Patent GB-669962-A (GB)
Title: Improvements in or relating to electronic counters
IPC: H03K23/82
Filed: 1949-11-22
Abstract: 669,962. Electron counting apparatus. BRITISH TABULATING MACHINE CO., Ltd. Nov. 22, 1949 [Dec. 11, 1948], No. 29881/49. Class 106 (i). In a high-speed decimal electronic counter having four series-connected trigger circuits A, B, C, D, each having two grid-controlled tubes alternately conductive in response to pulses received, and an isolating tube V1T operatively connected between triggers A and B, the plate circuit of tube V1T is connected to a tube D1 of trigger D, and a blocking tube BLT, connected to trigger B, renders it non- responsive to tube V1T during part of the counting cycle. The counter shown is in the zero or starting condition, obtained by opening switch CBS, the right-hand trigger tubes A2- D2 being conductive (Indicated by dots). Three isolating tubes V1T-V3T have their control grids connected to the plate circuits of trigger tubes A1, B1, C1 respectively, so that when these trigger tubes become non- conductive positive pulses are applied to the isolating tubes to cause them to conduct and produce negative pulses in their plate circuits. Tube V2T does not remain conductive since it has only a capacitative connection 42 with tube B1. Negative pulses to be counted are sent from terminal 38 to the plates of trigger circuit A which is thus switched alternately to each of its two stable conditions. When two pulses have been received, trigger A is switched to the condition shown and a negative pulse is sent from the plate of tube V1T to similarly switch over trigger B. A fourth pulse switches back trigger B whereupon a momentary pulse is sent from the plate of tube V2T through decoupling rectifiers 62, 63 to the control grids of tubes C1, C2, thus switching over trigger C. An eighth pulse switches back trigger C and a negative pulse from tube V3T is sent over lead 75 to the control grid of tube D2 to switch over trigger D. A negative pulse from the plate of tube D1 is then sent through lead 92 and rectifier 93 to the control grid of a tube T2 of a blocking trigger circuit T. The trigger T is thus switched to the condition shown and the increased voltage at the plate of non-conducting tube T2 is sent over lead 98 to the control grid of blocking tube BLT which then conducts and, through connection 104 between its plate and the control grid of tube B1, prevents the switching of trigger B from the condition shown. The increased voltage at the plate of non-conducting tube D2 is applied over lead 77 to the control grid of a switching tube S1T which then conducts thus lowering the plate voltage of tube S1T and a further tube S2T. Upon the receipt of a ninth pulse (and every other odd-numbered pulse), tube V1T becomes non-conductive and a positive pulse is sent from its plate circuit over line 89 and through condenser 88 to the control grid of tube S2T, but this has no effect due to the low plate voltage. A tenth pulse causes tube V1T to conduct again, but the negative pulse at its plate is prevented from affecting trigger B and, instead, is sent over line 47 to the control grid of tube D1, thus switching trigger D back to the position shown. The decreased plate voltage of tube D2 cuts off tube S1T, and may also be used to indicate that the count of ten is completed. On receipt of the first pulse of the next counting cycle, a positive pulse is again sent over line 89 to tube S2T which then conducts and the decreased plate voltage is applied over line 91 to the control grid of tube T1, thus switching over trigger T and cutting off the blocking tube BLT so that trigger B can respond to the second pulse.