AN IMPROVED TELEPHONE SET 265 



electrically whether the armature responds to direct current equivalent in 

 effect to the required operate and non-operate 20-cycle alternating current 

 values. This is accomplished by focusing a light beam on the clapper ball 

 in such a manner that a photoelectric cell underneath will indicate the 

 position of the clapper and hence of the armature. This procedure of alter- 

 nating magnet and biasing spring adjustments with operational tests is 

 repeated automatically and at high speed until the ringer meets its final 

 complete adjustment requirements. This is analogous to the way in which 

 the magnetic circuit and volume efficiency of the individual handset re- 

 ceiver have been automatically adjusted for some time past. 



Fig. 20 — View of nelwork. 



Network 



The network, which comprises the basic telephone set circuit, is also 

 constructed in a form not previously used in this type of apparatus. All 

 components are compactly mounted on a common terminal plate and, 

 after wiring, the assembly is housed and impregnated, Fig. 20. In addition 

 to compactness, this type of assembly provides many other advantages. 

 Wiring is simplified, since the interwiring of components is accompHshed 

 largely without recourse to separate wires, the terminal wires of the com- 

 ponents being used wherever possible. "Bee-Hne" wiring can be employed, 

 since the wires will subsequently be protected by the housing and impreg- 

 nation. The number of terminals required is also reduced. A substantial 

 manufacturing benefit is realized by utilizing common impregnation which 

 obviates the necessity for protective finishes and coatings of the individual 

 components. The assembling and wiring of the telephone set is greatly sim- 

 plified. An added benefit is reaUzed in the field where the mechanical protec- 

 tion provided by the network housing eliminates the possibiUty of damage 

 to the parts in the process of servicing the set. 



