Motion Picture Herald (Oct-Dec 1951)

|¥.V* breakoowns'$£ T. M. Reg. VELVET-SMOOTH DIRECT CURRENT FOR EVERY THEATRE REQUIREMENT For forty-five years Hertner Transverters have been continually improved to keep pace with changing conditions and developments. That’s why these Transverters are the leading power conversion units throughout the world for motion picture projection, providing velvet-smooth direct current regardless of changes in power supply voltages. The motor speed of the Transverter never varies when there are changes in AC line voltage because the motor speed is dependent on power supply frequency rather than voltage. Transverters are equipped with sealed-for-life bearings. Practically no attention is required other than casual inspection of the Transverter. Dependable Hertner construction assures long life and continuous, quiet operation with freedom from costly time-consuming repairs. There’s a money-saving, long-life Transverter model for every type of theatre. Standard Models are available from stock. 6 ryPES — FOR DELUXE THEATRES • DRIVE-IN THEATRES ■ SMALLER THEATRES • AUDITORIUMS lumens for the low-intensity system, to 5500 lumens for the 8mm suprex operating at only 60 amperes. Over and beyond the fact that the small suprex carbon systems can produce such greater quantities of light, we must consider that the quality of this light is so much better for projection. We all know that the low-intensity carbons produce light which is extremely yellow in color, whereas the suprex, because of the special cores, gives out beautifully clear white light. The reason for this can easily be understood by looking at Figure 3. THE COLOR FACTOR A light beam is a form of energy which is said to be radiating at certain specific wave lengths. White light, such as is visible to the human eye, is composed of, or is the addition of, all colored light, from Violet, which has a wave length 0.000017inch long, to Red, which has a wave length 0.00003-inch long. These clumsy fractional values have been changed for convenience to another unit. You will see from Figure 3 that white light is said to range from 4000 to 7000 Angstrom units. 5000 6oOO 7000 WavQlaH3k4 Umi+a FIGURE 3 — Comparison of the relative value of the color components in the light delivered by the sun, the high-intensIty arc, and the low-intensity arc over the portion of the spectrum which is visible to the human eye. Violet goes from 4000 to 4500 Angstrom units. Blue from 4500 to 5000, Green from 5000 to 5700, Yellow from 5700 to 5900, Orange from 5900 to 6100, Red from 6100 to 7000. White light can easily be broken up into its various component colors, and their proportional intensities can be measured. The dashed line in Figure 3 shows the composition of white light from the sun, or as we call it, daylight. The solid line shows the composition of light from the high-intensity suprex carbon arc. These two curves are so close as to be practically interchangeable. The dotted line shows the composition of light from a low-intensity carbon arc. TYPE "HI" for Suprex Type Arcs TYPE "HIH" for Suprex and Spot Arcs TYPE "HS" for 50-63 Volt High Intensity and Spot Arcs (for National Excelite 55,000 type lamp) TYPE "LV" for Simplex HIGH 1 KW Arcs TYPE "MA" for 50-70 Volt Low and High Intensity Arcs TYPE "CP" for 60-70 Volt High Intensity Arcs Distributed by NATIONAL THEATRE SUPPLY In Canada: GENERAL THEATRE SUPPLY COMPANY You can Count on Hertner for Power Conversion Leadership THE HERTNER ELECTRIC COMPANY A General Precision Corporation Subsidiary 12690 ELMWOOD AVENUE • CLEVELAND 11, OHIO MOTORS MOTOR GENERATORS GENERATOR SETS BEHER THEATRES SECTION 29