On the 17th October 1831, Michael Faraday designed the dynamo. He had devised a way of generating an electric current by the application of mechanical power. After much trial and error, Faraday finally succeeded in producing his designs and the dynamo was born.
He arranged a copper disc on a spindle which had a handle so that it could be rotated in between the poles of a strong magnet. The result was precisely what he expected. When two wires were transferred to a galvanometer (one rubbing on the spindle and one on the rim of the disc) a constant deflection was induced which demonstrated a continuous direct current.
Because eddy currents were produced in the copper disc, this first dynamo was extremely ineffective. However, a year afterwards, Hypolite Pixii of Paris fitted a pair of wire bobbins to a wooden gantry and then circled a horseshoe magnet beneath them. This was the first of many more experiments to be carried out using coils in various forms. They all helped lead up to the highly efficient dynamo we now have today.
Dynamos are mainly utilised in `Direct Current' circuits such as that found when a dynamo is used to power a bicycle lamp from tyre friction. For alternating current circuits the Alternator is used, this is the `AC' equivalent of the dynamo.
