Abstract: A simple, reliable and sensitive electrical circuit for detecting when a first input exceeds a second input and vice versa and producing corresponding signals at first and second outputs comprising first and second operational amplifiers each having its negative input connected to its output and its positive input serving as a circuit input to function as a voltage follower, first and second comparator circuits with the positive input to the first comparator being directly connected to the output of the first amplifier and the negative input to the output of the second amplifier via voltage dividing resistors so that the output thereof goes to zero when the output of the first amplifier drops below the divided output of the second and with the second comparator similarly connected so that the output thereof goes to zero when the output of the second amplifier drops below the divided output of the first amplifier.