A power supply is an electronic device that supplies electric energy to an electrical load. The primary function of a power supply is to convert one form of electrical energy to another. As a result, power supplies are sometimes referred to as electric power converters. Some power supplies are discrete, stand-alone devices, whereas others are built into larger devices along with their loads. Examples of the latter include power supplies found in desktop computers and consumer electronics devices.
A Video Distribution Amplifier (also known as a distribution amp or VDA) takes a video signal as an input, amplifies it, and outputs the amplified video signal to two or more outputs. It is primarily used to supply a single video signal to multiple pieces of video equipment. It adjusts the amplitude of a video signal to compensate for loss of signal in a video distribution system. Extending the distance of the video signal is the main purpose of the VDA. There are VDAs built for all video formats, NTSC, ATSC, QAM16, QAM32, QAM64, Composite Video and Component Video.
Their construction and capabilities can be simple; accept input signal, amplify, then output. Others can be more sophisticated that allow remote control from a control station, allow adjustment of the gain, equalization, and provide status of the input and output signals through Ethernet networks.