ABSTRACT
Electricity can be dangerous. My nephew tried to stick a penny into a plug. Whoever said a penny doesn’t go far didn’t see him shoot across that fl oor. I told him he was grounded. —Tim Allen, comedian
An alternating current (AC) power supply can be thought of as a power converter; its job is to convert the line level AC power to another form which is more useable for the load with as little loss as possible. The fi rst law of thermodynamics is the conservation of energy, which says that energy can neither be created nor destroyed; it can only change forms. The main function of a power supply is to convert electrical energy from a certain voltage, current, and frequency to electrical energy with a different voltage, current, and possibly a different frequency. Except for the losses due to ineffi ciency, energy is conserved in the process of conversion.
