COUNTERS 



very negative and in consequence the glow moves there, only to be auto- 

 transferred to the « + 1th cathode. 



It might seem at first sight that the first and third guides might be dis- 

 pensed with ; that the leading edge of the transfer pulse could be used to 

 move the glow from nth cathode to a guide, and the trailing edge would 

 then move it on the « + 1th cathode. The difficulty is to prevent its moving 

 back to the nth again. In point of fact single-guide tubes do exist; specially 

 shaped electrodes ensure that transfer occurs in the required direction. 



♦ 300 __ — +A75V 



330pF 



"L-T 1M 

 UO V 



drive pulse, not 

 less than 25 psec 

 long 



Carry 



20 V 



Figure 41 .19 



A GC 10 D can be driven from another GC 10 D via a GTE 175 M high- 

 speed trigger tetrode at rates up to 1,000/sec. The necessary circuit is 

 shown in Figure 41.20, and is reproduced from part of reference 4 in this 

 chapter. 



+ 300 



'130 k 



330 k 



From 

 output 

 cathode 

 of __^_ 



GTE175M 



previous 

 GCIOD 



IM 



w 



•150k 



330pF 



To circuit of 

 ■*" Figure AM9 



370pF 



lOM 



-100V 

 Figure 41.20 



A scaler for radioactivity measurements using dekatron counters has 

 been described by Florida and Williamson^^. Kerkut^^ has given details 

 of a dekatron action-potential counter. The time marker, employing 

 dekatrons, published by Kay has already been mentioned. 



653 



