Patent GB-680466-A (GB)
Title: Pulse scaling systems using multi-electrode gas-discharge tubes
Inventor: KANDIAH KATHIRKAMATHAMBY
IPC: H03K29/00
Filed: 1950-01-25
Abstract: 680,466. Pulse circuits. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Jan. 23, 1951 [Jan. 25, 1950], No. 1950/50. Class 40 (vi). In a multi-stage scaler or divider employing multi-electrode gas-discharge tubes of the type having a plurality of stable discharge paths which can be set up in an endless sequence by the application of pulses to each of two or three electrode groups in turn, a pulse generator supplies transfer pulses to a first multi-electrode tube and one or more succeeding tubes each derive transfer pulses from the preceding tubes. Fig. 1 shows in schematic form a scaler or decade divider comprising three gas tubes 2, 9, 10, each having an anode ring 3, a primary cathode electrode group Kl, first and second electrode groups K2 and K3 respectively and a single cathode output electrode element K0. Incoming pulses at lead 5 are applied to the pulse generator 4 which produces two negativegoing output pulses delayed with respect to one another by a time which is insufficient to allow the tube 2 to de-ionise. If a glow discharge exists initially between the anode and the first cathode element of ring K1, then the first transfer pulse on lead 6 will step it on clockwise (as shown) to the first element of the electrode group K2 and the delayed pulse on lead 7 will step it further to the first element of the second electrode group K3. The tenth incoming pulse yields pulses from generator 4 which brings the discharge back to its initial position on element K0 and an output pulse is produced across resistor R. The delayed pulse on lead 7 is applied via lead 11 as a first transfer pulse to tube 9 and the pulse produced across resistor R is amplified in unit 8 and applied as second transfer pulse to tube 9. Similarly pulses from tube 9 are applied as first and second transfer pulses to tube 10. Fig. 2 shows the details of the pulse generating, delaying and amplifying circuits of a scaler in which the tubes V3, V5 and V7 are shown schematically. Positive-going input pulses at 20 fire coldcathode gas tube V1 to produce a negative pulse at its anode which is applied to electrode group K2 of tube V3 to move the discharge one step. The pulse is of short duration as the voltage across capacitor C1 rapidly falls below the maintaining potential and tube V1 is extinguished. The voltage across capacitor C1 then rises with a time constant dependent upon the constants of network R1, R2, C1 until after a predetermined delay tube V2 fires and a negative pulse is applied via capacitor C3 to electrode group K3 of tube V3. Rectifiers Q1 and Q2 limit the positive excursions of the anode voltages of tubes V1 and V2. Every tenth pulse at input 20 gives rise to a pulse across resistor R4 which triggers a further tube V4 to produce a negative pulse at the K3 electrode group of the second scaling tube V5, the transfer pulses to the K2 electrode group of this tube being obtained from the anode of tube V2. Tube V7 similarly obtains transfer pulses from tubes V4 and V6 so that an output pulse is produced across resistor R8 for every 1000 input pulses at 20. The time constant of the coupling network between the output electrode of tubes V3, V5 and the trigger electrodes of tubes V4, V6 respectively is such that the trigger tubes are only on the first positive-going edge of the waveform at the output electrodes. The time constant of the coupling networks between tubes V2, V4 and the K3 electrode groups in tubes V3, V5 respectively is such that the decay of the transfer pulse to these electrodes is hastened, thus advancing the output pulse from these tubes so that the second transfer pulse to succeeding tubes arrives before the first transfer pulse decays.