Patent GB-844930-A (GB)
Title: Information translating apparatus
IPC: H03M1/00
Filed: 1956-07-11
Abstract: 844,930. Electronic counting apparatus. GORDON, B. M., and TALAMBIRAS, R. P. July 11, 1956 [July 22, 1955], No. 21495/56. Class 106 (1). [Also in Group XXXVIII] An analogue voltage signal applied at 16, Fig. 1, is compared in detector 10 with the voltage generated by a digital-to-voltage converter 78 which is controlled by the output of a binary counter 55, the output from the comparator 10 serving to adjust the count in the counter to cause the converter voltage to balance the input voltage. The detector 10 compares the input voltage and the converter voltage, which is of opposite sign, by applying them to two series-connected resistors, so that the potential at the junction is the difference. This difference is sampled at a high frequency (100 kcs.) by a detector driver 18, the junction being earthed between samplings by a diode clamp biased to conduct by a signal from the oscillator 20. The sampled value is passed via amplifier 22 to a discriminator 24 which gives a signal on line 28 if the difference is positive and on line 30 if it is negative. These signals vary in magnitude according to the magnitude of the difference and pass to " forward " and " backward " gates 32, 34. Second inputs to these gates are from a blocking oscillator 36 driven through a short delay 38 from oscillator 20. The blocking oscillator merely serves to open the gates 32, 34 so that the signal on line 28 or line 30 is applied to set a flip-flop 46 which controls the counter 55 and gives a signal on add line 54 or subtract line 60. The difference signal from gate 32 or 34 also passes via buffer 62 to blocking oscillator 64. If the difference is greater than a predetermined threshold value an output passes via delay 66 to the " count " line 68. The delay ensures that the add or subtract control in the counter has been set before the counting pulse arrives. The count in the counter is increased or decreased by the pulse on line 68 according to whether the add or subtract line is energized. The outputs from the stages of the counter are applied via a connecting-plug 80 to a digital-to-voltage conveiter 78, the output of which passes on line 82 to the detector 10. The digital equivalent of the input voltage analogue is available on leads 70. The gates 32, 34 are made operative by permissive signals on terminals 40, 42. If one of these is omitted the converter registers the highest or lowest voltage received during a period. When the backward gate 34 is inoperative the counter increases its count whenever the input voltage exceeds the voltage on line 82, but it cannot decrease the count. At the end of any period the counter records the highest value reached. The counter.-The counter consists of a number of bi-stable trigger stages 540, Fig. 4, each consisting of a cross-connected double triode 548. The anodes are connected to the primaries of transformers 562, 582, the secondaries being connected to the control-lines F, B for additive and subtractive counting. Diodes 690, 692 connected to the other ends of the secondaries pass negative pulses to the input capacitor 542 of the next stage. If the control trigger 46, Fig. 1, is set for additive counting a negative voltage is applied to the F terminal and a more positive voltage to the B terminal. When the stage changes from " 1 " to " 0 " a negative voltage from the left-hand transformer 562 produces a pulse which is applied to the next stage to change its state from " 1 " to " 0 " or vice-versa. When the stage changes back from " 0 " to " 1 " the transformer 582 produces a negative pulse but because its secondary is positively biased it is not passed to the next stage. When the B terminal is made negative for subtractive counting, a carry pulse is produced only when a stage changes from " 0 " to " 1." Between stages 4 and 5 there is interposed a pulse-amplifying and shaping network consisting of a triode 710 supplied through condenser 702 and diode 704 and having a transformer 722 in the anode circuit. Triode 710 is normally conducting but is switched off by a negative pulse from stage 4 and this produces a negative signal in the secondary of the transformer, which is applied to stage 5. The tenth stage indicates the sign of the number counted being " 1 " for positive and " 0 " for negative values. A final stage has a neon lamp connected to its " 1 " anode to indicate when the counter counted beyond its capacity.