At its core, a 12-volt relay is an electromagnetic switch used to control electrical circuits. It consists of a coil (which is typically energized with a 12V DC power source), contacts, and a magnetic armature. When the 12-volt signal is applied to the relay’s coil, it generates a magnetic field that pulls or releases the armature. This movement of the armature either closes or opens the contacts, completing or breaking the circuit connected to the load.

    The main advantage of using a relay is that it allows a low-power control circuit to control a high-power circuit, which is important for safety, efficiency, and ease of use. For example, a low-voltage signal from a car's dashboard can activate the relay to turn on the headlights, which operate on a higher voltage.