SLOPE POLARITY DETECTOR CIRCUIT

An electrical circuit for determining the polarity of the slope of an analog type voltage waveform includes a voltage comparator and time delay network providing a time delay of less than 0.05 times the period of one cycle of the voltage waveform being monitored. In a positive slope detector circuit, the analog input signal is supplied to the positive input terminal of the comparator and is also supplied through the time delay network to the negative input terminal. In a negative slope detector circuit, the time delay network is connected to the positive input terminal. A circuit including both the positive and negative slope detector circuits, and a logic gate connected to the outputs of the detector circuits, provides the function of a zero slope detector.