Transformers
                Transformers are electronic devices that change an electrical current. Magnetic induction is used between the coils to current and voltage levels.  There are many kinds of transformers; Audio Transformers, Auto Transformers, Constant Voltage Transformers, Current Sense Transformers, Current Transformers, IF Transformers, Inverter Transformers, Other Transformers, Power/Mains Transformers, Pulse/Datacom Transformers, RF Transformers, SMPS Transformers, Telecom Transformers,  and Variacs.