Patent GB-654070-A (GB)
Title: Improvements in or relating to electronic counting arrangements
Inventor: BAKER GEORGE THOMAS
IPC: H04M3/24
Filed: 1947-09-02
Abstract: 654,070. Short time interval measurements. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. Sept. 2, 1947, No. 24174. [Class 37] A short time interval between the occurrence of two events is measured by applying pulses from a standard frequency source to a gating stage which is opened on the occurrence of the first event to let pulses through to a counting circuit and which is closed on occurrence of the second event to stop the counting process. Fig. 1. shows the gate and associated control circuit. Pulses from a standard source which may be derived from a crystal controlled master oscillator by dividing down by a series of multivibrator stages are applied via the pulse amplifier and shaping stage V4 to the gating valve V3 which is normally biassed well beyond cut-off by the trigger pair which is in its normal condition with valve V1 conducting and V2 cut-off. On the occurrence of a first event a negative-going pulse applied to lead 11 or a positive-going pulse applied to lead 10 causes the trigger pair to change over and the bias on valve V3 is reduced to cut-off so that the next positive-going pulse on lead 12 is transmitted through the gate V3 to the counting circuit. On occurrence of the second event a pulse applied to either lead 10 or 11 causes the trigger-pair to revert to its normal position, the gate is closed and the counting action ceases. The counter may comprise a series of scale of ten counters, Fig. 4 (not shown), each comprising four scale of two counters, Fig. 5 (not shown), arranged as shown in Fig. 6, with a connection between the output of the first counter S1 and the input of the last S8 and a connection between the output of the last S8 and the input of the second counter S2. Fig. 7 shows a circuit for a contact timer which is used for the measurement of the time required for the break contact A1 of a relay A to release after the relay has operated, the control pulses produced at leads 10 and 11 controlling the gating circuit of Fig. 1. With switch TS in position 1 the starting key ST is operated thus energizing relay coil A and rendering the diode V23 conductive, the positive pulse at its cathode being amplified by valve V22 to give a negative going starting pulse on lead 10 which changes over the trigger-pair of Fig. 1 as previously described and starts the count. When, after a period, contact A1 opens diode V23 is cutoff and the negative pulse at its cathode appears as a positive going stopping pulse on lead 10 which terminates the counting operation. On other positions of switch TS the circuit may be used to measure the operating time of a make contact, or the difference in operate or release times of two contacts of the same or of different relays, Figs. 8A--H (not shown). A simplified arrangement of the contact timing circuit of Fig. 7, in which less accuracy is obtained is described, Fig. 9 (not shown), and a modification of the circuit particularly suitable for use for timing high-speed relays is described; Fig. 10 (not shown). Fig. 3 shows in block schematic form a circuit for timing the interval between the occurrence of two events in which the counting circuit having once started passes through a complete cycle of operation irrespective of the number of pulses to be delivered. A starting pulse opens gate G1 so that pulses from the standard source I pass to the counter C, when a number of pulses have been counted which is complementary to the number required to be delivered a pulse is fed from the counting circuit to open gate G2 which then passes pulses from source I to a subsequent circuit until the counter has counted out the required number of pulses when a stopping pulse closes both gates G1 and G2. Specification 632,411, [Group XIX], is referred to.