Systems Approach to Designing
Systems Approach to Designing
Many products use electronic systems to provide functionality. A security light that switches on when someone approaches, a washing machine that controls water temperature, or a music speaker that amplifies sound — all use a systems approach. Understanding how electronic systems work helps you design products that respond to their environment.
The Input–Process–Output Model
Every electronic system follows the same basic structure: input → process → output. The input component detects a change in the environment (light, temperature, pressure). The process component makes a decision about what to do with that information. The output component performs an action (sound, light, movement).
All electronic systems follow the input → process → output model. Inputs detect changes in the environment; the process makes decisions; outputs perform actions.
Input Devices
Input devices (also called sensors) detect changes and convert them into electrical signals that the system can process.
Light sensors (LDRs) detect light levels. Their resistance changes depending on brightness. Used in automatic streetlights that switch on when it gets dark.
Temperature sensors (thermistors) detect temperature changes. Their resistance decreases as temperature rises. Used in central heating thermostats and car engine monitors.
Pressure sensors detect physical force. Used in car seat sensors (to trigger seatbelt warnings) and digital scales.
Switches are the simplest input devices. They include push switches (doorbells), toggle switches (light switches), tilt switches (detecting orientation) and reed switches (activated by magnets, used in security alarms).
Process: Microcontrollers
The process stage is handled by a microcontroller — a small, programmable computer on a single chip. Microcontrollers can be programmed to act as:
Counters — counting the number of times an event occurs (e.g. counting items on a production line). Timers — triggering actions after a set time (e.g. turning off a light after 30 seconds). Decision makers — using logic to choose between actions based on sensor data (e.g. if temperature is above 25°C, switch on the fan).
Microcontrollers can be programmed as counters (counting events), timers (triggering actions after a set time) and decision makers (choosing actions based on sensor data). They are the “brain” of an electronic system.
Output Devices
Output devices perform the action that the system is designed to produce.
Buzzers produce a simple tone and are used in alarms, timers and doorbells. Speakers produce a wider range of sounds and are used in phones, radios and music systems. Lamps/LEDs produce light and are used for indicators, displays and illumination. Motors produce rotary movement and are used in fans, conveyor belts and electric vehicles.
When designing an electronic system, you need to match the right input, process and output components. For example, a security light system uses a motion sensor (input) connected to a microcontroller (process) that switches on a lamp (output) when movement is detected, then uses a timer to switch it off after a set period.