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Electromechanical components

An electromechanical component is one that uses an electrical signal to cause some kind of mechanical change, such as a motor turning. These usually use an electrical current to create a magnetic field which causes a physical movement. I have included relays (of all kinds) within this category as these are often based around a mechanical switch, although some solid-state relays are also available.


A relay is an electrically operated switch.

A current is passed through a mechanical coil on one side of the relay which causes switch contacts to move on the other side. There is no electrical connection between the input and output, so a relay is often used to switch electrical circuits involving higher voltages than the input signal. A common use is in switching mains electricity or for use in cars to switch the noisy electrical supply.

Reed relay

A reed relay is a relay that uses a reed switch instead of a mechanical arm operated switch. These are only suitable for switching small loads, but can often be driven directly from a smaller signal such as the output from an Arduino or from the PiFace digital.

For an example project using a reed relay see home automation (Raspberry Pi) or home automation (arduino) projects.


An electrical motor uses an electrical current to induce a magnetic field that causes it to rotate. A standard DC motor is driven using a direct current. If the direction of the current is reversed then the direction of rotation will also be reversed.

There are other types of motors including servo motors and stepper motors

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