Power supplies refer to compact electronic units that plug into the mains and deliver power suitable for specific applications. They are also referred to as power packs. Generally, power supplies are used for converting high voltage AC to low voltage DC. They are also used for converting energy from one form such as mechanical, thermal, chemical and solar to electrical energy.
Usually, a power supply has an inherent regulatory mechanism for controlling its output current, voltage or both depending on the particular application. The circuitry of the power supply strives to maintain the output constant in spite of any fluctuations in the input supply voltage or the load connected to it, within a certain range.
