International projectionist (Jan-Dec 1935)

24 INTERNATIONAL PROJECTIONIST MICRO-RECORDS of the SCANNING BEAM help to attain better sound Here is the story of two exciter lamps and one lens system. The wrong combination of lamp and optical system, at the left, fails to reproduce the sound as recorded on the film. The beam is uneven in brightness and fades off before it reaches the edges of the sound track. The correct combination , at the right, covers the full width with more uniform brightness and radically improves the reproduction. SUCH records taken with the micro-photometer of the Nela Park Engineering Department make it easy to determine the brightness in each one-thousandth of an inch along the tiny scanning beam for any lamp and optical system. This helps us to determine the type of filament which is best adapted to any one lens system; and to work with optical designers in developing better combinations of lamps and lens systems for accurate sound reproduction. The importance of this work to the projectionist and exhibitor is twofold: when the brightness of the scanning beam is uneven, you can not secure true reproduction of the recorded sound; and when the light is too low in brightness, the cost of reproduction is increased. General Electric scientists and engineers are constantly making studies such as these to insure that Edison Mazda photo-cell exciter lamps will give you faithful reproduction of sound ... at low cost. General Electric Company, Nela Park, Cleveland, Ohio. EDISON MAZDA LAMPS GENERAL (#) ELECTRIC Clayton Quality Products • Clayton even tension take-ups are made for all projectors and sound equipments. • Also the maker of the Clayton combination even tension winder and brake. CLAYTON PRODUCTS CO. 31-45 Tibbert Avenue New York, N. Y. May 1935 New Metal Tubes Induce Stiff Trade Fight NEW metal radio tubes, which tests indicate to be of greater continued efficiency of operation than the glass type now in use, have been announced by General Electric. These new metal tubes are not only much smaller and more sturdy, but offer many improved electrical characteristics over the conventional tubes of today. They provide their own shielding and the metal shell is a better heat conductor and radiator than glass. The short leads of the tubes permit greater amplification at the higher frequencies and the more effective shielding insures greater stability. These tubes are not interchangeable with glass tubes. The metal tubes are cylindrical in form, some in reduced diameter at the top. Others, such as a r. f. amplifier, have a terminal at the top extremity. Each lead-in wire passes through a tiny bead of special glass that is fused securely within an alloy eyelet, which in turn is welded to the metal container, thus assuring a long life vacuum. This alloy, having substantially the same coefficient of expansion as glass, is known as Fernico and is a combination of iron, nickel and cobalt. It was developed expressly for the purpose of a perfect seal on the new tubes. Smaller, Stronger, Better Shielded In the main, the new tubes are less than half the size of the familiar glass tubes of corresponding rating. The metal shells are, of course, much stronger than glass bulbs, and not subject to breakage, while the use of short, New metal tubes (actual size) stiff supports in the new tubes results in less mechanical vibration of the internal elements. Elimination of the glass "pinch seal," in which all leads and supports are concentrated in the glass tubes, allows the leads to enter the header of the new tube at the proper points for short, direct paths. Also, the new design permits a logical arrangement of connec