Boxoffice (Jul-Sep 1947)

PORE ST 40 to 75 amperes fi-Ue RECTIFieHS MODEL 7S-V-6 . . . The result of highly technical knowledge gained from building rectifiers for radar and other intrinsic scientific devices — achieving a new high for rectification efficiency at the lowest possible cost of power. Designed for all theatres using Suprex or Simplified High Intensity Projection. Built-in remote control relays with provisions for operating spotlights. Full 3-phase rectification. No moving parts. Power with flexibility — constant and uniformly smooth current — no flicker. Quiet and ease of operation. Sturdily constructed all steel case. Insist on the Best - Forest Products: 75-V-6 Rectifiers, Super MCS, LD-60 and LD-30 Bulb Type Rectifiers, & ^ Rectifying Tubes and Sound Screens. ^ FOREST Mfg. t^rp., eo Park PI., Newark, N.J. /! In /JdiMznced £^n(^dnee444t4^ i I VISIT FOREST BOOTH No. 30 at TESMA TRADE SHOW, Washington, 0. C Major Advances Claimed lor New Suprex C-70 Arc Lamp (Continued from page 49) dilating clutch moves into position for the next forward feeding cycle. “The C-70 duplex clutch does its job admirably. Two extremely accurate triplex roller clutches are mounted on the feed shaft. One oscillates and feeds the carbon forward; the other locks positively and prevents even the most minute slippage in the predetermined feeding rate of the oscillating member. Each of the six rollers (three to each member) are ground to a tolerance of IdO.OOO inch and are hardened to resist wear. An unlimited number of feed ratios are available through fingertip control. “This precise feeding of the carbons means that 1^ positive carbon crater will remain at the p6int of maximum effective focus of the reflector, and that the negative carbon will be held exactly at the proper arc gap; that is, at a predetermined distance from the positive crater. This insures screen light of maximum brilliancy with insignificant light variations. In short, a dollar’s worth of screen illumination is provided for every dollar expended on current and carbons. "Another vitally important control element in a Suprex lamp is the means employed for stabilizing the arc flame. This WHEN MAKING INQUIRY ON PRODUCTS OR SERVICES ADVERTISED HEREIN. PLEASE BE SPECIFIC IN MENTIONING THE POINT THAT YOU "SAW IT IN The MODERN THEATRE section of BOXOFFICE." r I I I I I I I I I I I YOUR ASSURANCE OF THE BEST! > WENZEL "SmooHi-Running” PROJECTOR You are assured of "smooth-running" performance with the Wenzel timeproven projector. Use Wenzel's precision replacement parts . . . and your present equipment will do a smoother running job. WENZEL "BULL DOG” "Will Never Lose Its Grip” The Bull-Dog AR-15 — engineered by Wenzel to eliminate key breakage on all types of shafts for winding film. Also for use in the Lower Magazines to more evenly distribute the pull strain. For automatic and hand rewinds too. When ordering, give model number or maker of shaft, together with shaft diameter. Write for Folder No. WC19 Write for our Complete Catalog. We will sell only through Independent Theatre Efpjipment Healers. Mention the dealer serving you. on PRO-4 projector mechanism. UieNZEL P R O J C GTO W£AN Y 2505 19VS“=Slrait£SliEET C m C Fig. 5. C-70 arc stabilizer method: Positive carbon (1) extends through loop (3). Magnetic tlux (2) encircling carbon is collected by the loop which through induction, exerts magnetic iorce at its ends (4) which in turn forces upward the gas ball at the end of carbon (5). This prevents flame from enveloping the end of positive carbon. Magnetic force may be increased by bending ends of loop toward the arc. Ideal arc is when lower edge of flame is at straight line as at (6). has been accomplished heretofore by placing magnets of various kinds behind the reflector, which may burn out and deteriorate over a period of time as a result of continuing exposure to the intense heat of the arc. “The method of arc stabilization employed in the C-70 utilizes a loop of steel which, mounted on the carbon guide, surrounds the positive carbon (Fig. 5). The ends of this loop are bent under the arc a distance equal to the protrusion of the carbon through the guide. This loop is magnetized only when the arc is burning. The magnetic flux encircling the positive carbon is collected by the loop which, through induction, exerts an upward magnetic force and thus stabilizes the arc by forcing up 54 The MODERN THEATRE SECTION