Electronic Circuits

Design and build functional electronic circuits

Designing Functional Circuits

In Grade 9, you design and build electronic circuits that solve real problems. This involves selecting appropriate components, calculating values (like resistor size), drawing circuit diagrams, building on breadboards and testing. Your circuit must be safe, functional and well-documented.

Example

Design a Light-Sensitive Circuit

Problem: Automatic night light (turns on when dark) Components: • LDR (Light Dependent Resistor): resistance changes with light • Transistor: acts as switch • LED: the light output • Resistors: protect components • Battery: power supply How it works: In darkness → LDR resistance high → transistor switches on → LED lights up Build on breadboard first, test, then solder permanently

Note

Remember

Always draw the circuit diagram BEFORE building. Calculate resistor values using Ohm's law (V = I × R). Test circuits at low voltage first. Document your design process. Electronic circuits are in almost every modern device — understanding them opens many career paths in SA's growing tech sector.

Key Vocabulary

LDRLight Dependent Resistor — resistance changes with light level

BreadboardA board for building temporary circuits without soldering

Ohm's lawV = I × R (voltage = current × resistance)

SensorA device that detects changes in the environment

SASL Avatar

Loading avatar...

1 / 4

LDR

Speed: