Abstract: A magnetic proximity sensor for detecting the proximity of a laterally mog magnetized target moving along a translation axis which is parallel to a line joining the targets magnetic poles, including: two ring-core flux-gate magnetometers disposed adjacent to each other with their axes of sensitivity in parallel, with both axes perpendicular to the magnetized target translation axis. The energizing coils of the flux-gate magnetometers are driven by an ac signal at frequency f.sub.o. The signal on the detecting coils in each flux-gate magnetometer is applied to a phase comparator via a bandpass filter tuned to the second harmonic of f.sub.o. When the signals applied to the phase comparator are of opposite phase, then the center plane equidistant from the target's magnetic poles is between the two axes of sensitivity of the magnetometers. When the signals are of the same phase, then the target's center plane is laterally outside of the these two axes.

Abstract: A proximity sensor for indicating the spatial proximity of a ferrous object omprising a magnetic reluctance bridge formed from a plurality of high and low permeability sections and with a ring core flux gate magnetometer disposed therebetween to form the center reluctance path of the bridge in order to sense flux when the bridge is unbalanced, a dc magnetic field generator disposed along a line of symmetry for the bridge for providing magnetic flux in the bridge, wherein a ferrous object disposed adjacent one of the low permeability sections will unbalance the bridge and cause flux to be detected by the flux gate magnetometer, and further including circuitry for generating a triggering signal when flux is detected by the magnetometer.