Electromagnetic machine, or dynamo

Command of electricity breathed new life into industrial development in the second half of the 19th century. In 1871 the self-taught Zénobe Gramme perfected existing electromagnetic machines. Two electromagnets forming an inductor produced a large magnetic field. A ring of wire wound with coils (Pacinotti's ring) rotated between the magnets, causing variations in magnetic flow that generated alternating current. Brushes picked up the current, which was then transmitted to collectors on the ends of the coil. Their position in relation to the collector's blade made it possible to transform the alternating current into direct current. In 1873 Hippolyte Fontaine demonstrated the reversibility of the dynamo, which, used as an engine, had many industrial applications.