Lesson Note on Transistors: Types of Transistors, Meaning and Symbols for SS 2

Class: Senior Secondary School 2 (SS2 / SSS2)
Term: 1st Term
Week: 10
Age: 16 years
Duration: 45 minutes
Subject: Basic Electronics
Curriculum Theme: Basic Electronics
Previous Lesson: Transistors: Concept of Transistors and Biasing of Transistors.
Topic: TRANSISTORS
Subject Matter: Meaning of TRANSISTORS (recap definition of transistor), types of transistors bipolar transistor (NPN and PNP), field effect transistor FET (N-channel and P-channel), MOSFET transistors (meaning and symbols).

Specific Objectives

By the end of the lesson, pupils should be able to:

Cognitive Domain:

• Define a transistor and explain its function.
• Identify and differentiate between the main types of transistors.
• Describe the characteristics of NPN and PNP bipolar transistors.

Affective Domain:

• Appreciate the importance of transistors as fundamental electronic components.
• Show interest in learning more about transistor applications in circuits.

Psychomotor Domain:

• Draw the circuit symbols for NPN, PNP, N-channel FET, P-channel FET, and MOSFET transistors.
• Identify the terminals of different transistor types.

Social Domain:

• Work collaboratively to discuss and identify different transistor types and their symbols.

Reference Materials

The following resources were used in planning this lesson:

• Senior Secondary Schools Education Curriculum
• State Unified Scheme of Work
• Theraja, B. L. (2010). Basic Electronics. S. Chand & Company Ltd.
• https://www.electronics-tutorials.ws/transistor/transistor_1.html
• https://www.allaboutcircuits.com/textbook/semiconductors/chpt-4/bipolar-junction-transistors/

Instructional Materials

The teacher will teach this lesson with the aid of:

• Chart showing types of transistors, biasing arrangements, and bipolar transistor circuits.
• Whiteboard and markers.
• Circuit diagrams of common emitter, collector, and base configurations.

Rationale for the Lesson

This lesson helps pupils understand transistors as essential components in modern electronics, enabling them to grasp how electronic devices amplify signals and switch currents. It provides foundational knowledge for further studies in electronics and technology.

Prerequisite/Previous Knowledge

Pupils have basic knowledge of semiconductor devices like diodes and fundamental electrical concepts such as voltage and current.

Lesson Content/Board Summary

TRANSISTORS

Meaning of Transistors

A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is one of the fundamental building blocks of modern electronic devices like radios, computers, and mobile phones.

Types of Transistors

Transistors are broadly classified into two main types:

• Bipolar Junction Transistors (BJTs)
• Field-Effect Transistors (FETs)

Bipolar Junction Transistors (BJTs)

BJTs are current-controlled devices. They have three terminals: Base (B), Collector (C), and Emitter (E).

There are two types of BJTs:

• NPN Transistor: Consists of a p-type semiconductor sandwiched between two n-type semiconductors. Its symbol has an arrow pointing out from the Emitter terminal.
• PNP Transistor: Consists of an n-type semiconductor sandwiched between two p-type semiconductors. Its symbol has an arrow pointing in towards the Emitter terminal.

Symbols for BJTs

The NPN transistor symbol shows the emitter arrow pointing outwards, while the PNP transistor symbol shows the emitter arrow pointing inwards.

(Teacher will draw and label the NPN and PNP symbols on the board.)

Field-Effect Transistors (FETs)

FETs are voltage-controlled devices. They have three terminals: Gate (G), Drain (D), and Source (S).

There are two main types of FETs:

• Junction Field-Effect Transistor (JFET): Controls current flow through a channel by varying the voltage across a reverse-biased p-n junction (gate).
• Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET): Controls current flow through a channel by varying the voltage on an insulated gate. MOSFETs have very high input impedance.

Types of JFETs

• N-channel JFET
• P-channel JFET

Types of MOSFETs

• Depletion-type MOSFET (D-MOSFET)
• Enhancement-type MOSFET (E-MOSFET)

Symbols for FETs and MOSFETs

Each type (N-channel JFET, P-channel JFET, N-channel D-MOSFET, P-channel D-MOSFET, N-channel E-MOSFET, P-channel E-MOSFET) has a distinct circuit symbol, indicating the channel type and gate structure.

(Teacher will draw and label relevant FET and MOSFET symbols on the board.)

Basic Bipolar Transistor Circuits

BJTs can be configured in different ways to achieve specific circuit characteristics:

• Common Emitter (CE) Configuration: Used primarily for voltage amplification. The input signal is applied between the base and emitter, and the output is taken between the collector and emitter.
• Common Collector (CC) Configuration (Emitter Follower): Used for current amplification and impedance matching. The input is applied between the base and collector, and the output is taken between the emitter and collector.
• Common Base (CB) Configuration: Used for high-frequency applications and impedance matching. The input is applied between the emitter and base, and the output is taken between the collector and base.

