Lesson Notes By Weeks and Term v4 - SHS 2
ELECTRONIC COMPONENTS AND CIRCUITS
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ELECTRONIC COMPONENTS AND CIRCUITS
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Subject: Applied Technology
Class: SHS 2
Term: 2nd Term
Week: 18
Grade code: 2.5.2.LI.6
Strand code: 5
Sub-strand code: 2
Content standard code: 2.5.2.CS.1
Indicator code: 2.5.2.LI.6
Theme: ELECTRICAL AND ELECTRONIC TECHNOLOGY
Subtheme: ELECTRONIC COMPONENTS AND CIRCUITS
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Welcome, learners. In our last lesson, we looked at semiconductor diodes. Today, we are moving on to one of the most important inventions of the 20th century: the transistor. Look around you. Your mobile phone, the radio you listen to, the television in your hall, and even the simple calculator you use – all of them contain millions or even billions of tiny electronic switches called transistors. They are the building blocks of modern electronics. Understanding how they work is fundamental to understanding almost any electronic device you use in your daily life in Ghana.
What is a Transistor? A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. Think of it like a water tap (*bɔɔla*). A small turn of the handle (a small input signal) can control a large flow of water (a large output current).
There are two main families of transistors we will study: Bipolar Junction Transistors (BJT) Field Effect Transistors (FET) We will also look at a special type called the Unijunction Transistor (UJT).
A. Bipolar Junction Transistors (BJT) The name "Bipolar" means that its operation involves two types of charge carriers: electrons and holes. BJTs are current-controlled devices, meaning a small input current controls a large output current.
A BJT is made of three layers of semiconductor material. It has three terminals: Emitter (E): Emits or sends charge carriers. It is heavily doped. Base (B): Controls the flow of charge carriers. It is very thin and lightly doped. Collector (C): Collects the charge carriers. It is the largest of the three sections.