Power Transformers

Transformers are electronic devices that transfer alternating (AC) electric energy from one circuit into another through producing electromagnetic induction. These transformers mainly consist of a ferromagnetic core and two or more coils. Transformers work by a changing current in the primary winding creates an alternating magnetic field in the core. The core multiplies this field and couples the most of the flux through the secondary windings. This in turn induces alternating voltage in each of the secondary coil according to Faraday's law.

Power transformers are designed to change amplitude of high-frequency pulses by the turn’s ratio and to provide isolation between circuits. Note that it can't transfer a DC component of the pulse voltage: in a steady state mode net volt-seconds across each winding should be zero, otherwise the core will saturate. DC output voltage is obtained only by using rectifiers. Note that an average voltage across a real coil's terminals can be non-zero due to non-zero coil's resistance.