Abstract: A circuit system and a method for operating an electric motor having variable speed from a direct-voltage source is proposed, in particular for operating a cooling air fan motor of a motor vehicle from the vehicle's electrical system. The circuit system uses pulse-width-modulated input signals that are provided by a control unit, and enables, through integration and threshold value comparison of the signals, an operation of the electric motor with different speeds based on differentiated series resistor connection, corresponding to the pulse-duty ratio of the pulse-width-modulated input signals.

Abstract: The invention relates to a method for expanding the absolute angle measurement range in magnetic field sensors. Through the use of an evaluation circuit (12), various method steps are carried out; first, the ratio of two phase-shifted input values is determined, for example sine signals or cosine signals of the voltage (2, 3). The ratio of the phase-shifted input values (2, 3) to each other is combined with an offset C. The predeterminable offset C permits the expansion (9) of the angle measurement range of magnetic field sensors to a full 360° rotation (11) or a multiple thereof.

Abstract: The invention relates to a method for expanding the absolute angle measurement range in magnetic field sensors. Through the use of an evaluation circuit (12), various method steps are carried out; first, the ratio of two phase-shifted input values is determined, for example sine signals or cosine signals of the voltage (2, 3). The ratio of the phase-shifted input values (2, 3) to each other is combined with an offset C. The predeterminable offset C permits the expansion (9) of the angle measurement range of magnetic field sensors to a full 360° rotation (11) or a multiple thereof.