332 



ISOTOPIC TRACERS AND NUCLEAR RADIATIONS [Chap. 10 



V2 REGISTER 



OB+ 



Fig. 86. Multivibrator recording circuit. 

 221 = 1 megohm 

 R2 = 100,000 ohms 



223 = 50,000 ohms 



224 = 500,000 ohms 

 226 = 5,000 ohms 



Approximate values of circuit constants are 

 CI = 0.0001 /ifd 

 C2 = 0.001 /ifd 

 VI = 6SJ7, 6C6 

 F2 = 6V6, 6F6 



O— f 



C2 



R4 



n 



-=- O O ~^" o 



B+ I B+ 



Fig. 87. Thyratron recording circuit. Two arrangements of the register circuit are illus- 

 trated to the right of the broken lines. Circuit I is preferred since the recorder is at ground 

 potential and there is less chance of damage to the register due to surges. Approximate 

 circuit values are 



221, R3 = 500,000 ohms CI = 0.001 M fd 



R2 = 100,000 ohms C2 = 1 - 4 /*fd 



224 = 200,000 ohms VI = 6C5 



225 = 10,000 ohms V2 = Thyratron; e.g., 884 



cuit from one state to the other; hence two input pulses of the same sign 

 are required for a complete cycle. Although two output pulses also appear 

 per cycle, they are opposite in polarity and one pulse can be rejected by a 

 "clipping" circuit immediately following each of the trigger circuits. Nor- 

 mally, the negative pulse, which is the first output pulse in the cycle is 



