GB429748A - - Google Patents

Abstract

Abstract 429,748. Circuits for stethoscopic &c. apparatus. MACNAUGHTON, F. G., 69, Evington Road, Leicester, and McCARTNEY, M., 147, Burnt Ash Hill, Lee, London. Oct. 4, 1933, No. 27234. [Class 40 (iv)] [See also Groups VI, XXXVI, and XXXVIII] An apparatus for investigating sounds (and electrical impulses) produced by different parts of the body comprises a microphone for collecting the sounds (e.g. cardiac sounds), an amplifier for the microphone currents, a cathode ray oscillograph for visually analyzing the sounds and a telephone by which they are simultaneously rendered audible. Electrodes are provided whereby currents from the body may be used to operate an oscillograph simultaneously or alternatively with the sound operated oscillograph. Records of the oscillations may be obtained by the use of suitable photographic apparatus. In the arrangement shown diagrammatically the output of microphone s is connected to a switch c from which leads pass to amplifiers e, f, g. Electrodes d are also connected to the switch. The switch is so arranged that the following circuits may be made effective.-(1) microphone s connected through amplifier f to a telephone i; (2) microphone s connected through amplifier e to an oscillograph k; (3) microphone connected through amplifiers e and f to oscillograph k and telephone i; (4) electrodes d connected through amplifier g to oscillograph l; (5) the circuits of (3) and (4) may operate together. Known time-base circuits y, i enable a visual indication of the sound to be seen on the face of the oscillograph but when it is desired to record the trace of the sound or electrical impulse photographically on a moving plate or film the time-base circuits are dispensed with. The microphone preferred for use in the apparatus comprises a case r containing a known sensitive element (e.g. carbon block and granules, a moving coil or condenser) a flexible diaphragm n and a disc p carried by a rod o projecting from the diaphragm and adapted for contact with the patient's body.

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Bibliographic Details