User Manual
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Component Introduction
Relay:
A relay is an electrically operated switch. Many relays use an electromagnet to
mechanically operate a switch, but other operating principles are also used as in
solid-state relays. Relays are used where it is necessary to control a circuit by a low-
power signal (with complete electrical isolation between control and controlled
circuits), or where several circuits must be controlled by one signal. The first relays
were used in long-distance telegraph circuits as amplifiers. They repeated the signal
coming in from one circuit and re-transmitted it on another circuit. Relays were used
extensively in telephone exchanges and early computers to perform logical
operations.
A type of relay that can handle the high power required to directly control an electric
motor or other loads is called a contactor. Solid-state relays control power circuits
with no moving parts, instead using a semiconductor device to perform the
switching. Relays with calibrated operating characteristics and sometimes multiple
operating coils are used to protect electrical circuits from overload or faults. In
modern electric power systems, these functions are performed by digital
instruments called "protective relays".
Below is the schematic of how to drive relay with Arduino
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