Patent GB-682220-A (GB)
Title: Electrical impulse generator
IPC: H03K21/08
Filed: 1950-12-11
Abstract: 682,220. Digital electric calculating-apparatus. NATIONAL CASH REGISTER CO. Dec. 11, 1950 [Dec. 17, 1949], No. 30199/50. Class 106 (i). [Also in Group XL (c)] Apparatus, especially for use with an electronic accumulator, for generating bursts of selected numbers of electrical impulses comprises a plurality of impulse-generating electron tubes to which driving impulses are applied and a gas-filled control electron tube connected to each impulse-generating tube so that the latter is operative to respond to driving impulses when its associated control tube is conducting, the control tubes being rendered conducting one after another by successive driving impulses. A " start " gas-filled tetrode 450 is fired by the closing of a switch 88 which causes a positive pulse to be applied over a condenser 86 to the control grid. The cathode of the " start " tube 450 is coupled to the control grid of the first of nine gas-filled tetrodes (only two of which are shown), which tube 750 corresponds with the digit 9 and is consequently primed. The auxiliary grid of each of the nine gas-filled tetrodes is coupled by a line 73 to the cathode of a triode 32, to the grid of which positive pulses are applied from the anode of one, 12, of the triodes 11, 12, of a multivibrator circuit. Positive pulses are thus continuously applied to all of the auxiliary grids of the nine gas-filled tetrodes. When the " 9 " tube is primed, the following pulse on its auxiliary grid will fire it. As its cathode is coupled to the control grid of the " 8 " tube, that tube will be fired by the next pulse and so on. Associated with each gasfilled tetrode, e.g. 750, is a gate triode, e.g. 100, the grid of the latter being coupled to the cathode of the former. Thus, while a tetrode is conducting, the associated triode gate is opened and positive pulses from the tube 32, applied over a line 114 and a condenser 113 to the grid of the gate triode, produce positive pulses at the cathode which is connected to a line 120. The cathode of the " 1 " gate triode (Fig. 1B, not shown) is connected by a line 145 to an extinguishing circuit. When the " 1 " gate triode produces its positive pulse, a corresponding, but longer pulse, is applied by a condenser-diode circuit 182, 177 to one of the grids of a double triode 161. The other grid is connected to an adjustable potentiometer and the anodes are connected together over a resistor 160 to the high-tension supply and directly to the control grid of a tetrode 48. The pulse applied to the double triode lowers its anode potential and consequently the grid potential of the tetrode 48. The cathode potential of the tetrode 48 is thus lowered to an extent sufficient to extinguish all of the gas-filled tetrodes, the anodes of which are connected thereto by a line 46. Since the gas-filled tetrodes are fired in sequence, the gate triodes produce from 9 pulses down to 1 pulse, respectively. Each order of the accumulator is connected by a line, e.g. 122, and a selected key-operated switch, e.g. 121, to the gate triode corresponding with the particular digit to be entered in that order. The " O " switches are connected over a resistance to the cathode supply line for the gate triodes. The anode-cathode circuit of each gate triode is of low impedance so that strong impulses are produced which are capable of simultaneous application to several denominations of an accumulator. The anode of the second triode 11 of the multivibrator is coupled through a triode 190 to produce negative pulses on a line 200 between the positive pulses produced by the gate triodes in order to effect transfers in the accumulator, which may be as described in Specification 682,221.