Magneto-electric machine of Nollet and Van Malderen for producing induction currents. A magneto is an electrical generator that uses permanent magnets to produce periodic pulses of alternating current. Unlike a dynamo, a magneto does not contain a commutator to produce direct current. Magnetos have advantages of simplicity and reliability, but are limited in size owing to the magnetic flux available from their permanent magnets. The fixed excitation of a magneto made it difficult to control its terminal voltage or reactive power production when operating on a synchronized grid. This restricted their use for high-power applications. Power generation magnetos were limited to narrow fields, such as powering arc lamps or lighthouses, where their particular features of output stability or simple reliability were most valued. Illustration appeared in "Electricity and magnetism" ny Amedee' Guillemin, 1891. This image has been color enhanced.