What is a Relay? : Ard Relay bir is an electrical switch that enables another electrical circuit to open and close. This switch is controlled by an electromagnet. It was invented by Joseph Henry in 1835.
The contacts of the relay can be normally open (NC Normally Open - NO “), normally closed (” Normally Closed - NC “) or in the contact.
Relays look like a transistor task, for example when you supply current on a simple 3 leg relay, the arm on the chassis opens the current on the other side, ie it can be used for control.
There is only one difference from transistors: no need to use with resistance. When the coil is magnetizing the two contacts, a contact of the relay closes a contact.
The relays are an electromagnetic switch that operates with low currents. When a voltage is applied to the electromagnetic coil on the electromagnetic coil, the coil gains the magnet feature and acts as a key by pulling a metal palette facing the opposite one by connecting one or more contacts to one another.
Relays which have lost their popularity after the production of thyristors and triacs are still used in many areas. The only advantage of thyristors and triacs is that they can have more than one switch contact in a single structure, so they can open or close multiple loads at the same time, or even open and close some loads at the same time. This process is entirely related to the design of the contacts of the relay. The relays can be used for both AC and DC operation. Generally; relays are divided into two as switches and measuring relays. Also; The relays are grouped according to the operation, the purpose of use and the way they are connected to the circuit.