Teaching Methods/Instructional Techniques

Discussion, Lecture, Demonstration, Question and Answer, Visual Aids

Instructional Procedures

Step 1: Introduction

Time: 5 minutes

Teaching Skill: Set Induction

Teacher’s Activity: The teacher greets the pupils and asks them to recall previous knowledge on semiconductor materials and diodes. The teacher then introduces the topic “TRANSISTORS” by explaining their importance in modern electronics.

Pupils’ Activity: Pupils respond to the teacher’s questions and listen attentively to the introduction of the new topic.

Learning Point: Pupils are reminded of previous knowledge and introduced to the topic.

Step 2: Meaning of Transistors

Time: 7 minutes

Teaching Skill: Explanation/Definition

Teacher’s Activity: The teacher defines a transistor as a semiconductor device for amplifying or switching electronic signals and power, highlighting its role as a building block for electronics.

Pupils’ Activity: Pupils listen, take notes, and ask questions for clarification.

Learning Point: Pupils understand the fundamental definition and function of a transistor.

Step 3: Types of Transistors

Time: 8 minutes

Teaching Skill: Classification/Categorization

Teacher’s Activity: The teacher explains the two main types of transistors: Bipolar Junction Transistors (BJTs) and Field-Effect Transistors (FETs), and briefly mentions MOSFETs as a sub-type of FET.

Pupils’ Activity: Pupils listen, observe the chart, and note down the classifications.

Learning Point: Pupils identify the broad categories of transistors.

Step 4: Bipolar Junction Transistors (BJTs)

Time: 7 minutes

Teaching Skill: Explanation/Demonstration

Teacher’s Activity: The teacher explains NPN and PNP BJTs, their terminal names (Base, Collector, Emitter), and draws their respective circuit symbols on the board, emphasizing the arrow direction for the emitter.

Pupils’ Activity: Pupils observe the symbols, copy them into their notebooks, and identify the terminals.

Learning Point: Pupils understand NPN and PNP transistors and can draw their symbols.

Step 5: Field-Effect Transistors (FETs) and MOSFETs

Time: 6 minutes

Teaching Skill: Explanation/Comparison

Teacher’s Activity: The teacher explains FETs (JFETs and MOSFETs), their terminal names (Gate, Drain, Source), and draws their symbols, differentiating between N-channel and P-channel types, and D-MOSFETs/E-MOSFETs.

Pupils’ Activity: Pupils pay attention, copy the symbols, and note the differences between FET types.

Learning Point: Pupils understand FETs and MOSFETs and can draw their symbols.

Step 6: Basic Bipolar Transistor Circuits

Time: 7 minutes

Teaching Skill: Discussion/Illustration

Teacher’s Activity: The teacher discusses the three basic BJT circuit configurations: Common Emitter, Common Collector, and Common Base, highlighting their primary uses and showing simple diagrams on the chart.

Pupils’ Activity: Pupils observe the circuit diagrams, listen to the explanations, and ask questions about their applications.

Learning Point: Pupils understand the different ways transistors can be connected in circuits.

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

1. What is a transistor?
2. Mention the two main types of transistors.
3. Differentiate between an NPN and a PNP transistor.
4. Draw the circuit symbol for an N-channel JFET and an NPN transistor.

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Pupils demonstrate understanding of the lesson.

Step 8: Conclusion

Time: 5 minutes

Teaching Skill: Summarization/Assignment

Teacher’s Activity: The teacher summarizes the key learning points about transistors, their types, and symbols. The teacher then assigns homework for pupils to research practical applications of transistors in everyday devices.

Pupils’ Activity: Pupils listen to the summary and copy the homework assignment.

Learning Point: Pupils consolidate their understanding and are encouraged to explore further.

Lesson Keywords

• Transistor – A semiconductor device used to amplify or switch electronic signals.
• BJT – Bipolar Junction Transistor.
• NPN – A type of BJT with an N-type emitter, P-type base, and N-type collector.
• PNP – A type of BJT with a P-type emitter, N-type base, and P-type collector.
• FET – Field-Effect Transistor.
• MOSFET – Metal-Oxide-Semiconductor Field-Effect Transistor.
• Common Emitter – A BJT configuration used for voltage amplification.
• Common Collector – A BJT configuration used for current amplification and impedance matching.
• Common Base – A BJT configuration used for high-frequency applications.

Differentiation

For pupils who grasp concepts quickly, the teacher can provide additional challenges such as identifying transistor terminals on actual components or discussing specific applications. For pupils needing more support, the teacher will provide simplified diagrams and offer one-on-one guidance during drawing exercises.

Note for teachers using this lesson plan

Ensure the chart on transistors is clearly visible and well-labeled. Encourage pupils to actively participate in drawing and identifying symbols. Emphasize the practical significance of transistors in modern technology to keep pupils engaged. Provide sufficient time for pupils to copy diagrams accurately.