Improvements in electrical pulse arrangements

985,431. Automatic exchange systems; circuits employing bi-stable magnetic elements. STANDARD TELEPHONES & CABLES Ltd. April 6, 1962 [April 7, 1961], No. 12624/61. Headings H3B and H4K. Metering pulses are stored in magnetic cores each individual to a subscriber, the individual core switching conductors LINE 000 to LINE 999 from the subscribers' private wires being connected over rectifiers to a common electronic switch ES closed for short periods only in recurring cycles so as to prevent spurious switching pulses from being registered. The switch ES has for example an open time of 105 m.s. and a closed time of 10 Ás., the closed period being just sufficient to ensure switching of a core by a metering pulse. With these switching times, a metering pulse period of about 200 m.s. and an effective length of a spurious pulse of about 30 Ás., the probability of faulty core switching is reduced to the order of approximately 1 in 4000. Rows of cores are read out in turn from a scanning access selector AS at a rate higher than the possible arrival rate of metering pulses, and outputs are obtained in column conductors CT. Specification 902,401 is referred to.