Lesson Notes By Weeks and Term v4 - SHS 1
ELECTRONIC DEVICES AND CIRCUITS
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
ELECTRONIC DEVICES AND CIRCUITS
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Applied Technology
Class: SHS 1
Term: 2nd Term
Week: 5
Grade code: 1.3.2.LI.3
Strand code: 3
Sub-strand code: 2
Content standard code: 1.3.2.CS.1
Indicator code: 1.3.2.LI.3
Theme: ELECTRICAL AND ELECTRONIC TECHNOLOGY
Subtheme: ELECTRONIC DEVICES AND CIRCUITS
This page supports the lesson note with a companion video and a short classroom-ready summary.
For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.
Welcome, future engineers and technicians! Today, we are exploring one of the most fundamental components in all of electronics: the diode. Think about your mobile phone charger. You plug it into the wall socket which supplies Alternating Current (AC), but your phone battery needs Direct Current (DC) to charge. How does this conversion happen? The magic begins with the diode. In Ghana, where our power supply can sometimes be unstable, understanding how to convert, clean, and regulate electricity is a very valuable skill. From building simple phone chargers to designing security systems for our homes, diodes are the gatekeepers that make modern electronics possible.
This section covers the essential knowledge you need to master the use of diodes. 2.1 What is a Diode?
A diode is a semiconductor electronic component that allows electric current to flow in only one direction. Think of it as a one-way street or a valve for electricity. Symbol: The arrow in the symbol points in the direction of conventional current flow. Terminals: Anode (A): The positive terminal where current enters. Cathode (K): The negative terminal where current leaves. It is usually marked with a silver or black band on the physical component. Biasing: Forward Bias: When the positive terminal of a voltage source is connected to the Anode and the negative terminal to the Cathode, the diode acts like a closed switch and allows current to flow. Reverse Bias: When the polarity is reversed (positive to Cathode, negative to Anode), the diode acts like an open switch and blocks current flow. 2.2 Types of Diodes and Their Functions
The NaCCA curriculum requires us to know several types. Let's explore them.
| Diode Type | Symbol | Primary Function & Explanation | Common Application | | :--- | :--- | :--- | :--- | | Rectifier Diode (Power Diode) | | To convert Alternating Current (AC) to Direct Current (DC). It is the main component in power supplies. It can handle higher currents and voltages than signal diodes. | Phone chargers, TV power supplies, car alternators. | | Light Emitting Diode (LED) | | To emit light when forward-biased. It's a diode that turns electrical energy into light energy. LEDs need a current-limiting resistor in series to prevent them from burning out. | Indicator lights on appliances (TV, decoder), traffic lights, modern light bulbs, flashlights. | | Zener Diode | | To provide a stable reference voltage. It is designed to operate in reverse bias. When the reverse voltage reaches a specific level (the Zener voltage, Vz), it "breaks down" and conducts, keeping the voltage across it constant. | Voltage regulation in power supplies to protect sensitive components from voltage fluctuations. | | Photodiode | | To detect light. It is operated in reverse bias. When light strikes it, a small current flows. The more intense the light, the more current flows. It converts light energy into electrical energy. | Automatic doors, remote controls, smoke detectors, security systems. | | Infrared (IR) Diode | (Looks like an LED) | An LED that emits infrared light, which is invisible to the human eye. It is often used in pairs with a photodiode or phototransistor. | Remote controls (the emitter), security alarm beams (like a gate sensor). | 2.3 Practical Skill: Testing a Diode