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May 1925


Author Affiliations

Professor of Pediatrics; Professor of Electrical Engineering SENDAI, JAPAN
From the Pediatric Department of the Medical College, and the Electrical Engineering Department of the Technological College of the Tohoku Imperial University.

Am J Dis Child. 1925;29(5):618-620. doi:10.1001/archpedi.1925.04120290039006

At the fifty-sixth regular meeting of the Tohoku Medical Society held Dec. 20, 1924, we made the first report on our electrical stethoscope which we named "magnoscope."1 The following short excerpt from our report will show that our instrument has been developed independently of the stethophone,2 the details of which we were only able to learn several days previous to making our report.

Our purpose was to amplify those sounds auscultated through an ordinary stethoscope, and to reproduce them faithfully with definite filtering as a special object.

Our method is an application of the principle of the triod valve amplifier. Our present arrangement consists of:

1. Transmitter: Telephone receiver of moving coil type specially made for magnoscope.

2. Three-stage triod value amplifier: Transformer coupling with tuning condensers.

3. Receiver: Telephone receiver of moving coil type specially made for magnoscope.

After explaining the principles of the apparatus, we demonstrated

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