What does the Electronic and control systems topic cover?

It covers the systems approach (describing a system as input, process and output blocks with feedback), basic electronic components and Ohm's law, input subsystems including switches, the light-dependent resistor and thermistor and the voltage divider, output devices and the transistor used as a switch with a relay and protection diode, logic gates (AND, OR, NOT, NAND, NOR) with truth tables, and microcontrollers (PICs) with resistor-capacitor timing circuits. The deeper electronics is also the Unit 2 electronic and microelectronic control option.

How do you use Ohm's law to size an LED resistor?

Ohm's law is V equals I times R. To size an LED's series resistor, take the supply voltage minus the LED voltage as the voltage across the resistor, convert the LED current from milliamps to amps, then divide the voltage by the current to get the resistance. The resistor limits the current so the LED is not destroyed; choose the nearest standard resistor value.

How does a transistor work as a switch?

A small current into the transistor base turns it on, which allows a much larger current to flow through it to the output device. This lets a weak signal, for example from a sensor or logic gate, switch a larger load such as a motor or lamp. For a relay or motor, a protection (flyback) diode is fitted across the coil to absorb the high voltage produced when the inductive load switches off.

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Electronic and control systems: study guide - CCEA GCSE Technology and Design

A study guide to electronic and control systems in CCEA GCSE Technology and Design: the systems approach (input, process, output), basic components and Ohm's law, input sensors and the voltage divider, output devices and the transistor switch, logic gates with truth tables, and microcontrollers with timing circuits.

Generated by Claude Opus 4.810 min readCCEA Unit 1 and Unit 2 Option AUpdated 2026-06-14

Reviewed by: AI editorial process; not yet individually human-reviewed

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What this topic covers
How it is examined
Key ideas to recall
How to revise it

Electronic and control systems is the electronics core of Unit 1 and the basis of the Unit 2 electronic and microelectronic control option. It blends component knowledge, Ohm's law calculations, logic and programmable control.

What this topic covers

The systems approach - input, process and output blocks, feedback, and block diagrams.
Components and Ohm's law - conductors and insulators, resistors, capacitors, diodes and LEDs, and $V = IR$ .
Input sensors and subsystems - switches, the LDR and thermistor, and the voltage divider.
Output devices and the transistor switch - lamps, buzzers, motors, relays, and the transistor as a switch with a protection diode.
Logic gates and digital control - AND, OR, NOT, NAND, NOR with truth tables, and flowcharts.
Microcontrollers and timing - programmable PIC control and resistor-capacitor timing circuits.

How it is examined

Expect block diagrams, Ohm's law and LED-resistor calculations, explanations of the LDR, thermistor and voltage divider, the transistor switch and relay, logic-gate truth tables and gate selection, and questions on microcontroller advantages and RC timing. Calculations need full working for the method marks.

Key ideas to recall

A system is input -> process -> output; feedback makes it closed-loop.
Ohm's law: $V = IR$ ; an LED needs a current-limiting resistor.
A sensor changes resistance; a voltage divider turns that into a voltage.
A transistor switches a large load from a small base signal; a relay switches mains and isolates it.
AND = all inputs high; OR = any input high; NAND/NOR are the inverted versions.
A microcontroller is programmable; an RC circuit times a delay (bigger R or C = longer delay).

How to revise it

Draw block diagrams for example systems and label input, process and output.
Drill Ohm's law and the LED-resistor calculation with correct units.
Learn the sensors and the divider. Explain how resistance becomes voltage.
Master the transistor switch and relay, including the protection diode.
Learn the truth tables and practise matching a gate to a worded condition.
Know the microcontroller advantages and the RC timing relationship.

Sources & how we know this

CCEA GCSE Technology and Design specification — CCEA (2017)