DYNAMIC MEASUREMENTS ON ELECTROMAGNETIC DEVICES 1433 



The differentiated output appears as a positive voltage impulse across 

 the cathode resistor of a coupling tube, impressed on top of its normal 

 dc bias due to current from the following quinary ring. The coupling 

 circuit has the appearance of a cathode follower, but except during the 

 short intervals of impulse transmission, the plate does not conduct. 

 This lends itself to supplementary use of the rings as counter circuits. 

 An on-off gate can be connected, as shown, to enable or disable the grid 

 bias of this tube, without introducing any false starting or stopping 

 counts. 



Quinary-Binary Counters. The unit decade counter is shown in Fig. 13. 

 It is a modification of Weissman's quinary-binary circuit* and was chosen 

 because it provides simple two wire selection for the coincidence circuits. 

 The principal modification consists of applying the shift pulses to the 

 odd cathode lead rather than to a grid multiple, and using a direct 

 coupled positive impulse for shifting. 



The shaded tubes are non-conducting at time and can be set in this 

 condition by momentarily opening and then closing the reset key. The 

 plate current from the right half of the zero tube passes through the 

 cathode resistor of the output tube in the pulse shaper described above, 

 and biases both tubes, the latter beyond cutoff. The plate currents from 

 the other four tubes pass through the second cathode resistor having 

 3^ the resistance, developing the same bias. 



A positive cathode impulse applied by the pulse shaper shifts the (0) 

 tube from right to left half conduction. In shifting, the negative pulse 

 from the prior non-conducting half of the zero tube cuts off the conduct- 

 ing half of the (1) tube, causing it also to shift. The shift of the (1) tube 

 puts an aiding backward pulse into the (0) tube and a fonvard pulse 

 into the (2) tube to keep it unchanged. Successive cathode impulses 

 continue the ring stepping, the ring closing on itself after the fifth count. 

 Thus the ability to shift properly depends solely upon the impulse wave- 

 form from the pulse shaper, which can be controlled independently of 

 the ring circuit. 



At the beginning of the fifth impulse, a square negative impulse is 

 passed by the conducting half of the twin coupling diode to the (5) binary 

 tube, causing it to shift. On the next round, the other half of the diode 

 conducts, restoring the (5) tube. The twin diode behaves as an infinite 

 capacitance in a circuit having zero time constant. 



For each of ten successive impulses there is a different configuration 

 of conducting tubes, and two wires, one to the quinary ring and the other 

 to the binary tube, can identify when a selected state is reached by a 

 coincidence circuit noting that a low voltage is present on each wire. 



