GB649779A - Improvements in or relating to electronic multiplying and dividing means - Google Patents

Abstract

649,779. Multiplying circuits. MINISTER OF SUPPLY. Nov. 21, 1947, No. 30926. [Class 40 (i)] In a system for generating a signal representative of the product of two quantities, a rectangular wave having an amplitude proportional to the multiplicand, and a second wave having a phase relative to the first wave representative of the multiplier are generated and combined in a circuit to produce the output signal. Valves 5, 6, Fig. 1, operate as a 1 Kc/s. multivibrator producing square waves, Fig. 2, a, b, at the respective anodes. The waves are limited by diodes 7, 8 and 10, 11 to give waveforms, Fig. 2, c, d limited at an arbitary value, 40 volts and earth for the first wave and 40 volts and Vy, the multiplicand signal applied at terminal 12, for the second wave. The algebraic sum is fed to the cathode follower 14 to give an output, Fig. 2, e. A signal Vx, representing the multiplier is applied over terminal 18 to cathode follower 19 which sets the level on clamping diode 21 connected to the anode of phantastron 20. Upon the wave from valve 6 going positive, valve 20 passes current. to the anode and the run-down of anode potential occurs, Fig. 2, f. The duration of the run-down time is dependent on the initial anode potential and thus on the input voltage Vx. As the end of the run-down, phantastron 23 is triggered over coupling capacitor 24 to give a fixed run-down time and delay of one half-period of the waves. During this fixed time interval, switching valve 26 is cut-off, Fig. 2, h, hatched area, so that the anode potential may rise and diode 29 conduct. A low-impedance instrument is connected across terminals 28, the current passing through it appearing as at Fig. 2, j, the negative going portions being provided by current through adjustable resistor 43. The multiplying circuit may be employed to obtain ydx or 1/x from y and x, Figs. 3 and 4 (not shown).