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BELL SYSTEM TECHNICAL JOURNAL 



feed-back ratio may be made arbitrarily great and the angle arbitrarily 

 small without the condition being unstable. This agrees with the 

 expression just obtained, which shows that the only effect of increasing 

 the gain is to increase the frequency of the resulting transient. 



5. Let the conditions be as in 1 and 3 except for the fact that four 

 separated condensers are used. Then 



yl/M 



B' 



(a + ico)'* 



(52) 



The solution is most readily obtained by selecting every fourth 

 term in the series obtained in 1. 



s{t) = Be-"\BH'/3l + B't'/ll + 

 = f5c-«' (sinh Bt - sin Bt), 



■) 



(53) 



This indicates a condition of instability when B — a, agreeing with the 

 result deducible from the admittance diagram. 



6. Let the conditions be as in 5 except that there is a reversal. 

 Then 



Y = 



- B' 



(a + •z'co)'* 



(54) 



The solution is most readily obtained by changing the sign of every 

 other term in the series obtained in 5. 



s(l) = Be-"\- BH'/Sl + B'tyjl - • • •)• 



(55) 



w- plane: 



Fig. 6 — Illustrating Example 6, with two values for B. 



