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 , 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 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 , 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 , 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 , 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 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 , 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 , 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 . <EOS>