Motion Picture Herald (Jul-Sep 1931)

September 26, 1931 Motion Picture Herald 13 of the moving arm of the dimming fader. All preset potentiometers and the individual potentiometer are in turn connected to a pilot switch, which either connects them to direct feed or through the master potentiometer. The master potentiometer is energized directly from the control bus. Any number of similar circuits may be connected and controlled by the master potentiometer, by throwing their corresponding pilot switches. As already stated, all controls are mounted on the movable console, which is located on the stage (or may ride the orchestra lift), while the reactors and tube units are assembled on the reactor rack in the basement. Close to the rack is a motor generator set and its control panel. This motor generator set is used to supply the necessary power to the control equipment. The main d. c. control source, which is normally 42 volts, is supplied by the main generator. This generator feeds power to all individual, group-master, and sub-group master potentiometers, in addition to all constant voltage buses. Driven by the same motor is the grand-master generator that feeds the variable voltage grand-master bus. Field control of this generator by a grand-master potentiometer on the console, in series with a rheostat on the . motor generator set panel, accomplishes the required results of master dimming. And lastly, on the same shaft, is mounted a 180 volt d. c. generator, which feeds direct current to the vacuum tubes. A power source of 115 volts, 60 cycles is also required, and this is taken from the main feed to the lamp loads. THE THERMIONIC type of control falls into three major divisions: (a) Control console, {b) relay cross connecting panels, and (c) reactors and tube units. Each will be treated separately. Control Console As previously mentioned, the console provides flexible control of 110 lighting circuits by 36 dimming controls, and by four additional controls that do not pass through the cross connecting network. These latter are permanently connected to the down-lights in the auditorium. All equipment mounted on the console can be grouped into the following divisions : {A) Cross connecting switches enabling the switching of any one, or up to 10, of the 110 load circuits, to anyone of the 36 individual controls. These switches are located on the diagonal sides of the board in the vertical faces, 55 on either side. {B) Thirty-six individual control drums, which remotely control the dimming of whatever load circuits are connected to them by the switching under {a). (C) One four-scene preset dimming de vice associated with each individual control, but with individual scene faders mounted and operated by a common gang shaft by motor or handwheel. Equipment under {b) and (c) is located on center keyboard of console. (Z)) Four group master potentiometers, foot, handwheel or motor operated, each capable of electrically controlling any combination of the 36 individual controls that it may be desired to connect to them. (£) Nine sub-group master potentiometers, foot-pedal-operated, each capable of electrically controlling any or all of the corresponding sub-group of four controls. {F) Four individual control drums located on the left inclined panel, and one master for dimming the house direct circuits. The master potentiometer may be foot-, handwheel or motor-operated. {G) One grand-master potentiometer, foot-, handwheel or motor-operated, capable of electrically controlling any or all individual controls or group controls. {H) Remote individual control for 20 four-color boomerangs on spotlights. These controls are located on the right vertical panel. (/) Remote individual "Joy Stick" control for directional and focusing of nine spotlights. (7) Signals and remote iris diaphragm control to nine arc spot positions. Con