Abstract: A playback circuit for use with a magnetic recording transducer, in a magnetic recording apparatus, the transducer developing an alternating current readback signal having alternating positive and negative peaks, the playback circuit comprising a differentiator responsive to the readback signal and operative to produce a differentiated signal having first and second polarities and having zero crossings in time coincidence with the positive and negative peaks, a bidirectional one-shot device responsive to the differentiated signal and operative to produce a first bistate signal having transitions in time coincidence with the zero crossings and to produce a second signal comprising a sequence of pulses having leading edges that correspond in time to the zero crossings and having trailing edges that lag the leading edges by a predetermined time interval, a latch for producing a third signal having transitions that correspond in time to the trailing edges and having a level that corresponds to the level of the fi