Input and Output Devices: Examples and Definitions

High school Design & Technology students are often asked to understand and identify and name different features of control systems, such as input devices, processing elements, output devices, and feedback. This article summarises this content and helps students prepare for examination questions on this topic.

What is ‘systems thinking’?

• A simple way of thinking about complex systems
• Common in electronic and mechanical systems – including systems that integrate mechanical, electronic, and computer components
• Categorises components of the system into separate blocks: input, processing, output and feedback
• Does not require complex terminology or specialist knowledge to understand the system, making it easy to describe to those with non-technical backgrounds (i.e. clients)
• Makes easer to troubleshoot errors

What is ‘feedback’ in system analysis and design?

• Feedback is the mechanism whereby output influences future behavior of the system
• Example: a thermostat might measure the temperature in the room, so it then knows whether to increase or decrease the temperature.
• The output is measured in some way and becomes a input to adjust the future behavior of the system
• Feedback creates a loop in the system, allowing self-regulation and control
• helping to minimise errors in the system, ensuring the system adapts to change and operates efficiently within its environment.
• Feedback can be positive (amplifying certain behaviors or outputs) or negative (triggering corrective actions or reducing certain outputs)

In the context of system analysis and feedback systems, amplification refers to increasing the strength or magnitude of a signal – typically the output signal – based on input or feedback. For example, in a temperature control system, a sensor might produce a small voltage as input; the microcontroller processes this, and an amplifier may boost the signal to activate a heater with enough power.

Examples of input, process, and output devices

Input devices

• Turn light, sound, movement or other real-world inputs into an electronic signal
• Examples:
  • Digital cameras (converts light into a digital file)
  • Mouse and keyboard (convert movement / pushing buttons into a digital signal)
  • Graphics tablet (converts pressure on surface into a digital signal)
  • Scanner

Process devices / components

• Changes/modifies electronic signals within the system
• Processing Software:
  • Techsoft Design
  • Adobe Illustrator

Output devices

• Turns electronic signals back into real-world signals, such as light, heat, sound
• Examples:
  • Digital Printers
  • Laser cutters
  • 3D printers

These control levels reflect how much autonomy the system has and how heavily it relies on human input to function.

Manual, semi-automatic and automatic control

• Manual control – a human operator reading inputs (like gauges or sensors) and deciding what actions to take.
• Semi-automatic control – combines human and machine input. For example, the system might gather and display feedback data (e.g., a digital thermometer), but the human still decides and initiates the response, like pressing a button to turn on a fan.
• Automatic control – the system handles everything on its own. A microcontroller continuously reads inputs, processes the data, and adjusts outputs (like temperature or motor speed) without any human intervention. It forms a closed-loop system, adjusting itself in real time based on feedback.

Digital control systems often use microcontrollers – small computers on a single chip, which has a processor (the brain), memory, and input/output (I/O) ports, all packed into one tiny unit. Microcontrollers can perform specific control tasks in electronic systems like reading a sensor, processing that input, and then sending a feedback signal to make something happen (like turning on a fan, adjusting a motor, or changing a light). They are used when automatic, real-time decision-making is needed based on sensor output.

Why designers use basic control principles of input, process, output, feedback and amplification

• A concise way of thinking about complicated systems: Thinking in terms of control systems allows designers to consider all aspects of a system and how they related.  This helps people understand the purpose of each part of the system.
• Testing of design ideas: Designers use control principles to validate their ideas before full production begins. For example, when designing interactive point-of-sale displays, they test how user input (touching a screen) creates the desired output (information display), ensuring the concept functions as intended.
• User experience optimisation: Understanding the relationship between input and output helps designers create more intuitive products. This also helps assess how different components work together, ensuring various sensors (inputs) work harmoniously with display elements (outputs) to create a coherent user experience. In interactive displays, visual, auditory, or tactile feedback (output) might confirm successful user actions (input), improving the user experience. In digital signage systems, designers can test how user interactions (input) lead to content changes (output), ensuring the response time and behaviour meet user expectations.
• Cost savings: By monitoring control systems, designers can identify the most efficient ways to achieve desired results. For instance, in smart packaging design, understanding how much sensor technology (input) is needed to achieve the required interactivity (output) helps optimize production costs.
• Quality control: Monitoring input and output helps maintain consistent product performance. For example, a factory creating packaging might use automated sensors (input) to monitor product alignment while feedback systems adjust positioning mechanisms (output) to ensure precise and reliable cutting of nets. Feedback allows designers to develop ‘responsive’ machines, which allow continuous monitoring of performance. In digital print production, constant monitoring of print quality (input) enables automatic adjustments (output) to maintain consistent results and helping to prevent errors, minimising waste. Amplification refers to how a system adjusts its response based on feedback to achieve the desired outcome. For example, in an automated printing system, if feedback indicates that print colours are too faint, the system amplifies the ink flow or pressure (adjusts the response) until the desired colour intensity is achieved (output). This continuous monitoring and adjustment process ensures the system maintains optimal performance. Amplification can also improve safety, with parts of the system set to switch off if certain limits are reached.
• Maintenance planning: Understanding control systems helps designers plan for product maintenance. For instance, monitoring systems in digital displays can provide feedback about component wear, enabling predictive maintenance schedules.
• Environmental adaptation: Control principles allow products to adapt to changing conditions. Smart packaging might use environmental sensors (input) to adjust protective properties (output) based on temperature or humidity changes. Understanding control principles helps designers optimize resource use. In automated packaging systems, feedback loops ensure minimal material waste while maintaining quality standards.