COMPLETE PIECES OF TRANSISTOR APPARATUS 



Transistor R-C oscillators 



A sine wave oscillator of the phase shift type is shown in Figure 45.47. 

 Here again the resemblance to the corresponding valve circuit is clear. 

 RC oscillators of this and other types have been published by Hooper and 

 Jackets^**. 



Figure 45.46 Figure 45.47 



Transistor voltage stabilizers 



The most elementary type of stabilizer is a single transistor connected in 

 what is virtually the earthed collector mode {Figure 45.48). Such a circuit 

 affords a measure of both forward and backward stabilization, and is the 

 transistor analogue of the simple cathode follower arrangement in Figure 

 37.11. The output resistance in earthed collector circuits is usually given 

 with sufficient accuracy by RqI^, where Rq is the signal generator resistance. 



_^ 



Unstabilized 

 supply in 



Stabilized 

 supplyoijt 



X 



Stable 

 reference 

 source 



-o* 



Figure 45.48 



In this case Rq is the resistance of the reference battery, which should be 

 negligible, and we have to use the exact expression which includes the 

 usually unimportant r^, and r^. This is 



^out — ^e + 



h + R 



G 



P 



In a transistor quoted by Evans and CarrolP^ in connection with stabilizers 

 of this type, we have : 



r, = 2-51} 



r, = 150 Q 



r, = 500 kQ. 



1^ = 50 



705 



