Homeschool Guide: These lesson plans are a guide for parents. Content may contain errors — always cross-reference with official exam board specifications.

power supplies & regulation

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4 detailed 50-minute lessons with teaching scripts, worked examples, parent guides, and assessment criteria.

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Lesson Overview

Total Lessons: 4
Tier: Foundation and Higher
Duration: 50 minutes per lesson (200 minutes total)
Exam Boards: AQA, Edexcel, OCR, Eduqas, CCEA

Learning Objectives

Prerequisites

Materials & Equipment

Lesson 1: Introduction: power supplies & regulation

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Write down everything you already know about power supplies & regulation. Then check against the key terms: key terms from power supplies & regulation. Use a mini-whiteboard or paper.

Main Content (35 minutes)

Parent/Teacher Guide:
Before lesson: Read the script below. Pre-teach key vocab: key terms from power supplies & regulation.
If stuck: Re-read the revision notes (link above), then break the content into smaller steps.
Extension: See the Stretch & Challenge ideas in Lesson 4.
Teaching Script (35 mins):
Mins 0-5 - Hook: "Today: power supplies & regulation. By the end you will be able to answer exam questions on it unaided. It connects to the rest of Electronics because the ideas here recur across the spec."
Mins 5-20 - Direct Instruction: Work through the core ideas below one at a time; after each, ask your student to explain it back in their own words.
Mins 20-30 - Guided Practice: Model the worked example together, then let your student attempt the first practice question with guidance.
Mins 30-35 - Independent Practice: 2-3 practice questions from Lesson 3 below, with immediate feedback.
First Look

Start with the revision notes summary, then attempt: explain the key ideas of power supplies & regulation

Plenary (5 minutes)

Check Out

Your student states one thing they learned and one question they still have about power supplies & regulation.

Lesson 2: Core Concepts: power supplies & regulation

Duration: 50 minutes

Starter Activity (5 minutes)

Review Previous Lesson

Quick recap: write 3 key points from Lesson 1 on power supplies & regulation. Check them against the notes below.

Main Content (35 minutes)

Key Fact: A power supply converts AC mains to a stable DC voltage through transformer, rectifier, smoothing and regulation stages.
Key Fact: A step-down transformer reduces the AC mains voltage to a lower AC voltage suitable for the circuit.
Key Fact: Half-wave rectification uses a single diode and only rectifies one half of the AC cycle, giving 50% efficiency.
Key Fact: Full-wave rectification using a bridge rectifier uses four diodes and rectifies both halves of the AC cycle.
Key Fact: The output of a rectifier is pulsating DC; a smoothing capacitor converts this to a more constant DC level.
Key Fact: Ripple voltage is the residual AC variation on the DC output; larger capacitance reduces ripple for a given load current.

Practice (10 minutes)

Q: explain the key ideas of power supplies & regulation

Answer:

Plenary (5 minutes)

Explain Back

Your student teaches the key points back to you without looking. Fill any gaps immediately.

Lesson 3: Application: power supplies & regulation

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Recall the key terms: key terms from power supplies & regulation. Define each in one sentence.

Main Content (35 minutes)

Parent/Teacher Guide: Let your student attempt each question alone first, then compare with the model answer. Award method marks for correct working even if the final answer is wrong.

Work through the practice questions on the revision notes page for this topic.

Plenary (5 minutes)

Error Review

Review any questions answered incorrectly. Identify whether the error was knowledge, method, or reading the question.

Lesson 4: Exam Practice: power supplies & regulation

Duration: 50 minutes

Starter Activity (5 minutes)

Command Words

Review what these command words require: state (one point), describe (say what happens), explain (say why), compare (both sides), evaluate (judgement).

Main Content (35 minutes)

Extended Answer

Extended question: Full-Mark Response Describe the stages of a regulated DC power supply from mains AC input to stable DC output, explaining the role of rectification, smoothing and voltage regulation. <div class="

A regulated DC power supply converts mains AC to stable DC through four stages. First, a step-down transformer reduces the 230 V AC mains to a lower AC voltage (e.g. 12 V AC). Second, a rectifier converts the AC to pulsating DC: a half-wave rectifier uses one diode and only passes one half-cycle, while a bridge rectifier uses four diodes to pass both half-cycles, producing full-wave rectified DC with a ripple frequency of 100 Hz. Third, a smoothing capacitor (typically hundreds or thousands of microfarads) charges during the rectifier peaks and discharges into the load during the troughs, reducing the ripple voltage. The ripple is approximately V_ripple = I_load/(f × C). Fourth, a voltage regulator provides a constant output voltage regardless of remaining ripple or load current changes. A Zener diode regulator uses the reverse breakdown voltage as a reference, with a series resistor to limit current. A three-terminal IC regulator (e.g. 7805) provides tighter regulation with built-in current limiting and thermal shutdown. The result is a clean, stable DC supply suitable for powering electronic circuits.

Exam Tips: Draw the full power supply block diagram: transformer → rectifier → smoothing → regulator, and label each stage. | For ripple calculations, always identify whether it is half-wave (f = 50 Hz) or full-wave (f = 100 Hz) before using V_ripple ≈ I/(fC). | When calculating Zener series resistance, include both the Zener current and the load current in the denominator. | State the purpose of each stage before attempting calculations: transformer (voltage reduction), rectifier (AC to DC), smoothing (reduce ripple), regulator (constant voltage). | Remember that a Zener diode regulator requires a minimum Zener current to maintain regulation; check this condition in your answer.
Common Errors: ✗ Using 50 Hz for the ripple frequency of a full-wave rectifier. ✓ Full-wave rectification doubles the frequency; the ripple frequency is 100 Hz on a 50 Hz mains supply. ✗ Forgetting to include load current when calculating the Zener series resistor. ✓ R_s = (V_in − V_Z)/(I_Z + I_load); both Zener and load current flow through the series resistor. ✗ Assuming a smoothing capacitor removes all ripple. ✓ A capacitor reduces ripple but does not eliminate it; some AC variation always remains on the DC output. ✗ Confusing linear and switch-mode regulator efficiency. ✓ Linear regulators dissipate excess voltage as heat (low efficiency with large V_drop); SMPS achieve higher efficiency by switching
Stretch & Challenge (Grade 8-9):
  • Synoptic links: explain how power supplies &amp; regulation connects to another Electronics topic you have studied
  • Real-world: research one real-world use or example of power supplies &amp; regulation
  • Critical: "What are the limitations of the models used in power supplies &amp; regulation?"

Plenary (5 minutes)

Assessment Criteria
  • Got it: Confident explanation + correct worked examples
  • Getting there: Main points OK, needs support with detail
  • Not yet: Confused on key concepts - re-run Lesson 2

Homework & Consolidation

Recommended Resources

🎓 Smart Lesson (Guided)