The transformer has a primary designed for either 120 or 230 volts, and a secondary that delivers 115 ... usually the job of a second 6- or 12-volt winding on a power transformer.

Dilshan Jayakody, CC BY-SA 2.0. How does a transformer work? An alternating current in a primary winding induces an opposite current in its secondary winding. The voltage out is equal to the turns ...