N 



714 Dr. B. van der Pol on Oscillation Hysteresis in a 



circuits. They are represented in fig. 5 for a constant 

 k 2 = 0'5. Since in (16) a u a 2 and y are independent of o> 2 

 we can trace in the latter diagram the dependence o£ a 2 



and bJ on — and co 2 2 . 



<*2 



For example, if — l is represented by OB the amplitude a 2 

 is by (16) proportional to the vertical distance between the 



Fig. 5. 



B 





w 



\. s 



) 



T 









V 



f 









i 'V 



-^Tu 



-^3T 



i 

 i 

 i 





^^^TqA 







i 

 i 





1 1 ' 

 l-'-l - 



V 





i 

 i 



4- -- 



1 1 







i 



I 

 1 



l 



H G 



t— ~-J .1 — ■ — — 



i • ! 

 i ^ ' 

 1 1 1 

 ap; 



W K 



j. _.L 





I 



I 



.! 



L 



cu; 



(AJ 



line BE and the curve j\{(o 2 ). In a similar way 6 2 is pro- 

 portional to the distance between BE and/n(o> 2 2 )- Thus 

 when &) 2 2 = OH < OG, a 2 is proportional to CD, but when 

 &> 2 2 > OG, ciq 2 would be negative and oscillations of the fre- 

 quency o)j are impossible. In the same way oscillations of 

 the frequency a> n are only possible when co 2 2 > OK. 



If we next consider a larger value of — , e.g. — = 0N, 



