106G THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1956 



tribiition of noise the resultant phase shift of the timing wave will be 

 negligible. If the interference has low frequency components, the phase 

 shift of the timing wave may be appreciable but these are slow and con- 

 sequently will not seriously effect the performance of the regenerator. 



2.0 DESCRIPTION OF REPEATER CIRCUIT 



The circuit diagram shown on Fig. 3 will aid in understanding the op- 

 eration of the repeater. The incoming signal after being transmitted over 

 the equalized line is applied through the input transformer Ti to the 

 emitter of transistor (1). The function of this transistor is to provide gain 

 to the incoming signal. This amplified signal is applied to the emitter 

 of transistor (2) through the blocking condenser C2 . The second transis- 

 tor functions in a single shot blocking oscillator circuit being biased in the 

 "off" condition through the resistance i?2 . When the positive signal ex- 

 ceeds the trigger threshold, a pulse is regenerated by the blocking oscil- 

 lator. During the pulse period a large emitter current flows through Di 

 in the conducting direction. T^ is the output transformer while trans- 

 former T3 provides the essential positive feedback for the blocking oscilla- 

 tor. 



L, R, 



-'TW VW 



N 



BOOTSTRAP TIMING 

 TUNED TO 672 K.C 



INPUT 



QUANTIZED FEEDBACK 



AAA- 



Fig. 3 — Circuit diagram of the regenerative repeater. 



