DC Power Supply
An electronic power supply, often referred to somewhat incorrectly as an AC adaptor, is an electronic device that produces direct current of a particular voltage and current from a source of electricity such as a battery or wall-socket power. The direct current (DC) is usually used to power the internal circuits of an electronic device, such as a computer.
A simple AC powered linear power supply uses a transformer to convert the alternating current from the wall to the desired voltage. An array of diodes then rectifies the alternating current to direct current. Finally, a low-pass filter smooths out the high-frequency ripple that is left after the rectification.