Magneto-Electric Machine
   Davis built two Magneto-Electric Machines: one, producing an alternating current, was used to produce shocks, while the other was designed to produce a pulsating direct current. This could be used for running a decomposing vessel in which water was electrolyzed into hydrogen and oxygen. Two examples of the latter type of machine are shown below. The alternating EMF produced as the multi-turn coils sweep past the poles of the compound permanent magnet is turned into what we would now call a full-wave rectified signal by a pole-changer or commutator. The device cost between $30.00 and $35.00 in 1842.
                                Allegheny College                                                                      Grinnell College

You may want to see information about other magneto-electric machines.

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