Abstract: A circuit having an amplifier coupled to an oscillator, the oscillator having a second amplifier and a feedback circuit. Changes in resistance between an electrode coupled to the circuit and a probe, also connected to the circuit, are responded to by the circuit. Output components are connected to the circuit for providing visual and audio signals corresponding to the resistance changes and for recording the changes upon a chart. The electrode is grasped by a patient, and the probe is the hand of a doctor using the technique of palpation upon the patient.