GB688599A - Improvements in or relating to arrangements for indicating the variations of electrical or other physical quantities - Google Patents

Abstract

688,599. Electric indicating systems. STANDARD TELEPHONES & CABLES, Ltd. June 15, 1951, No. 14243/51. Class 40 (i) [Also in Groups XIX and XXXVI] An arrangement for indicating the variations of an electric or other physical quantity comprises electric trigger devices and counters controlled thereby, corresponding respectively to selected discrete values of the quantity, and means for periodically " inspecting " the value of the quantity, such means being adapted to cause operation of that counter corresponding to the highest selected value reached by the quantity at the moment of inspection. In the arrangement shown in Fig. 1, for indicating the variations in signal level at a station of an electric communication system, five cold cathode gas-filled trigger tubes 1-5, each corresponding to a selected signal level, control counting devices 6-10. The anode current of one or more variable gain amplifier stages such as 39 is passed to the moving coil 28 of a current-measuring device 20 whose pointer 21 is thereby located over a strip 22 and one of five strips 23-27 corresponding to tubes 1-5 respectively. When the portion 47 of a constantly rotating cam 36 closes a switch 12, H.T. voltage is applied to the tubes and, on the subsequent closure of switch 34, a capacitor 33 discharges through the primary of a transformer 35 thus causing sparks to pass from 22 to 21 and from 21 to 24 (as shown) so that a firing pulse is applied to the trigger electrode of tube 2 thus stepping on counter 7. Also, if the tubes are coupled by transformers 16-19 as shown, all the tubes to the right will also be fired, so that each counter will register the number of times a given signal level has been exceeded or not exceeded according to whether the needle 21 moves to the left or right for increasing signal levels. In a modified arrangement, operated by the amplifier gain control voltage applied through a reversing voltage-stabilized tetrode to a potential divider, successive adjustable tapping points are connected to the trigger electrodes of the tubes so that all those tubes to which a voltage of not less than the critical value is applied will be fired. The device 20 of Fig. 1 could be replaced e.g. by a pressure gauge, a water level indicator or a wattmeter.