generator 3 fig1 b illustrates an enlarged detail of fig1 a fig1 c 10 d and 10 e illustrate cross sections of the generator in different movement phases of the rotor 7 the stator 5 in fig1 a 10e is formed with one magnetic return disk 69 above the magnet 13 and one below the magnet the rotor 7 with the magnetic return yoke 71 can move completely through the stator 5 in the exemplary embodiment in fig1 a 10e in comparison with the exemplary embodiment in fig9 this has the advantage that a movement of the lifting rod 59 is not impaired and that higher voltages can be induced in the coil 11 as a result of a higher possible frequency of the fluctuation of the magnetic lines of force 17 as is shown in fig1 a 10e a cylindrical configuration of the components of the rotor 7 and the stator 5 can be advantageous by virtue of the magnetic return yoke 71 it is possible to realize the regions 51 53 of different geometric configuration or different magnetic permeability on the rotor 7 the magnetic return yoke 71 can consist of a material with a high magnetic permeability in addition the magnetic return yoke 71 can be realized as part of the lifting rod 59 by virtue of the movement 63 of the alternately tapered magnetic return yoke 71 the reluctance of the magnetic circuit changes as a result the magnetic flux varies and a voltage is induced in the coil 11 the rotor 7 can be considered to be a u201c magnetic valve u201d which can inhibit the development paths of the magnetic flux in the manner.