Patent GB-761123-A (GB)
Title: Improvements in or relating to an electronic counter
IPC: H03K23/82
Filed: 1952-10-03
Abstract: 761,123. Electronic counting apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. Oct. 3, 1952 [Dec. 21, 1951], No. 24810/52. Class 106 (1). ). [Also in Group XL (c)] An electronic counter includes binary counting stages, each having a conductive and a non-conductive section, or free-running multivibrator, coupled to a source of pulses to be counted whereby each pulse is applied simultaneously to each stage or multivibrator, and coincidence circuit means interconnecting the stages or multivibrators so as to switch them in the binary notation in response to the pulses. The -16 frequency divider or counter shown in Fig. 3 consists of binary stages UT1, UT2, UT4, UT8, each comprising cathode follower output tubes CF50, CF52 and a multivibrator having cross-coupled triodes 10L, 10R to which negative pulses are supplied, at time intervals less than the natural period of response of the multivibrator, from a gate tube KT having positive pulses applied to its control grid at 1Ás intervals from a source 61. A gate tube is responsive to the applied pulses when a relatively positive potential is applied via terminal Sg to its suppressor grid. Such potential is only applied if all the preceding stages are in the condition with tube 10L conductive and terminal CFL positive; thus terminal Sg of UT2 is connected directly to terminal CFL of UT1, and the terminals Sg of UT4 and UT8 are connected to all the preceding terminals CFL through a series of coincidence gates comprising rectifiers 70a, 70b, 72a, 72b, an operative (earth) potential being applied constantly to Sg of UT1. A further gate comprising rectifiers 74a, 74b supplies output pulses through cathode follower CFO-U to terminal UC. The stages may be replaced by bistable trigger circuits, e.g. of the Eccles-Jordan type (Fig. 1, not shown), to form a binary counter capable of responding to random pulses. Fig. 2 shows another form of bistable trigger in which the multivibrator 10L, 10R is controlled by a clamping circuit comprising tubes 35, 36. When,. e.g. tube 10L is conductive its control grid is held at a high potential through resistor 55 connected to + 150v., while the low anode potential due to conduction through tube 36 is applied to the grid of tube 10R to maintain it non-conductive. When the conductive conditions of 10L, 10R are reversed by a trigger pulse from tube KT, pulses are applied from cathode followers CF50, CF52 to the control grids and cathodes of tubes 35, 36 to reverse the conductive condition of these tubes also. In a decade counter comprising four such trigger stages T1, T2, T3, T4, Fig. 4, the terminals Sg of T2, T3, T4 are controlled from the terminals CFL of preceding stages, and also from terminal CFR of T4, through series connected coincidence gates comprising rectifiers 97, 98, 101, 102 and 105, 106. Terminal Sg of T4 is controlled also from cathode follower CFO-D, the two controls, over lead 93 and from gate 105, 106 being applied to the control grids of a double triode cathode follower 84 forming an " or " gate. The output coincidence gate con. nected to CFO-D comprises rectifiers 108, 109 controlled from terminals CFL of T1, T4. Starting with all stages in the " Right condition " (CFR positive), the counter operates in normal binary fashion for the first nine pulses received from source 61. Stages T1, T4, are then both in the " Left condition," gate 108, 109 is operative and gate 97, 98 is closed, so that the tenth pulse will trigger T1 and T4 (not T2) and return the counter to the starting condition.