GB757442A - Regulating apparatus - Google Patents

Abstract

757,442. Electric - control systems. GUGELBERG A. VON, [trading as ELESTA ELEKTRONISCHE STEUERAPPARATE, DR. A. VON GUGELBERG]. May 4, 1954 [Dec. 7, 1953], No. 13001/54. Class 40(1) [Also in Group XL(b)] In a control apparatus in which current through a photocell, ionisation chamber, or a resistance dependent on light or other radiation, temperature, pressure or other physical variable controls a pair of gas discharge tubes each with a cathode, anode, and starter electrode, the latter are connected through the photocell, &c., and are each connected through high resistance elements to a bias supply. The discharge circuits containing the anode and cathode of each tube each include a series connected resistor and are fed from a common D.C. source and means are provided, including an electric coupling element for coupling the discharge circuits which on firing of one of the tubes always extinguish the other ignited one. In the twilight switch (Fig. 2), for operating road, office, shop-window, &c., lamps in response to changes in ambient illumination two cold cathode discharge tubes 2, 3 with trigger electrodes between which a photocell 1 is connected are supplied with stabilized voltage via rectifier 19, smoothing capacitor 20 and stabilizer tubes 22, 23, bias for the triggers being tapped off the stabilizer voltage through high resistors 4, 5. When, for instance, tube 3 is conducting, i.e. with high illumination of photocell 1 its trigger potential is determined by the discharge whereas the trigger potential of tube 2 controlled under fixed illumination conditions by the value of bias tapped off potentiometer 6 is set so that tube 2 is extinguished. When the level of light falls below a preset value the trigger voltage of 2 becomes sufficient to ignite it. The consequent increased voltage across common resistor 12 together with the voltage across capacitor 11 which is temporarily maintained causes a sharp fall in potential across tube 3 thereby extinguishing it. Moreover, when the discharge ceases the trigger potential, now controlled by the bias from potentiometer 7 is insufficient to re-ignite it. Discharge through tube 2 is maintained until the illumination rises above a level determined by the variable bias from potentiometer 7 when tube 3 is re-ignited. The resulting increased voltage across resistor 12 and the stored voltage on capacitor 9 causes tube 2 to be extinguished. While tube 2 is conducting the load circuit 16 containing the lamps is completed by the contacts of relay 18. Capacitors 13, 14 prevent momentary changes in illumination from flashing the lights. In an alternative arrangement the relay winding 18 is replaced by a resistor and the potential available at the anode of 3 or cathode of 2 is used to control thyratrons which control the lighting circuits. A similar circuit, Fig. 1, not shown, may also be used for control in response to changes of, e.g. pressure, temperature and intensity of radiation other than light by substituting for the photocell elements the resistance of which is a function of these variables.