A relay is a switch which is operated by electricity. Current flowing through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts. The coil current can be on or off so relays have two switch positions and most have double throw (changeover) switch contacts as shown in the diagram. Relays allow one circuit to switch a second circuit which can be completely separate from the first. Railwayscenics supply an wide range of relays and bases including latching, non latching, miniature, plug in and sub miniature, along with some relay bases. All the range is competitively priced and ready for delivery.