Emergence of transistors became at the time the real revolution. And there is no wonder, the bulky electron tube was replaced tiny, in comparison with it, by semiconductor radioelement. Now transistors are still the major electronic components, use them as separately, and as a part of chips.
The physicist Walter Bratteyn and the theorist John Bardin are considered as creators of the first operable transistor, it has been tested by them in December, 1947. From now on also the era of transistors ‒ thanks to their emergence has begun has become possible to create the compact electronic equipment with low consumption of power.
As the transistor works
The main objective of the transistor is strengthening of signal. For example, the antenna of the detector radio receiver has caught signal of radio station. After detecting the sound can already be heard in earphones, but for conclusion to the big loudspeaker of power of the allocated signal is not enough. It needs to be strengthened, for this purpose and transistors are used.
The essence of operation of the transistor is that the weak signal arriving on one of transistor conclusions – base – modulates stronger signal arriving on the second conclusion of the transistor – the emitter. The strengthened signal is removed from the third conclusion of the transistor – the collector. In this case the base of the transistor can be compared to the crane installed on "pipe" the emitter collector on which there passes more heavy current. When on base together with bias voltage (it is necessary in order that the transistor has opened) the signal from the detector of the receiver is given, this weak signal it appears enough to operate current in more powerful chain. As a result from the collector just the same signal which has arrived on base, but much stronger is removed. How to be if the power of one transistor for strengthening is not enough? In this case just use several cascades of strengthening. In practice in the normal receiver of direct strengthening at first there is strengthening on high frequency, then the signal is detected – that is from it sound vibrations are allocated – and already they amplify in cascades of strengthening of low frequency. As a result in loudspeakers of the receiver the loud clear sound is heard.
Structure of the transistor
Bipolar transistors are the most widespread, they happen two types – p-n-p (positive-negative-positive) and n-p-n (negative-positive-negative). For production of p-n-p-transistors use the semiconductor of germaniye, and for n-p-n-transistors – silicon. In each such transistor there are two so-called electronhole junctions, they also allow to strengthen signal. Holes and electrons are charge carriers. In n-p-n-transistors the charge is transferred by electrons, and in p-n-p-transistors – holes. On base of the transistor the small displacement current moves, as a result the transistor opens. If now to modulate this displacement current useful signal, then the signal will be strengthened. There are also other types of transistors – for example, field. Thanks to various types of transistors it is possible to create the most various electronic equipment.