An electrical device comprising a brushless one-phase driving motor and a mechanical unit being driven by the driving motor, the driving motor comprising a motor rotor being radially permanently magnetized and rotating around a rotational rotor axis, a non-symmetric stator back-iron structure with a lateral bridge portion magnetically connecting two stator poles (41, 42), and with a rotor opening for the motor rotor, wherein the back-iron structure is provided with a non-cylindrical rotor opening provided with two axial recesses (46,47) being geometrically opposed with respect to the rotor axis, a single stator coil surrounding the bridge portion, a pole separation gap radially opposite to the lateral bridge portion and magnetically separating the stator poles (41, 42), an electronic control device comprising several power semiconductors for driving the stator coil, and for commutating the electric energy driving the stator coil, and a single hall sensor which is electrically connected to the control device, wherein the hall sensor is arranged approximately radially opposite to the stator coil with respect to the rotor axis wherein the motor rotor defines exactly two magnetic poles (31, 32), wherein the normal of the active plane of the hall sensor is crossing the rotational rotor axis, wherein the hall sensor sees the radial magnetic field of the motor rotor, and wherein the hall sensor is positioned outside of the cross plane defined by the motor rotor, and wherein the hall sensor is not arranged in an angle of 180° but is arranged within an angle of 160° to 200° seen from the middle of the stator coil and with reference to the rotor axis, so that the hall sensor rotational position exactly corresponds with the commutation moment, so that the hall sensor generates a commutating signal which directly drives the electronic control device. a motor rotor being radially permanently magnetized and rotating around a rotational rotor axis, a non-symmetric stator back-iron structure with a lateral bridge portion magnetically connecting two stator poles (41, 42), and with a rotor opening for the motor rotor, wherein the back-iron structure is provided with a non-cylindrical rotor opening provided with two axial recesses (46,47) being geometrically opposed with respect to the rotor axis, a single stator coil surrounding the bridge portion, a pole separation gap radially opposite to the lateral bridge portion and magnetically separating the stator poles (41, 42), an electronic control device comprising several power semiconductors for driving the stator coil, and for commutating the electric energy driving the stator coil, and a single hall sensor which is electrically connected to the control device, wherein the hall sensor is arranged approximately radially opposite to the stator coil with respect to the rotor axis wherein the motor rotor defines exactly two magnetic poles (31, 32), wherein the normal of the active plane of the hall sensor is crossing the rotational rotor axis, wherein the hall sensor sees the radial magnetic field of the motor rotor, and wherein the hall sensor is positioned outside of the cross plane defined by the motor rotor, and wherein the hall sensor is not arranged in an angle of 180° but is arranged within an angle of 160° to 200° seen from the middle of the stator coil and with reference to the rotor axis, so that the hall sensor rotational position exactly corresponds with the commutation moment, so that the hall sensor generates a commutating signal which directly drives the electronic control device.