Electrical and electronic components, devices, and systems

Basics of Electricity

Electricity is a form of energy resulting from the existence of charged particles like electrons and protons, either static or moving.
Current (I) is the amount of charge passing through a specific point in a circuit per second. It is measured in Amperes (A).
Voltage (V) is the electrical force that drives the current around the circuit. It is measured in Volts (V).
Resistance (R) is opposition to the flow of current and is measured in Ohms (Ω).
The relationship between these three factors is given by Ohm’s Law, which states that V=IR.

Resistors limit the flow of current in a circuit. The higher the resistance, the less current flows for a given voltage.
Capacitors store electric charge. They are used in filtering, tuning circuits and time-delays.
Inductors store energy in their magnetic field and are commonly used in tuned circuits and for power supply smoothing.
Diodes allow current to flow in one direction only.
Transistors are devices that can amplify an electrical signal or act as an electronic switch.
Integrated Circuits (ICs) contain many transistors, resistors, diodes and other components, offering complex functions in a small package.

Power Supplies convert electricity from one form to another - often from AC to DC.
Oscillators generate a repetitive signal, usually a sine wave or square wave.
Amplifiers increase the magnitude of a signal.
Filters remove or enhance frequencies in electronic signals.
Logic gates are fundamental building blocks of digital circuits.

Series circuit: Components are connected end-to-end so the same current flows through each one.
Parallel circuit: Each component is separately connected to the power source, so the voltage is the same across each one.
Complex (Mixed) circuit contains combinations of series and parallel connections.
Digital Systems: Utilise digital signals that represent binary numbers, zeros and ones.
Analogue systems: Utilise signals that are a continuous waveform.
A Transducer converts one form of energy to another - for example, a microphone converts sound waves into electrical signals.
Relays and Contactors are electrically controlled switches used for controlling large power loads.