International projectionist (Jan 1943-Dec 1944)

I. P. CONTEST (Continued from page 15) connecting a resistor of twice the value of the volume control between the two outside terminals of a wire wound control. This applies when there is an open in the winding. Now the volume control normally functions as a voltage divider. The signal voltage from the ground side of the control to the slider, which is connected to the grid, is then the voltage applied to the grid. If the open is below the normal setting of the control, the addition of the shunt resistor forms an L-pad in which the series arm is the volume control above the open in the winding. The shunt arm loads the input to the tube and its value determines the signal voltage available at the upper end of the series arm. Movement of the slider will vary the volume, but will not give the attenuation possible in the standard circuit; it can never reach the "0" voltage point. If the break is above the normal setting, the outside connections to the volume control should be reversed, that is, the ground side should be connected to the grid side of the coupling capacitor. Otherwise, there is no signal voltage on the grid and hence no sound. We are including this proposal as worthy in principle as, with proper selection of the value of the shunt arm, it is simple and sound can be restored quickly. George Beltz refers to the W. E. fader with "red" and "white" sides and proposes to substitute a radio volume control of proper resistance for each side with a single pole, double throw switch for changeover. Even though the W. E. fader is of the constant impedance type this arrangement should give intelligible sound. Maurice Rushworth has experimented with gelatines in front of his 3A photoelectric cell in a WE-86 type system and has found that three thicknesses of amber gelatine cut the volume in half, two thicknesses about 25% with no reduction of high frequency response, as the gelatine follows the slit. Due to the characteristics of the cell, however, it is quite possible that other colors of gelatine may seriously affect the response. Martin Teker would substitute two 500,000 ohm resistors in series for a volume control in the grid circuit, connecting the grid to the junction of two resistors. This would give a volume equivalent to normal setting. He would then remove a 60 ohm monitor volume control (which is always at full volume setting anyway) and connect it in series with the stage speaker line. In a low impedance stage line, this arrangement will probably give adequate volume adjustment. We hope it will have adequate current carrying capacity as the current in the stage circuit in the larger systems runs into amperes. Leo Vigil has used different colored gelatines in a similar emergency, light colors for increased volume, and darker colors for -decreased volume, and kept the show going. William Dugard has a very ingenious proposal in the form of a homemade carbon potentiometer made from an ordinary business card. With a soft pencil he makes a tapered dense black area along one long dimension of the card. At each end are sizable black areas for the connections. The slider consists of two alligator clips, one being moved at a time along the edge of the card to regulate volume, and then the other is removed. Thus the circuit is not broken, and by the use of clips insulated with fingers from rubber gloves, capacity effect and noise are minimized. He has actually tried this out in his system with satisfactory results. S.M.P.E. ATLANTIC COAST SEC. MEETS FEBRUARY 25 The next meeting of the S.M.P.E. Atlantic Coast .Section is scheduled to be held February 25 at the Hotel Pennsylvania, New York City. Henry Anderson, chairman of the Society's Sub-Committee of the Theatre Engineering Committee, will be the principal speaker. Mr. Anderson, who is manager of the insurance department for Paramount Pictures, Inc., will give a talk on "Flameproofing of Curtains, Draperies and Other Textiles." Among the topics to be discussed by other members of the Sub-Committee are "Fire Extinguishing .Devices for Motion Picture Theatres," by E. W. Fowler, National Board of Fire Underwriters, and "Use of Luminous Materials in Blackouts," by James Frank, National Theatre Supply Company. December Contest Winners First Prize FRED ERHARD P.O. Box 1130 El Paso, Tex. Second Prize GEORGE WILDE State Theatre Columbia, III. Third Prize M. J. NEDEROSTEK 2001 Green St. Allentown, Peiina. Winners of One-Year Subscriptions to I. P. GEORGE J. BELTZ 33 Ninth St. McMechen, W. Va. H. J. PLEXMAN 404 Murray St. Sudbury, Ont., Canada. MAURICE RUSHWORTH 531 S. Longwood St. Baltimore, Md. WILLIAM J. SCHMITZ 61 Oakdale Blvd. Pleasant Ridge, Mich. MARTIN TEKER Sheridan, Mont. LEO VIGIL East 212 Walton Spokane, Wash. Honorable Mention CHAS. W. COOK 119 Brown St. Santa Rosa, Calif. JESSE P. DELMORE 50 Cross St. Southbridge, Mass. WM. R. DUGARD 4670 Josephine St. Denver, Colo. CHAS. R. GLASER 4600 Smithfield St. Shadysidc, Ohio EARL H. GRIFFEN 390 Varney St. Manchester, N. H. CHAS. HARTUNG 237 N. Park Ave. Cape Girardeau, Mo. RUDOLPH KOLLER 219 Drake St. San Francisco, Calif. KEN PASCOE Nordic Theatre Marquette, Mich. FRED PEARSON 293 Hardin Ave. Toronto. Out., Canada RAY R1DGEWELL 79 Cumberland Ave. Portland, Maine 22 INTERNATIONAL PROJECTIONIST