What does the WJEC A-level Electronics non-exam assessment require, and how is it marked?
Extended System Design and Realisation Task (non-exam assessment): designing, building, testing and evaluating a working electronic system to a brief, and how it is assessed.
A concise overview of the WJEC A-Level Electronics non-exam assessment, the Extended System Design and Realisation Task, covering what it asks (design, build, test and evaluate a working system to a brief), the stages, how it is assessed and weighted, and how to approach it.
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What this dot point is asking
Component 3 is the non-exam assessment (NEA) of WJEC Eduqas A-level Electronics: the Extended System Design and Realisation Task. Rather than a written paper, it asks you to design, build, test and evaluate a complete working electronic system in response to a brief, drawing on the core concepts and the sub-systems studied across Components 1 and 2. This single overview sets out what the task involves and how it is assessed; the engineering knowledge itself lives in the other modules.
The answer
What the task is
The stages
How it draws on the rest of the course
The design task is synoptic in spirit: a typical system combines an input sub-system (a sensor in a potential divider), processing (a comparator, logic, a 555 timer or a microcontroller), and an output sub-system (a transistor-driven load), exactly the building blocks studied elsewhere. The engineering detail is in those modules; the task assesses your ability to combine and apply them.
Examples in context
- Example 1. A measurement instrument
- A brief for a digital thermometer leads to an instrumentation chain: a sensor bridge, signal conditioning with an instrumentation amplifier, an ADC read by a microcontroller, and a display. The task rewards justifying each stage and testing the calibrated reading against known temperatures.
- Example 2. A timed control system
- A brief for a stairwell light controller leads to a 555 monostable (or microcontroller delay) triggered by a switch, driving a relay. The design must justify the timing components against the required on-time, and testing must measure the actual delay against the specification.
- Example 3. A communications or audio project
- A brief for a small intercom or audio mixer leads to a chain of amplifiers, a summing mixer and a power output stage. The task assesses how well the sub-systems are combined, built and tested, and how honestly the finished system is evaluated against the brief.
Try this
Q1. State the five main stages of the Extended System Design and Realisation Task. [3 marks]
- Cue. Specification (from the brief), design (justified systems approach), realisation (build), testing (against the specification), and evaluation (evidence-based, against the brief).
Q2. Explain why the design should follow a systems (block-diagram) approach rather than going straight to a circuit. [2 marks]
- Cue. A block diagram lets each sub-system be specified and justified against the brief and tested by function; it earns the systems-design marks and makes fault-finding and evaluation easier than an unstructured circuit.
Exam-style practice questions
Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
WJEC Eduqas (assessment guidance)20 marksHow should the design stage of the Extended System Design and Realisation Task be approached to gain the most marks?Show worked answer →
The design stage is assessed on how well the system is planned from the brief, so it must be thorough and justified.
Start by analysing the brief into a clear specification: list exactly what the system must do, its inputs, outputs and constraints. Then take a systems approach: draw a block diagram of input, processing and output sub-systems, and justify the choice of each block (for example, a comparator for a threshold, a 555 astable for timing, a transistor driver for a high-current output).
Develop each block into a circuit, showing calculations (resistor values, gains, timing) that justify the component choices against the specification, and consider alternatives. A strong design is one where every decision is traced back to a requirement in the brief.
Markers reward a clear specification from the brief, a justified systems-level design, and calculations that link component choices to the requirements.
WJEC Eduqas (assessment guidance)20 marksWhat is expected in the testing and evaluation stages of the system design task?Show worked answer →
Testing must show that the built system meets the specification. Plan tests for each function (for example, measure the switching threshold, the timing period, the output drive), record the results, and compare them against the specification, using appropriate test equipment such as a multimeter and oscilloscope.
Where the system does not behave as intended, fault-finding should be documented: identify the symptom, reason about which sub-system is responsible (checking the signal at each interface), and record the fix.
Evaluation then judges the finished system against the original brief: state what works, what does not, the limitations, and realistic improvements, supported by the test evidence rather than opinion.
Markers reward a structured test plan with recorded results compared to the specification, documented fault-finding, and an evidence-based evaluation against the brief.
Related dot points
- System synthesis: the systems approach, block diagrams, building a system from input, process and output sub-systems, and interfacing between blocks.
A focused answer to the WJEC A-Level Electronics core concept of system synthesis, covering the systems approach, three-block input-process-output diagrams, signal flow, interfacing between sub-systems, and how complex products are built up from standard building blocks.
- Microcontroller programming: flowcharts, sequence, selection and iteration, input and output instructions, time delays, subroutines, and translating a system specification into a program.
A focused answer to WJEC A-Level Electronics microcontroller programming, covering flowcharts, the program structures of sequence, selection and iteration, input and output instructions, time delays, subroutines, and turning a system specification into a working program.
- Operational amplifier properties and the comparator: the ideal op-amp, open-loop gain, the comparator with and without hysteresis, and the Schmitt trigger.
A focused answer to WJEC A-Level Electronics operational amplifier properties and the comparator, covering the ideal op-amp model, open-loop gain, the inverting and non-inverting comparator, hysteresis, and the Schmitt trigger.
- Timing circuits and oscillators: RC timing, the monostable and astable using the 555 timer or op-amp, the period and frequency equations, and the production of square waves and clock signals.
A focused answer to WJEC A-Level Electronics timing circuits and oscillators, covering RC timing, the monostable (one-shot) and astable multivibrator using the 555 timer or an op-amp, the period and frequency equations, and the generation of square waves and clock signals.
- Instrumentation systems: sensors and transducers, the Wheatstone bridge, signal conditioning and amplification, calibration, and the use of the instrumentation amplifier.
A focused answer to WJEC A-Level Electronics instrumentation systems, covering sensors and transducers, the Wheatstone bridge for resistive sensors, signal conditioning and amplification, calibration, and the role of the instrumentation amplifier.
Sources & how we know this
- WJEC Eduqas GCE A-level Electronics specification — WJEC Eduqas (2017)