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TRANSISTOR
I.
Introduction
It is amazing to know how our brain works. It could do
multiple tasks for every single second of our life. Because of its very complex
work, it comprises billions of brain cells which are known as neurons. In the world
of technology, computers are associated to our brain in which behind its
operation is also billions of electrical components that work together. These
are resistors, capacitors and transistors. Since we have learned already about
the first two electrical components, we will now study about transistors.
Transistor is a three-leg electrical component that makes
it unique from the rest. It functions as an amplifier or a switch. It is a bipolar junction which consists of
three layers of doped semiconductor which is usually made of silicon and is
even considered as the fundamental composition of integrated circuit.
II.
Parts
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As mentioned earlier, a transistor has three legs. To
understand the function of the three legs, let’s associate it with a faucet. In
a faucet, there is the path where water enters and leaves though it is somehow
just a one path. As observe in the faucet, there is a valve that controls the
volume of water that will flow.
III.
Types
A.
Bipolar Junction Transistor
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A.1. Types of Bipolar Junction
Transistor
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b. PNP. This is the opposite of NPN. This consists of two p-type semiconductors and one n-type separating the two. In this type, the electrons are the minority current carrier. Hence, the holes are the major current carrier of it.
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B.
Field Effect Transistor
1. a. JFET has lesser impedance than MOSFET.
1. b. MOSFET has higher impedance than JFET.
This has other names of its three legs or regions
which are gate, source and drain. If BJTs are current-controlled devices, FETs,
on the other way around are voltage-controlled devices. It means that a voltage
applied in the gate controls the flow of current from the source to the drain
regions. FETs have high impedance causing little current through it making it
to produce less amplification than the BJT. But the good thing here is it can
cause less loading in the circuit compared to BJT and they are considered to be
cheaper and easy to make.
C.
Other types according to Function
C.1.
Small Signal Transistors are preferable to use in amplifying low-level signals
which also functions as switches.
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C.2. Small Switching Transistors are primarily made as switches but can also be used as amplifiers but not as capable as the small signal transistor.
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C.3. Power Transistors are best used when large values of current and voltage are used. These come in NPN and PNP forms.
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IV.
Functions
1.
Amplifier. Small amount of current enters to one
leg and as it leaves, it becomes bigger current. In other words, it multiplies the
input current. In this case, common applications are hearing aids, microphone
and speakers.
2.
Binary switch. Same manner in amplification
where small amount of current flows in one part and it becomes bigger as it
flows to the other part. These small current will switch on the bigger one. So
in a microchip, billions of transistors can be switched on and off and these
san store two numbers, zero for off and one for on. All transistors can store
different numbers or letters individually that are known as characters.
V.
References
Retrieved on October 31, 2015 at http://whatis.techtarget.com/definition/transistor
Retrieved on October 31, 2015 at http://hyperphysics.phy-astr.gsu.edu/hbase/solids/trans.html
Retrieved on October 31, 2015 at http://www.technologystudent.com/elec1/transis1.htm
Retrieved on October 31, 2015 at http://boysdad.com/archives/3633
Retrieved on October 31, 2015 at http://www.learningaboutelectronics.com/Articles/Types-of-transistors.php
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