AN ELECTRONIC PHONOCARDIOGRAPH EMPLOYING A DOUBLE-BEAM CATHODE-RAY OSCILLOGRAPH AS THE RECORDING DEVICE

Abstract

Circuit diagram and frequency response curves of an adaptable apparatus for general-purpose phonocardiography are given. The instrument employs crystal microphones, electronic amplification, and double-beam cathode-ray tube recording. Either the venous pulse or the ecg. is recorded simultaneously with the heart sounds.