Credited to Hungary. The dynamo-electric principle is usually credited to Werner Siemens and Charles Wheatstone, who published it in 1867. Jedlik's machine dates to about 1861 but he did not publish it in a scientific journal; it is recorded only in a university inventory. His priority is accepted by sources such as the Linda Hall Library, though it had no influence on later development.
How it began
Anyos Jedlik (1800 to 1895) was a Benedictine priest and physicist who joined the faculty of the University of Pest in 1840. He began experimenting with electric motors in 1827 and in 1828 built an electromagnetic rotor with a stator, a rotor and a commutator, all relying on electromagnets. About 1861 he built a small machine he called a unipolar inductor, or single-pole electric starter, which worked as a dynamo. He first mentioned it in writing in 1861, in an inventory list of the university.
How it works
In Jedlik's prototype both the fixed and the turning parts were electromagnets. Two opposed electromagnets set up the magnetic field around the rotor in place of permanent magnets. As one side of the rotating coil passes the north pole it cuts the lines of force and a current is induced. The current falls as the coil turns on, then rises in the opposite direction at the south pole. A commutator keeps the current flowing one way in the outside circuit. The machine's own current feeds its field magnets, which is called self-excitation.
Who pushed back
Jedlik chose not to publish his motors or his dynamo in any major scientific journal, and the invention went unnoticed at the time. Werner Siemens and Charles Wheatstone published descriptions of the dynamo-electric principle in 1867, and it is with their names that the principle became known.
Where it stands today
Jedlik is regarded in Hungary and Slovakia as an unsung father of the dynamo and the electric motor. His 1828 electromagnetic rotor survives. One source places it in the Museum of Applied Arts in Budapest and another says it was kept in the physics laboratory of the Benedictine house at Pannonhalma.
