IMPROVED CIRCUIT FOR TELEPHONE SET 



621 



Fig. 7 - 125A Network used with early design of sut the oUUA and li typo. 



the Vi and V2 varistors have been included in the network (425B), 

 thereby providing mechanical protection for these elements. It has been 

 necessary to design a new terminal block which is the plastic member to 

 which the components of the network are mounted. 



OVERALL RESULTS 



By means of the Vi and V2 silicon carbide varistors and the rearrange- 

 ments made in the circuit, the overall transmission performance of the 

 modified set has been made substantially the same as that provided by 

 the original design of set. The savings in manufacturing cost resulting 

 from this modification are significant. Figure 9 shows on the left the 



Fig. 8 — ■ 425B Network used in present production set — the 500C and D type, 

 showing the Vi and V2 varistors. 



