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VCE Systems Engineering (Year 11) · Unit 1 — Electrotechnological Systems Design · 11m read

Systems Thinking — Electrotechnological Systems and Society

Systems Engineering starts with a way of thinking: every system takes inputs, processes them and produces outputs — and the best systems check their own results.

Learning objective: Describe systems using input–process–output models, distinguish open-loop and closed-loop control, and discuss the impacts of electrotechnological systems on society.

By the end of this lesson you can:

  • I can draw a block diagram of a system with feedback.
  • I can distinguish open-loop and closed-loop systems.
  • I can discuss positive and negative impacts of a technology.

A thermostat versus a timer. A heater on a timer runs for an hour no matter how warm the room gets (open loop). A heater with a thermostat measures the room and switches off when it is warm enough (closed loop).

System models

INPUT → PROCESS → OUTPUT
• Input: energy or signals entering the system (switch, sensor, battery).
• Process: what changes them (microcontroller, circuit, gears).
• Output: the result (light, motion, sound, heat).

FEEDBACK — information about the output returned to the input.
• OPEN-LOOP control: no feedback (e.g. a toaster on a timer).
• CLOSED-LOOP control: uses feedback to adjust (e.g. cruise control, thermostat).

SUBSYSTEMS — complex systems are broken into smaller systems (power supply, control, output).

SOCIETY — electrotechnological systems affect jobs, health, privacy, energy use, e-waste and access. Engineers weigh benefits against impacts.

Worked example (Easy)

Describe an automatic night light as an input–process–output system and say whether it is open or closed loop.

  1. Input. Light-dependent resistor (LDR) senses light level.
  2. Process. Circuit or microcontroller compares the level with a threshold.
  3. Output. LED switches on when it is dark.
  4. Control. It responds to a sensed condition but does not measure its own output → usually described as open loop.

Answer: LDR input → comparison process → LED output; it reacts to ambient light but has no feedback from the LED, so it is open loop.

Common mistakes

  • Calling any system with a sensor "closed loop" Closed loop requires feedback about the OUTPUT. Fix: Ask: does the system measure its own result and adjust?
  • Only listing benefits of a technology Impacts include negatives such as e-waste and energy use. Fix: Discuss both and weigh them.

Practice questions

  1. Which is a closed-loop system?

    1. A toaster on a timer
    2. A sprinkler on a fixed schedule
    3. A thermostat-controlled heater
    4. A torch with a switch

    (1 marks)

  2. Discuss one positive and one negative impact of smart home devices on society.

    (3 marks)

Summary

  • Input → process → output.
  • Open loop: no feedback; closed loop: feedback adjusts output.
  • Break complex systems into subsystems.
  • Weigh social and environmental impacts.

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