An electric generator is disclosed having a high efficiency over wide ranges in rotor speed and power output requirements. Output voltage control is achieved by providing the power output windings with variable adjustment. This variable adjustment determines the number of turns that are used for the power output on the power output windings themselves. When excess voltage is generated, turns used on the power output windings are reduced thereby reducing output voltage and increasing efficiency by lowering the power output winding resistance. When the voltage generated is low, more turns on the power output windings are activated thereby increasing the voltage of the generator itself. This voltage control occurs prior to any voltage modification outside of the generator. A sensor and feedback mechanism is used to automatically adjust the power output windings thereby attaining maximum efficiency at the desired voltage and power level.