Patent GB-592798-A (GB)
Title: Improvements in or relating to electric impulse producing apparatus
IPC: G06F3/02
Filed: 1944-05-19
Abstract: 592,798. Calculating - apparatus. NATIONAL CASH REGISTER CO. May 19, 1944, No. 9749. Convention date, March 3, 1943. [Class 106 (i)] [Also in Group XL] To produce successive bursts of pulses, each consisting of a selected number, a single electronic pulse generating means is operated under the control of a plurality of normally ineffective preset control means (keyboard), a selector switch rendering the control means effective in succession. After an operation of a keyboard 22, Fig. 1, the start key 217 is operated, causing bank selector switch I, 23 to prepare a selected valve in the pulse generator 20, to be fired by a pulse from recycling means (not shown) which causes a selected valve to fire, generating a pulse and firing the remaining valves up to the terminal valve T. The latter transmits a pulse to the recycling means which in turn causes valve II in the bank selector switch to operate and the second keyboard row to become effective and also transmits a firing pulse to initiate the second train of pulses from the generator 20. The valves in the bank selector switch may be replaced by a sequence switch. Pulse generator and recycling control means, Fig. 2. Gas filled valves 10 ... 1 and a terminal valve T, connected to the cathode of each to the control grid of the succeeding valve are normally held non-conducting due to a high negative potential on the grids: The grid potential of a selected valve 9 is rendered less negative over connection 197 with the result that a pulse subsequently applied to terminal 383 from the control means, Fig. 4, is effective to cause valve 9 to fire, subsequent valves firing down to the terminal valve T, each valve being extinguished by the succeeding valve due to the common anode resistance 104 and the individual cathode condensers 70. The firing of valve T causes the cathode potential to rise, thus extinguishing the normally conducting valve 166, the valve re-firing as the cathode potential falls to extinguish the valve T over the coupling condenser 183, the negative pulses from valves 10 ... T inverted in the normally conducting pentode 110 are applied to pentode 111 biassed beyond cut off to produce a sharpened negative pulse at terminal 112. When valve 166 re-fires, the fall in anode potential is applied to the grid of a normally conducting valve 272 to produce a positive pulse at the anode which is fed over terminal 295 to the re-cycling control means, Fig. 4, to fire valve 274, the resulting positive pulse on the cathode being fed over terminal 339 to the keyboard. After a delay due to condensers 344 and 346, valve 274 fires followed by 276, each extinguishing the previously conducting valve in the same manner as in the pulse generator. The positive pulse on the cathode of valve 276 is sharpened by valves 277, 278 the output being fed over terminal 383 to fire the selected valve in the pulse generator to generate the next burst of pulses. Keyboard and selector switch. Gas-filled valves I ... V, Fig. 3, are normally held non- conducting due to the large negative grid potential, the operation of the selected key 9 connecting the cathode of valve I to the grid circuit of valve 9 over terminal 197 and disconnecting the grid circuit of the terminal valve T. Rectifiers 262 prevent interaction of one row with another if the corresponding key or no key is depressed in two banks, the valves being arranged to fire and extinguish in a similar manner to the pulse generator. Operation. Upon closing the start key 217, Fig. 5, relay 386 operates and locks over its own contacts, applying suitable potential to the circuits connected to terminals 100, 200 and later to 400, valve 166, Fig. 2, firing before the circuit of Fig. 4 is energized so that the pulse is ineffective in firing valve 274. The application of negative potential to terminal 300 is also delayed, with the result that valve I fires, the rise in cathode potential preparing the appropriate valve of the pulse generator. The application, of a positive potential to the valve 404 causes the anode and grid potential to rise after a delay due to the condenser connected between the grid and earth, the pulse generated by the valve firing being fed over terminal 428 to fire valve 276, resulting in a pulse being emitted over terminal 383 causing the selected valve in the pulse generator, Fig. 2, to fire and a burst of pulses to be emitted. When terminal valve T extinguishes, resulting in a triggering pulse from the anode of valve 166, valve 274 is fired and supplies a pulse to the bank selector switch over terminal 339 to cause the valve II to fire and extinguish valve I, preparing the grid circuit of the valve selected in the second row. After a delay, valves 275, 276 fire to produce the pulse which fires the selected valve in the pulse generator. This process continues until valve 216 is fired after the last train of pulses has been emitted causing the stop valve 405 to fire over the connection 452, to operate relay 396 thereby opening the locking circuit of relay 386 which falls away.