Patent GB-592408-A (GB)
Title: Improvements in or relating to calculating or like accumulators comprising electronic devices
IPC: H03K21/08
Filed: 1944-05-19
Abstract: 592,408. Pulse counting circuits. NATIONAL CASH REGISTER CO. May 19, 1944, No. 9740. Convention date, July 17, 1941. [Class 40 (v)] An electronic counter comprises an odd number of high-vacuum electron tubes connected in a ring so as to be rendered conducting one at a time in sequence in response to impulses impressed on all the tubes, a resistance network to which the anodes and grids are connected symmetrically so that only one tube can become conducting at a time, the two adjacent tubes being primed as a tube becomes conducting, and inter-tube connections so that when the conducting tube is extinguished only that one of the two adjacent tubes which follows in the sequence is rendered conducting. As shown, the received impulses are applied to dividing means so that every second impulse is impressed on the ring of electron tubes and the state of the dividing means and the ring of tubes determined. Tubes T1, T2 comprise a dividing trigger circuit so that they conduct alternately on each impulse applied from terminal 20, through amplifier 24 to the grids 40, 41. Amplifier tube 58 will conduct every second impulse due to the rise in potential of anode 49 when tube T2 is non-conducting, and a negative impulse will be applied to the grids of tubes (1)-(5) through conductor 70. Assuming that tube (3) is conducting, its anode will be nearly at ground potential while the anodes of the remaining tubes will be at higher potentials. The grid of tube (3) will be at ground potential and the other grids at negative potentials. A negative impulse on conductor 70 will render tube (3) non-conducting, causing its anode potential to rise and a sharp positive impulse to be applied to condensers 135 and 136. Conduction will not occur through anode 139 and cathode 137 of double diode rectifier 140 and as the positive impulse is attenuated by resistor 138 the grid of tube (2) will not receive a large enough impulse to cause the tube to conduct. A positive impulse, however, will be applied to the grid of tube (4) through the other half of the rectifier, causing it to conduct. The potentials at all points in the resistance. loops connecting the anodes will then change, producing negative impulses at the anodes of tubes (4) and (5) and positive impulses at tube (2) and (3). The negative impulse at the anode of tube (4) is applied through condenser 146 and diode rectifier to the grid of tube (3) to prevent it conducting due to the positive impulse from the anode of tube (2). The next negative impulse will render non-conducting tube (4) and cause tube (5) to conduct. In order to determine the condition of the divider tubes T1, T2 and the ring of tubes, the anode of each of tubes (1) to (5) is connected to the centre point 150 of a resistance network, one side of which is connected through conductor 153 to the anode of tube T1, and the other side through conductor 178 to the anode of tube T2. Connections are made from similar points 154, 156 on the two sides to the contacts 164, 176 of a selector switch. If, on the first impulse, tube T1 and tube (1) are conducting, the contact 164 will be at a lower negative potential than contact 176 and the rest will have positive potentials. On the second impulse, tube T2 will conduct causing the contact 176 to have the lower negative potential. On the third impulse, tube T1 will again become conductive and a negative impulse will be impressed on conductor 70 which will render tube (1) non-conducting and cause tube (2) to conduct, so that the third contact will have a lower negative potential than the fourth contact and all the rest will be positive. When the sensing arm 169 moves over the contact having the lowest negative potential, tube 168 becomes non-conducting and the sensing arm is held and an indication of the number of impulses received given.