value closer to the average current in order to understand the operation of the magnetometer circuit in accordance with the present invention it is helpful to have simple model of the sensor behavior for example in magnetometer circuit 1 in fig1 a sensor l is a solenoidal inductor with a core 2 of saturable high permeability material a typical high permeability material suitable for the core 2 is a cobalt based amorphous metallic glass foil from allied signal product number 2705m a single winding 3 is used not only to provide the excitation signal but also to sense the changing field in the core the total magnetic field through the magnetic core material is the sum of the external magnetic field and the field created by current flowing through coil 3 the following equation describes this relationship where h is the total magnetic field through the core material 2 h e is the external applied magnetic field that is parallel to the core material 2 and i is the current flowing through the inductor coil 3 constant k 0 is a function of the physical parameters of coil 3 such as its turn density when a high permeability material experiences a magnetic field it effectively amplifies.