1.
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.
1.
Type
of transistor?
There are many types of transistors in use. Each
transistor is specialized in its application. The main classification is as
follows.
Bipolar Junction Transistor
A Bipolar junction transistor, shortly termed
as BJT is called so as it has two PN junctions for its
function. This BJT is nothing but a normal transistor. It has got two types of
configurations NPN and PNP. Usually NPN transistor is
preferred for the sake of convenience.
The types of BJT are NPN and PNP
transistors. The NPN transistor is made by placing a ptype material between two
n-type materials. The PNP transistor is made by placing an ntype material
between two p-type materials.
BJT is a current controlled
device. A normal transistor which we had discussed in the previous chapters
come under this category. The functionality, configurations and applications
are all the same.
Field Effect Transistor
An FET is a three-terminal
unipolar semiconductor device. It is a voltage
controlled device unlike a bipolar junction transistor. The main
advantage of FET is that it has a very high input impedance, which is in the
order of Mega Ohms. It has many advantages like low power consumption, low heat
dissipation and FETs are highly efficient devicesThe
FET is a unipolar device, which means that
it is made using either p-type or n-type material as main substrate. Hence the
current conduction of a FET is done by either electrons or holes
3. Transistor
test and identify?
4.Application
of transistor?
1.
A transistor is really
simple—and really complex. Let's start with the simple part. A transistor is a
miniature electronic component that can do two different jobs. It can work
either as an amplifier or a switch:
2.
When it works as an
amplifier, 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. That comes in really useful in
things like hearing aids , one of the first things people used transistors for.
A hearing aid has a tiny microphone in it that picks up sounds from the world
around you and turns them into fluctuating electric currents. These are fed
into a transistor that boosts them and powers a tiny loudspeaker, so you hear a
much louder version of the sounds.
3.
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). More about this in a moment.
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