GB737455A - Improvements relating to apparatus for examining recurrent electrical waveforms - Google Patents

Abstract

737,455. Instantaneous voltage measurement; cathode-ray oscilloscopes. METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. Sept. 9, 1952 [Sept. 10, 1951], No. 21297/51. Class 37. [Also in Group XL (c)] In a system for measuring the amplitude of a selected point on a recurrent electrical waveform, the waveform is applied through a switch S to the suppressor grid of a pentode valve V and positive gating pulses synchronized with the waveform are applied via a variable delay device to the control grid, the gated output being applied through a pulse lengthener to the Y plate of a cathode-ray oscilloscope. An amplitude calibration trace is produced by operating switch S to apply to the suppressor grid of V an adjustable voltage from a calibrated potentiometer R3 which is in series with a reference voltage from a source " D.C. Level " coupled to the D.C. supply to valve V via a cathode follower. The calibration trace is aligned with the signal trace by adjusting potentiometer R3, the quantity indicated thereby being the difference between the amplitudes of the reference voltage and the gated portion of the waveform. The delay may be varied continuously or in steps and the switch S is operated cyclically at a rate less than the recurrence frequency of the waveform ; alternatively if a long-afterglow tube is employed the switch may be operated manually.