GB846558A - Improvements in trigger circuits and counters including such circuits - Google Patents

Abstract

846,558. Bistable state circuits. INTERNATIONAL BUSINESS MACHINES CORPORATION. Jan. 8, 1957 [Jan. 10, 1956], No. 748/57. Class 40(6). [Also in Group XIX] A bi-stable trigger circuit comprises a single gas filled discharge tube having a first input circuit connected to a trigger electrode and a second to its cathode. The second circuit delays pulses supplied to it so that a pulse simultaneously applied to both circuits is not effective at the cathode until it has ceased to be effective at the trigger electrode. In this way a train of pulses applied to the input circuit causes the tube to be successively fired and extinguished. Fig. 1 shows a bi-stable trigger circuit comprising a thyratron, input trigger impulses being applied at terminal 5. If it is assumed that initially the thyratron is conducting capacitor 7 is charged so that the first positive input pulse applied to the trigger electrode is ineffective but raises the potential of the cathode to extinguish the tube. The next input pulse at 5 is ineffective at the cathode but causes the tube to be refired. Capacitors 6, 7 and their associated resistors have values such that a pulse arrives at point 8 without marked deformation whilst the derivative of the pulse arrives at point 9. The voltage excursions at the cathode, (Fig. 1a not shown), may be used to trigger a further similar stage. In a modification shown in Fig. 2 the first input pulse from terminal 5 when the thyratron is conducting is applied through neon tube or biased diode 12 to the cathode to extinguish the tube the succeeding positive pulse at the input fires the tube and the cycle is repeated. Capacitors 2 and 11 have a value such as to delay cathode negative feed-back. A third input terminal may be provided connected via a neon tube 13 to the trigger electrode. If a delayed pulse is applied to this input terminal and a pulse to the other terminal the thyratron is extinguished but immediately fired again. Separate input connections to the striking electrode and cathode may be used or a common input connection. A cascade of such bi-stable trigger circuit with feed-back connections between them enables counts on scale of 2, 10 or 12 to be obtained Figs. 3, 4, 5, 6 and 7 not shown (see Group XIX.)