Step voltages up or step voltages down, by transformer action, to the required AC line voltage. Change AC voltage to pulsating dc voltage by either half-wave or full-wave rectification. Whether you need high-voltage power on board a ship or need to plug in a notebook computer to charge, you need a power supply. Because not all models are the same, you need to know what. What is a Power Supply? A power supply is an electronic circuit designed to provide various ac and dc voltages for equipment operation. The objective of a power supply is to. In Japan, the "2018 Hokkaido Eastern Iburi Earthquake" that occurred on September 6, 2018, and typhoon No. 15 in 2019 brought about a "blackout" that caused the power supply to completely stop. In the most basic terms, electricity is the movement of electrons.