Abstract: Magnetic field gradients are used e.g., for potential-free current measurement without voluminous ferrite cores to minimize the influence of homogenous external interference fields on the measurement. So far, they have been provided mainly through U-shaped primary current conductors. The aim is to make it unnecessary to guide high currents through U-shaped current conductors, and to provide a device and a method for creating one or more magnetic field gradients through a straight conductor. To this end, a primary current conductor which is straight at the point where the magnetic field is measured has a recess or groove or slot for creating a magnetic field gradient. Inside or in the area surrounding this recess, the field lines take a course that enables one or more gradiometers to be positioned so that the influences of especially homogenous interference fields on the measurements are successfully minimized using simple mathematical methods such as subtraction.

Abstract: The invention relates to a method for evaluating signals while eliminating an interference signal on magnetoresistive sensor elements which is preferably proportional to the zero offset. The sensor elements can form a sensor element array such as a sensor bridge. According to the invention, the direction of magnetization of the sensor elements is modulated or shifted by applying a magnetic pulse field of a modulated or variable direction, and the output signals of the sensor elements or of the sensor element array are fed to a differential amplifier. Due to the modulation or shift of the operating voltage of the sensor bridge, the modulation or shift resulting at the same time as the magnetization of the sensor elements, a signal often arises which includes a direct component that is proportional to the magnetic field to be measured, and has an alternating component that is proportional to the offset voltage of the sensor element array. The latter is minimized by a feedback or is adjusted to zero.