TRANSISTOR OSCILLATOR FOR MULTIFREQUENCY iHiLSlNG 1331 



Appendix II 



The equivalent circuit for the oscillator is shown in Fig. 14. For stable 

 operation from equation (1), since /o = 1/^, 



1 _ g- 2L = g- 2L _ 1^ 



The negative resistance, { — R), must therefore be equal to the positive 

 resistance (-{-R). If however { — R) is active for only half the time, 

 {—R) must be equal in magnitude to 2(+/2) in order to satisfy the 

 requirements for equality. This assumes that boundary effects are 

 negligible. This assumption was borne out by experiment. 

 The equivalent resistance of the resonant circuit is 



,..{^Jn.K'- 



R 



where 



k = (cooL)2. 



A plot of this relationship when positive and negative resistances are 

 combined, is shown in Fig. 15. 



In the actual circuit the negative resistance is connected across the 

 1-2 winding. The 1-3 winding is in the resonant circuit. The equivalent 

 resistance (i?o(i-2) of the resonant circuit across mnding 1-2, is de- 

 termined as follows : 



_ (turns, winding 1-2)^ ^ 

 ^'''■'' - (turns, winding 1-3)^ ^ ^^' ' 



