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Electronic Systems: Sensors, Control, Outputs

Every electronic system is input, control and output. Meet the sensors, control devices and outputs you need to know, and learn the grade-9 habit of sorting components before you answer.

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What you'll cover

Input, process, output 🔌

Every electronic system, from a burglar alarm to a games controller, follows the same simple pattern: an **input** senses the world, a **control** part decides what to do, and an **output** makes something happen. This module covers the three parts of an electronic system, the **sensors**, **control devices** and **outputs** you need to know, and the grade-9 habit of **sorting** components before you answer.

The words you need 🔑

Five ideas run through electronic systems:

What does a sensor do? 📡

In an electronic system, what is the job of an input sensor?

  • It detects a change in the surroundings, such as light or temperature
  • It produces a sound or light to alert the user
  • It decides what the whole system should do
  • It supplies power to the rest of the circuit

The systems model 🧭

Every electronic system has **three stages**: **Input**: a sensor detects a change, an LDR for light or a thermistor for heat. **Control**: a device processes the signal, such as a switch, transistor or resistor. **Output**: a device produces a result, such as a buzzer for sound or an LED for light. Trace any circuit as **input, then control, then output**.

Match each component to its job 🧩

  • LDR
  • Thermistor
  • Buzzer
  • LED
  • Detects the level of light
  • Detects temperature
  • Produces a sound
  • Produces light as an output

Trace the signal 🪜

An interactive activity.

Which are input sensors? ✅

Select the TWO components that are input sensors.

  • A light-dependent resistor
  • A thermistor
  • A buzzer
  • An LED

Inputs versus outputs ⚖️

Two kinds of device sit at opposite ends of a system.

Complete the system 🧱

Every electronic system has three stages. An _____ sensor detects a change; for example an _____ detects light and a _____ detects temperature. A control device such as a _____ then switches the circuit, and finally an _____ device such as a buzzer or LED produces the result.

input LDR thermistor transistor output resistor motor battery capacitor diode

What does a transistor do? 🎚️

In the control part of a circuit, what does a transistor mainly do?

  • It acts as an electronic switch, turning the output on or off
  • It detects light and temperature changes
  • It produces the sound in a buzzer
  • It stores charge like a battery

Find the inputs 🖍️

An interactive activity.

Sort the system 🔀

An interactive activity.

Design a system ✍️

An interactive activity.

The grade-9 habit 🏆

Top answers **sort the components first**. Before you write, label each one as **input**, **control** or **output**: a sensor like an **LDR** or **thermistor** is an input; a **transistor** or **resistor** is control; a **buzzer** or **LED** is an output. Then describe the system in that order, **input to control to output**, and say what each part does. Sort first, then trace the signal - top band.