Systems and Circuits

Systems are made up of several parts that work together to execute a function.

All electronic systems require an input, process, and output.

Circuits are a sequence of components connected by wires to a source of power.

Circuit diagrams, made up of lines and symbols, are used to show how they work.

Printed Circuit Boards support and connect electronic components. They are non-conductive boards specially designed for a circuit, which have components mounted directly onto them.

Input Devices

Switches

• Switches complete or disconnect a circuit by being closed or opened respectively.

• They come in many forms, like toggles, slides, pushes, and microswitches.

Light-Dependent Resistors

• LDRs detect changes in light levels

• Resistance increases in the dark, limiting the current, and decreases in the light, allow the current to flow.

• They are often used in items like street lights.

Thermistors

• Thermistors detect changes in temperature.

• Resistance decreases when it is warm, and increases when it is cold.

• They are often used in air conditioning.

Pressure Sensors

• Pressure sensors detect changes in pressure.

• Resistance can increase or decrease when pressure increases depending on the sensor

• They are often used in car tires

Process Devices

Process devices process the information from the input device to decide and appropriate output.

Most processes in electronic systems are carried out by integrated circuits, which are capable of performing multiple tasks.

Microcontrollers.

A microcontroller is a type of integrated circuit which is programmed to perform certain task in a variety of devices. It contains memory, input, output and processor, making it essentially a miniature computer.

They can be adapted to do a variety of tasks using programs, which are then stored in the microcontroller’s memory. These programs are written using or programming languages, or a converted flowchart.

Microcontrollers are often used as timers or counters.

Decision Making

Circuits can be programmed to make decisions, often using logic gates.

There are three types of logic gate: NOT, AND, and OR.

A NOT gate takes an input and outputs the opposite value.

An AND gate take at least two inputs and, if all inputs are 1, outputs 1.

An OR gate takes at least two inputs and outputs 1 if one of the inputs is 1.

Output Devices

Output devices transfer electrical energy into a response.

Buzzer

• Buzzers use electrical energy to create sound

• Most use a piezo transducer to convert current into movement into sound.

Speakers

• Speakers convert electrical energy to sound waves

Lamps

• Lamps convert electrical energy into light