IMPROVED CIRCUIT FOR TELEPHONE SET 



613 



100 



60 

 40 



20 



10 



6 



to 



•3 4 



o 



> 



u 



Q 2 



1.0 



0.6 

 0.4 



0.2 



0.04 



10^ 



z 



2 ^ 



(/I 



10 



0.1 



0.2 



20 



0.4 I 2 4 6 10 



DC CURRENT IN MILLIAMPERES 



Fig. 1 — Characteristics of Vi and V2 varistors. 



40 60 100 



observed that the resistance decreases markedly with increasing volt- 

 age or current. 



The direct current characteristics of a siHcon carbide varistor may be 

 expressed in a simple form by 



7 = AE^, 



(1) 



where 7 is the direct current through the varistor and E is the applied 

 dc voltage. When n = 1 the equation (1) reduces to an ohm's law 

 relationship. A and n are generally regarded as constants when considered 

 over a limited range in current. However, over the range shown in Fig. 

 1, it may be seen from the curvature of the voltage — current char- 



