- A transistor is an electronic component used in a circuit to control a large amount of current or voltage with a small amount of voltage or current.
- When a third doped element is added to a crystal diode in such a way that two pn junctions are formed, the resulting device is known as a transistor. The transistor—an entirely new type of electronic device - is capable of achieving amplification of weak signals in a fashion comparable and often superior to that realized by vacuum tubes
- Transistor consists of two pn junctions formed by sandwiching either p-type or n-type semiconductor between a pair of opposite types. Accordingly; there are two types of transistors, namely;
(i) n-p-n transistor (ii) p-n-p transistor
An n-p-n transistor is composed of two n-type semiconductors separated by a thin section of ptype as shown in Fig. 4.1 (i). However, a p-n-p transistor is formed by two p-sections separated by a thin section of n-type as shown in Fig. 4.1 (ii).
In each type of transistor, the following points may be noted:
(i) These are two pn junctions. Therefore, a transistor may be regarded as a combination of two diodes connected back to back.
(ii) There are three terminals, one taken from each type of semiconductor.
(iii) The middle section is a very thin layer. This is the most important factor in the function of a transistor.
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Origin of the name ?Transistor?. When new devices are invented, scientists often try to devise a name that will appropriately describe the device. A transistor has two pn junctions. As discussed later, one junction is forward biased and the other is reverse biased. The forward biased junction has a low resistance path whereas a reverse biased junction has a high resistance path. The weak signal is introduced in the low resistance circuit and output is taken from the high resistance circuit. Therefore, a transistor transfers a signal from a low resistance to high resistance. The prefix =trans‘ means the signal transfer property of the device while =istor‘ classifies it as a solid element in the same general family with resistors.
lendiritu answered the question on
November 30, 2017 at 07:00