Abstract: A compact, power-sparing detector for detecting heart polarizations is described. The detector has a first operational amplifier which uses sensed heart signals from a heart as an input signal. By means of feedback coupling via a second operational amplifier, a resistor and a capacitor, the system strives to achieve a minimum voltage gradient across the input terminals of the first operational amplifier. When an electrical signal with a signal slope corresponding to a heart depolarization arrives at the input terminal of the first operational amplifier, the second operational amplifier is no longer able to damp the input signal, and a peak output signal is sent from the first operational amplifier to each of a first comparator and a second comparator, respectively.