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Electrical circuit components

Electrical circuit componentsWant to become an electrical engineer? Find out more about electrical components.

Capacitors: Capacitors store electric charge. They can be used in timing circuits because, depending on the size of the capacitor, it will take a certain amount of time to fill with charge. They can be fixed, pre-set by the user, or variable.

Cells and batteries: These are the source of direct current (d.c.) to an electrical circuit. They come in two different types: disposable and rechargeable. They hold charges of between 1.5 and 2 volts, although a larger voltage can be achieved by connecting batteries together in relay.

Circuit breakers: A circuit breaker has a similar purpose to a fuse – it is there to protect the circuit from faults. The main difference is that fuses are designed to destroy themselves (melt) when they detect a fault in the circuit. Circuit breakers, however, can be reset even once they have broken the circuit. They also tend to be sensitive to smaller changes in currents.

Diodes: Diodes are used to transfer a.c. into d.c. and they allow current to flow only in one direction. In this way they work like a valve. A valve in a system of pipes can stop liquid flowing in the opposite direction, just like a diode can ensure that current in a circuit only flows one way. A diode usually has two electrodes – the anode and the cathode.

Fuses: In simple terms, a fuse is a thin wire which melts when too much current flows through it. Fuses are used to protect circuits from faults, such as when too many appliances are connected to one circuit.

Inductors: An inductor is an electrical component that can store energy from the circuit in a magnetic field. It is usually a wire shaped as a coil, which creates a magnetic field as the current passes through it. Inductors are used to limit the build-up of alternating current (a.c) in a circuit, and to keep the circuit running when the supply is switched off.

Integrated circuits: An integrated circuit is one which contains many of the components in this list. Integrated circuits are often printed on small slices of silicon, which can be placed in anything from mobile phones to washing machines. Microprocessors are good examples of this.

Motors: Motors are output devices which produce motion. A simple example of this would be an electric fan – when the current runs through the circuit, the motor moves and turns the blades of the fan.

Relays: A relay is another kind of switch. It is under the control of another electrical circuit, which tells it when to open and close. There are two different types of relay. Electromechanical relays are controlled by a coil which generates an electromagnetic current. Solid-state relays use a semiconductor switching device.

Resistors: A resistor opposes the current running through an electric circuit. The value of its resistance can be set by the user, or variable. Sometimes simple resistance wire is used in place of resistors. This wire can be made from an alloy such as nickel or chrome, which has high resistance to current.

Sounders: These are output devices which produce sound. One of the simplest examples of a sounder is the doorbell.

Switches: These control the flow of current in a circuit. Switches are binary, which means they can only be one of two things: open or closed. An open switch will not allow the flow of current. A closed switch means that the space between the two contacts is ‘closed’ and current can flow freely.

Transistors: A transistor is a semiconductor device used to amplify or switch electronic signals. A transistor can amplify because its output can be much bigger than its input.

Transformers: Transformers are designed to convert alternating current from one voltage to another. They are used to transfer electrical energy between two circuits. A transformer consists of two wire coils wrapped around a core. The wire coils create electromagnetic fields, and the changes in these fields help to transfer the energy.

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