GB720126A - Function generator - Google Patents

Abstract

720,126. Electric analogue calculating apparatus. BENDIX AVIATION CORPORATION. Sept. 1, 1952 [Sept. 18, 1951], No. 21991/52. Class 37. [Also in Group XL (c)] An electric analogue generator of a hyperbolic or inverse function of the position of a movable element comprises an output impedance voltage divider energized by a highly degenerative voltage control circuit, having an intermediate tapping point adjustable by the movable element over a range of values changing the ratio of the divider impedances on opposite sides of the point, the voltage between the tapping point and a further tapping point on either side of the voltage divider being degeneratively applied to the control circuit input, and the desired function voltage appearing across the whole or a portion of the voltage divider and being applied to a utilization device. In Fig. 1 the movable element 12 of a variable width wave-guide antenna 11 is driven with oscillatory linear motion by a driving means 13 to scan the emitted beam hyperbolically in relation to the displacement of element 12. The linear motion correspondingly varies a resistance R1 in series with variable resistors R2, R3 in a chain energized from a D.C. source 15 through a current regulator tube 14 controlled by a high-gain amplifier tube 16 in known manner, whose control grid is energized by a voltage ei appearing between the slider of R1 and the negative end of the resistor chain. An output voltage eo appearing across the ends of the latter operates the deflection circuit 17 of a cathode ray tube 18, and it is shown that i.e. that the output voltage comprises a constant term and a hyperbolic function of the deviation of the movable element 12 in either direction from a fixed zero. The law may be adjusted to follow any desired hyperbolic function by variation of R2 and R3 with the addition of a D.C. zero level voltage, and the constant term may be eliminated by deriving an output voltage eh from the resistor R2. In a modification, Fig. 2 (not shown), resistor R1 is a poteritiometer having a fixed tap and a variable tap, the voltage eo is developed across the entire resistor chain, the voltage eh across R2 and the upper half of R1, and the voltage ei across R3 and the portion of R1 comprised by the variable tap, which is adjusted by the movable member. It is shown that the constant x varying between 0 and 1 accord. ing to the displacement of the movable member. In a further modification, Fig. 3, the resistor chain comprises two ganged equal variable resistors R2, a resistor R1 variable by a moving element, and a variable resistor R4, while the cathode of amplifier 16 is returned to a stabilized source of adjustable potential E. Voltage ei appears across resistors R1, R4 and the lower resistor R2, while voltage eo appears between the upper end of the resistor chain and earth in series with a stabilized adjustable zero level voltage Ec. Then it is shown that and the analogue function is adjustable to any desired hyperbola by varying the values of R1, R2, R4, E and Ec.