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connected by wires 18 and 19 to any suitable electrical device 20, which may be a receiver or an amplifier. The battery 15 is connected by a wire 21 to a pin 22 extending through the screw plug 11. The back of the metallic casing 1 is covered and the parts exposed thereon are enclosed by a thin metal shell 23 fastened to the casing by any suitable means, such as a set screw 24. In order to provide that the diaphragm 10 shall vibrate only to those frequencies which lie within a narrow and desired range, I pass a pin 25 through the central portion of the diaphragm 10 and on this pin I dispose a plurality of washers 26, preferably of lead, so as to weight or load the diaphragm 10. This loading of the diaphragm will slow down the sensitiveness of the diaphragm to other vibrations than those of low frequency. It will thus be seen that in the transmitting device above described there is an air chamber to the left of the diaphragm 10 containing the carbon buttons and a dead air chamber to the right of the diaphragm 10 and between it and the diaphragm 4 into which the load elements, such as the pin 25 and washers 26, extend. The pin or bolt is preferably formed of brass. As the thin diaphragm 4 is placed against the organism, the movement or vibration of which is to be measured, the air within the chamber contained between this diaphragm and the diaphragm 10 will be moved by the movement of diaphragm 4 and cause a |
movement of the diaphragm 10 which is regulated or limited by the depression of the weight in the form of the plurality of washers on this diaphragm. Therefore, the loaded diaphragm will respond to the particular vibrations to which it is sensitive and will so affect the carbon cells or buttons as to cause a variation of current in the circuit which may be received or amplified as desired. What I claim is:-- 1. In an electrical stethoscope device, means for providing a dead air chamber, a thin diaphragm forming one end wall of the dead air chamber said diaphragm being mounted for free vibratory motion and adapted to freely transmit vibrations to the dead air chamber, a weighted diaphragm forming the other end wall of the chamber, and means whereby vibrations of the last named diaphragm may be converted into electrical signal currents. 2. An electrical stethoscopic device which includes a sound chamber, a thin diaphragm across one end of said chamber, a metallic diaphragm disposed across the other end of said chamber, rod extending through said diaphragm into said chamber, and a plurality of weights disposed on said bar to vary the sensitiveness of the diaphragm to vibrations produced in the chamber by vibrations of the first mentioned diaphragm when placed against a vibrating organism. RAYMOND BARRINGTON ABBOTT. |