GB1169713A - Transductor Circuits - Google Patents

Abstract

1,169,713. Automatic current control and regulation. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. April 26, 1967 [May 19, 1966], No.22316/66. Headings G3R and G3X. In a control system of the type wherein the inherent regulation characteristic of a transductor 5 maintains constant the current through a variable load 7 (e.g. a number of lamps) over a range of values of the load, the D.C. excitation of the transductor is pre-set in accordance with a signal from a fixed reference source 14 applied to an emitterfollower transistor amplifier 11 controlling the transductor excitation winding 12. Additionally the excitation is made dependent on the output voltage of the transductor to prevent the reduction of R.M.S. current through the load 7 which occurs with increase of the transductor output voltage consequent upon an increase of the load 7 beyond the range, Fig.2 (not shown), this current varying with the form factor of the transductor output which in turn varies with the output voltage. As shown, the transformer 6, 8 supplying the load 7 has an additional secondary winding 9 whose output is rectified to charge a capacitor C1 whose voltage is applied through resistors R4, R6, R7 to the base of a transistor TR1 connected across part of the reference source potentiometer network R1, R2 from which the control signal for the amplifier 11 is derived. In operation, an increase in transductor voltage is reflected through the winding 9 and feedback circuit C1, R4, R6, R7 to make transistor TR1 more conductive and so alter the signal to the amplifier 11, the compensating effect being matched to the transductor characteristic by adjustment of the resistor R5 (which forms with the diode MR2 a non- linear potential divider) and of the tap setting of the resistor R7. A typical compensating effect is described, Fig.3 (not shown).