458 



BELL SYSTEM TECHNICAL JOURNAL 



gives the conditions for oscillation. Fig. 5 and the relations of (45), 

 (46), (47), (48) and (49) are applicable here. The condition of (54) 

 requires a negative value of rp, and hence is not the usual oscillation 

 condition. The condition of (55) therefore gives the criterion for 



1 

 the oscillation condition. As before, neglecting quantities in ywe 



may write (55) in the following form 



rg-{-qn=() 

 zi{Zg-\-rg 



or 



r,+ 



= 0. 



(56) 



When applied to a hypothetical Hartley oscillator, Fig. 9, with the 

 circuit constants 



F"ig. 9 — Hartley oscillator 



S2 =jc^Lp 



1 _• T 



equation (56) gives as the conditions for oscillation 



1 1 



[ 



LpL^~\ {Lp-\-Lg) C 



Eh -\- Ea 



''J 



(nearly), (57) 



Lt 



[-a]^' 



IxL^ (nearly 



(58) 



