A 12V relay is an electromagnetic switch that uses a small 12-volt electrical signal (like from a dashboard button) to control a much larger, separate high-current circuit, allowing you to safely operate accessories like headlights, horns, or motors without overloading the low-current switch or wiring. It works by energizing a coil, which creates a magnetic field that pulls contacts to complete the high-current circuit, effectively acting as a remote, heavy-duty switch.�
Relays are most commonly used switching device in electronics. There are two important parameters of relay, first is the Trigger Voltage, this is the voltage required to turn on the relay that is to change the contact from Common → NC to Common → NO. The other parameter is your Load Voltage & Current, this is the amount of voltage or current that the NC, NO or Common terminal of the relay could withstand, in our case for DC it is maximum of 30V and 10A. Make sure the load you are using falls into this range.
Relays are switches controlled by electrical power, like another switch, computer or control module. The purpose of a relay is to automate this power to switch electrical circuits on and off at particular times.
Relay Pinout Configuration
Pin 1(Coil End 1) Used to trigger(On/Off) the Relay, Normally one end is connected to 12V and the other end to ground
Pin 2(Coil End 2) Used to trigger(On/Off) the Relay, Normally one end is connected to 12V and the other end to ground
Pin 3(Common(COM))Common is connected to one End of the Load that is to be controlled
Pin 4(Normally Close (NC))The other end of the load is either connected to NO or NC. If connected to NC the load remains connected before trigger
Pin 5(Normally Open (NO))The other end of the load is either connected to NO or NC. If connected to NO the load remains disconnected before trigger
Applications
Commonly used in switching circuits.
For Home Automation projects to switch AC loads
To Control (On/Off) Heavy loads at a pre-determined time/condition
Used in safety circuits to disconnect the load from supply in event of failure
Used in Automobiles electronics for controlling indicators glass motors etc.
