Abstract: A detector for determining whether the time duration between a positive and a negative peak of a waveform is greater or less than a predetermined time interval comprises a delay line for delaying the waveform by the predetermined time interval. A peak detector of a first polarity for detecting the first occurring peak of the waveform is responsive to the delayed waveform to provide a signal upon the occurrence of the first occurring peak thereof. A peak detector of a second polarity for detecting the second occurring peak of the waveform is responsive to the undelayed waveform for providing a signal upon the occurrence of the second occurring peak thereof. A time sequence comparator provides a first output indication when the signal from the first peak detector occurs prior to the signal from the second peak detector and a second output indication when the signal from the second peak detector occurs prior to the signal from the first peak detector.