GB730779A - Apparatus for testing internal combustion engines by means of a cathode-ray oscilloscope - Google Patents

Abstract

730,779. Automatic amplitude control systems. SOCONY-VACUUM OIL CO., Inc. July 1, 1952, No. 16592/52. Class 38 (4). [Also in Groups XXXVI and XL (c)] In. a cathode-ray oscilloscope for displaying signals indicating the performance of an internal-combustion engine and comprising separate horizontal and vertical time base generators synchronized with the engine (see Group XXXVI), the amplitudes of the time bases are automatically maintained constant in spite of variations in the engine speed. As shown, the vertical time base generator comprises a resistor 54 and constant-current pentode 55 in series with a capacitor 49 which is periodically discharged by a thyratron 41 and the horizontal time base generator comprises similar components 84, 85, 76-79 and 74. The negative sawtooth output from the horizontal time base generator is applied via capacitor 95 to the anode and cathode respectively of the left and right-hand sections of a double diode 92 and the cathode of the left-hand section is maintained at a stabilized potential of approximately 50 volts, thereby clamping the positive peaks of the sawtooth at this level so that if the amplitude of the sawtooth exceeds 50 volts the right-hand section of valve 92 becomes conductive and changes capacitor 94 negatively, the resultant negative voltage being applied to control grids of pentodes 55 and 85, thereby reducing the rate of change of the time base capacitors and hence reducing the amplitudes of the time bases.