The transistor is a typical electronics component. Actually it gave electronics a justification. This is divided into two parts, the somewhat older analogue- and the newer digital technology. The transistor as a component is found in both. In the analogue technology it is also more often used as an amplifier, e.g., in transistor radios. It is however, particularly important for the digital field, where it works mostly as a switch.
Has become very rare: components with individual transistors
Compared with the working current relay, the transistor is not only much quicker, it also has - if correctly fitted into the circuit - an almost limitless service life. Unfortunately, however, if you compare the working current it's effectivity is lower, which can very often be seen in the high heat development and the, often necessary, cooling elements. Another important point is also, that a transistor, as opposed to a relay, makes a perfect galvanic separation between the working- and the controling cycle impossible.
NPN: Collector and base positive, emitter (more) negative. PNP: Collector and base negative, emitter (more) positive.
The semi-conductor consists of one single crystal, made mostly from silicon or (more rarely) germanium. The crystal contains at least two zones of differing conductivity, thus it can be compared to a double array of diodes. The lattice construction, and with it, the conductivity can, through the addition of certain metals (e.g. arsenic or antimony) be differently influenced in it's layers. The arrangement of the layers is marked by the letters NPN or PNP. If the basis (middle letter) is negative, their connection with the negative pole of an (identical) power source can improve the conductivity between the other two, the emitter and the collector. The opposite is valid for the NPN-transistor. A transistor can be used as a switch or as an amplifier. In integrated circuits (ICs) it is used as a surface- or planar transistor. Computer technology is based, to a large extent, on transistors. In modern storage- und microprozessor-chips more than one million transistors can be found on an area no bigger than a postage stamp.
Where it's name comes from
The expression "transistor" was coined from an artificial word made up from "transfer resistor", which indicates the transfer of changes in resistance from one interface to another. 11/10
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