What is Transistor?
A transistor is a device that regulates current or voltage flow and acts as a switch or gate for electronic signals. Transistors consist of three layers of a semiconductor material, each capable of carrying a current.
The transistor was invented by three scientists at the Bell Laboratories in 1947, and it rapidly replaced the vacuum tube as an electronic signal regulator.
By three brilliant US physicists: John Bardeen (1908–1991), Walter Brattain (1902–1987), and William Shockley (1910–1989).
A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.
How transistor works?
Its works as an amplifier, when it takes in a tiny electric current at one end (an input current) and produces a much bigger electric current (an output current) at the other. In other words, it's a kind of current booster.
Transistors can also work as switches. A tiny electric current flowing through one part of a transistor can make a much bigger current flow through another part of it. In other words, the small current switches on the larger one. This is essentially how all computer chips work. For example, a memory chip contains hundreds of millions or even billions of transistors, each of which can be switched on or off individually. Since each transistor can be in two distinct states, it can store two different numbers, zero and one. With billions of transistors, a chip can store billions of zeros and ones, and almost as many ordinary numbers and letters (or characters, as we call them).
Types of Transistors.
There are a varieties and different types of transistors
available in today's market including Bipolar, Darlington, IGBT, and
MOSFET Transistors.
- Bipolar Transistor -
A Bipolar Junction Transistor (BJT) is a three-terminal electronic device made of doped semiconductor material and may be used in amplifying or switching applications. Bipolar transistors are so named because their operation involves both electrons and holes. A bipolar transistor will have terminals that are labeled: emitter, collector, base. A small current at the base terminal (passing from the base to the emitter) can modify or switch a much larger current between the collector and emitter terminals.
- Darlington Transistor - The Darlington Transistor is actually two bipolar transistors, connected in such a way that the current amplified by the first transistor is amplified even further by the second one. This model offers a higher common-emitter current gain than if both types of transistors are separated and can even take up less space because both transistors can share a collector.
- IGBT Transistor - An Insulated Gate Bipolar Transistor (IGBT) is a three-terminal power semiconductor device typically used as an electronic switch. IGBT's are types of transistors that are capable of switching electric power in many modern appliances such as electric cars, trains, variable speed refrigerators, air-conditioners and even stereo systems with switching amplifiers.
- MOSFET Transistor - A Metal-Oxide-Semiconductor Field-Effect Transistor (MOFET) is used in integrated circuits to control the conductivity of a channel. MOSFETs are highly dependent on negative and positive charges. They have many purposes, including limiting a device's power levels, storing data, and being used as a switch for a wide variety of electronic devices.
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