Patent GB-592407-A (GB)
Title: Improvements in or relating to electric impulse producing apparatus
IPC: H03K3/78
Filed: 1944-05-19
Abstract: 592,407. Impulse generators. NATIONAL CASH REGISTER CO. May 19, 1944, No. 9735. Convention date, Nov. 7, 1940. [Class 40 (v)] Apparatus for the high-speed production of a selected number of electrical impulses, comprises a plurality of diode gas discharge tubes connected anode-to-cathode in series so as to discharge automatically in succession starting at either end of the series on operation of a starting device, control means for terminating the sequential discharge at any selected tube in the series and an output conductor coupled to the tubes so as to receive an impulse from each tube as it discharges. In order to produce two electrical impulses in the .output conductor 9 and 10, the "2" key 12 and starting key 13 are operated. Operation of key 12 connects the 500 volt supply line 14 to conductor 15 and disconnects the anode of tube III which is next in the chain from the conductor 15 so that all the tubes except III are supplied with an anode-cathode potential slightly smaller than that necessary to cause them to become conducting. When the start key 13 is operated, the anode and cathode of tube S tend to rise to 500 volts, but as condensers 3 and 24 charge, the anode 16 drops to the potential of point 39 determined by the values of resistances 20, 41 and 36 and the cathode 31 to zero, so that the tube fires when the anode-cathode potential reaches a certain value. The potential of anode 16 drops when tube S starts conducting, causing a proportionate drop at cathode 32 of tube I, so that the anode-cathode potential becomes sufficient to cause tube I to fire. The potential of anode 17 will tend to drop when tube I begins conducting, but is prevented from doing so by condenser 53, which was charged when key 13 was closed, so that the cathode voltage rises momentarily and then both drop as the condenser discharges. This rise in cathode potential causes a positive impulse on output conductor 10, and the drop of anode potential causes a negative impulse on conductor 9. The cathode potential of the following tube II will be reduced so that it in turn fires and produces a second positive and negative impulse on conductors 10 and 9 respectively. The tube III will not fire since its anode is disconnected from the supply voltage. The complement to the number of the key depressed may be obtained by operating the tubes I, II, III in the reverse order by depressing key 8 to disconnect anode 16 from cathode 32, connect cathode 31 to anode 19 through resistance 76, and connect condensers 35 and 24 to ground. The anode and cathode of tube S will be momentarily grounded when the key 13 is operated, but as the condensers charge, the anode will rise towards 500 volts and the cathode to a voltage determined by the value of resistances 25, 76 and 23, thus causing the tube to fire. The cathode potential will immediately rise causing a proportionate rise at anode 19 of tube III which will fire. Condenser 67 then discharges to give positive and negative impulses on conductors 10 and 9 as before and the rise of cathode potential produced causes the preceding tube II to fire, and so on.