Electronic recording device known as a momentary memento

摘要

744,161. Pulse memory circuits. MULLARD RADIO VALVE CO., Ltd. March 6, 1952 [March 6, 1951], No. 5472/51. Class 40 (6). In a memory device for repetitive phenomena an alternating potential is applied to one plate of a capacitor, the other plate being held at a reference potential by a clamping circuit until the clamp is released by a signal derived from an input pulse, the capacitor retaining its charge until a corresponding potential is reached during the next working stroke of the alternating potential. The alternating potential may be a negative going sawtooth, Fig. 3 (a) fed from time-base 2, Fig. 1, to a capacitor 1 having its right side held at earth by tubes V1, V2 conducting so that the capacitor charges negatively during the working stroke. The recurring phenomenon produces a pulse, Fig. 3 (b), which is converted by trigger pair 9 into a negative step, Fig. 3 (c), which cuts off the tube V1, V2 to remove the clamp. The potential of lead 4, Fig. 3 (d), now falls with the sawtooth input to the end of the working stroke 1 and on rising during the return stroke cause normally cut-off tube V3 to conduct to reverse the state of pair V3, V4. During the next working stroke, if potentiometer 8 is correctly adjusted, the potential of lead 4 falls sufficiently for the pair V3, V4 to restore. The fall in anode potential causes the trigger pair 9 to restore thereby re-operating the clamp, Fig. 3 (c), (d), so that lead 4 is again held at earth.- The next pulse opens the clamp to reset the charge in the capacitor 1. The negative-going waveform at the anode of tube V4 may be employed to operate an indicator. The device may be employed in systems where a phenomenon occurs at approximately the same time during an interval, although the intervals are not necessarily regularly spaced. Specification 727,134, [Group XL (b)], is referred to.