Abstract: A magnetoresistive transducer bridge is operated in a saturation mode by an AC signal in an adjacent conductor. The field produced by the AC signal in the adjacent conductor is of sufficient amplitude to magnetically saturate the bridge elements in a pair of opposite arms of the bridge during most of each half cycle of the AC signal. During each zero-crossing of the applied signal, the bridge comes out of saturation and produces a signal pulse. Thus constituting a zero-crossing detector. This response characteristic is utilized in circuitry producing a current-presence detector, a signal amplitude detector, and a power-factor detector.