Abstract: The invention concerns a device comprising a fixed supporting structure (5) on which a plurality of permanent magnets (14-29) is provided, which surround at least partially a rotating shaft (32) supporting a rotor (2?) provided with a group of magnets (13) adapted to interact with the magnetic field generated by the plurality of permanent magnets (14-29) of the fixed supporting structure (5), so that to produce a rotation of the rotating shaft (32) which allows an alternator (1) to be activated, where the device (100) further comprises a swinging-lever assembly (40) provided with a plurality of magnets designed so that traction and/or thrust effects are generated on the group of magnets (13) by the rotor (2?) connected to the rotating shaft (32).