English: Drawing of a Gramme dynamo, an electrical generator designed by Belgian inventor Zénobe Gramme in 1871. It was the first machine to be used industrially to generate power. His innovation was to use many armature windings (30 in this machine), wound on a doughnut shaped armature, and switched with a many segmented commutator, to smooth the output waveform, producing nearly constant DC power. This drawing shows a hand cranked model from the 1870s used widely in laboratories, text says it's output was equivalent to "eight ordinary Bunsen elements [batteries]". It used laminated permanent magnets invented by Jamin.