1152 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1956 



■300 



COMPARISON 

 CIRCUIT 



MASTER FILM 

 SPROCKET 



0= f (t) 



20 RPM 

 (NOM.) 



NOM. SPEED 

 3600 RPM 



I MEG 



600 RPM 

 (NOM.) 



600 RPM 

 (NOM.) 



IMF 



-|Vj^ -NN^ +250 

 )l r 1 VI 



I MEG 



Fig. 10 — Block diagram of film scale calibrator with schematic of comparison 

 circuit. 



