TELEPHONE DIAPHRAGMS. 429 



Mechanics of the Receiver. 



The four essential and characteristic constants of any receiver, from 

 the electromechanical point of view, are as follows: 



A, the "force factor," or the electromagnetic pull, in dynes on the 

 diaphragm, per absampere ^ of alternating current, subject to the 

 restrictions that A varies somewhat with the frequency and strength 

 of the actuating current. The factor is supposed to be measured at a 

 standard frequency, and with feeble currents (less than 3 milliamperes). 



m, the "equivalent mass" of the diaphragm, or the mass, in grams. 



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Fig. 6. Fig. 7. 



Diagrams Illustrating a Telephone-Receiver Diaphragm Vibratory 

 System Considered as Replaced by its Equivalent Simple Vibrator. 



which, moving with the velocity at the center, has the same kinetic 

 energy as the whole diaphragm, with its actual distribution of mass and 

 velocities. 



r, the "motional resistance" of the diaphragm, in dynes per unit 

 velocity (cm. per sec), referred to the motion of the equivalent mass. 

 This force, due to internal friction, eddy-current losses, and air pro- 

 pulsion on the diaphragm, is assumed to be directly proportional to 

 the velocity, and dissipates the energy of motion. 



s, the "stiffness constant" or the force per unit displacement (dynes 

 per cm.), opposing the movement of the diaphragm, and referred to 

 the equivalent mass at the center. 



Thus in Fig. 6, the actual diaphragm, DD, clamped around the 



2 C. G. S. Magnetic units are used in developing the theory, throughout 

 this paper, with the distinguishing prefix ab- or abs-. The angle sign Z ap- 

 pended to the unit of an equation indicates that each term is a complex 

 quantity or "plane-vector." 



