Inputs (AQA GCSE Design & Technology): Revision Note

The use of light sensors

What is a light sensor?

• A light sensor is an example of an input to an electronic circuit which detects levels of light

• The sensing component is called an LDR (Light Dependent Resistor)

• Different levels of light change the resistance of the component, which in turn changes how electrical current passes through it

• While LDRs can directly influence circuit components, microcontrollers are needed for complex applications

Example uses of light sensors

• Automatic street lighting that activates during low-light conditions

• Motorised window blinds responding to sunlight levels

• Security systems detecting light changes at entry points

The use of temperature sensors

What is a temperature sensor?

• A temperature sensor is an example of an input to an electronic circuit which detects different levels of heat

• The sensing component is known as a thermistor

• Different levels of temperature change the resistance of the component, which in turn changes how electrical current passes through it

• Similar to light sensors, thermistors can affect circuits directly, but processors enable more sophisticated applications

Example uses of temperature sensors

• Home central heating thermostats

• Electric kettles (turning off at target temperature)

• Laptop cooling fans (temperature-responsive activation)

The use of pressure sensors

What is a pressure sensor?

• A pressure sensor is an example of an input to an electronic circuit which detects different levels of force

• Sensing components include pressure switches and FSRs (Force Sensitive Resistors)

• Different levels of pressure change the resistance of the component, which in turn changes how electrical current passes through it

• Processors are required for more complex applications

Example uses of pressure sensors

• Automatic sliding doors (pressure activation)

• Touch-sensitive lighting (pressure controls brightness)

• Digital scales (weight-responsive display)

The use of switches

What is a switch?

• A switch is an input component which controls the flow of electricity in a circuit (on/off)

• Switches are manually operated by users

• Types of switch include: push-to-make, push-to-break and toggle switch