This little machine generates DC power from a source such as a stream running down a hillside. Water is channelled into a pipeline with enough drop (head) to build up sufficient pressure. It can also be used with water systems that are under pressure like the water in city supplies. The water passes through a small nozzle where it gives up pressure for velocity. The water then passes through the turbine runner which converts the energy in the water into shaft power and spins the generator. This electric power is first alternating current (AC) that is converted into direct current (DC) with a device called a rectifier.