search




Transistors are electronic components. A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power similar to a vacuum tube. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A transistor can control its output in proportion to the input signal. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. The essential usefulness of a transistor for computers comes from its ability to turn current on or off in a circuit as an electrically controlled switch, where the amount of current is determined by other circuit elements. Transistors are commonly used as electronic switches, both for high-power applications such as switched-mode power supplies and for low-power applications such as logic gates. In any switching circuit, values of input voltage would be chosen such that the output is either completely off, or completely on. The transistor is acting as a switch, and this type of operation is common in digital circuits where only "on" and "off" values are relevant.
Following its development in the early 1950s, the transistor revolutionized the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, among other things. The transistor is the key active component in practically all modern electronic devices. Its importance in today's society rests on its ability to be mass produced using a highly automated process that achieves astonishingly low per-transistor costs. Although several companies each produce over a billion individually packaged (known as discrete) transistors every year, the vast majority of transistors now are produced in integrated circuits (often shortened to IC, microchips or simply chips), along with diodes, resistors, capacitors and other electronic components, to produce complete electronic circuits. The transistor's low cost, flexibility, and reliability have made it a ubiquitous in modern electronic devices such as computers. In most applications transistors have replaced vacuum tubes.

Electronic logic gates can be build with transistors. A transistor logic gate consists of about twenty transistors whereas an advanced microprocessor employed in modern computers can use as many as 3 billion transistors. The Z23 was the first computer developed by Konrad Zuse's company that utilized transistors and all following computer models such as the Z31 used this technology.

Transistorized mechatronic circuits have replaced electromechanical devices in controlling appliances and machinery. It is often easier and cheaper to use a standard microcontroller and write a computer program to carry out a control function than to design an equivalent mechanical control function.

cf. Wikipedia