Projection engineering (Jan 1932-Mar 1933)

Page 26 PROJECTION ENGINEERING New Developments and News of the Industry S BIG P-A. JOBS TO SAMSON The Samson Electric Company, Canton, Mass., reports receiving orders for one of the largest group address jobs so far planned covering the new recreational building of Louisiana State University, and the Fine Arts Building of Louisiana State University, both of these buildings being on the campus at Baton Rouge, Louisiana. The total net amount of Samson equipment at contractors' prices used for this installation is $51,000.00. Both of these installations are very elaborate, particularly the Fine Arts Building, where they have two theatres in the building. There are microphones to a total of 24 in the installation, most of which are condenser microphones. In both installations are reproducing microphone pickup, phonograph records and radio programs throughout the building. In the Fine Arts Building it is possible to pick up a program by microphone in any one of the rooms of the building, and transmit it to any or all of the other rooms of the building. The equipment is all special, and will take approximately 3 months to build. NEW SOUND HEAD The Goodall Electric Company, Ogalalla, Neb., announces a new sound head. There are no moving parts in this sound head, no springs or gates, yet the film when passing in front of the light beam maintains a perfect semi-circle, thus keeping the film in focus against the light beam at all times regardless of how badly buckled the film may be. By a special arrangement, the film is pulled past the sound aperture at a constant, even speed thus eliminating all "flutter" and uneven tones. Standard exciter lamps of any size are used. A special optical system throwing a light beam of .0007 inches is used. The GM caesium P. E. cell is entirely shielded, both electrically and from stray lights, by a hollow aluminum cell house in which the P. E. cell is always held at the proper tension and position. Another novel feature is the adjustable aperture plate and guide roller making it possible to adjust either the film or the aperture plate while the equipment is in operation. CONDENSER MICROPHONE The Shure Brothers Company, 337 West Madison St., Chicago, with reference to their new condenser microphone, state : "This instrument is designed to meet the most exacting requirements for high quality radio broadcasting, sound recording, and sound measurement tests. Its outstanding characteristic is its relatively uniform response to all frequencies from 40 to 10,000 cycles. In the special design of its amplifier are combined the advantages of high output level with extreme wealth of richness in tone quality. Its reproduction is so realistic as to make it difficult for even the trained ear to discern the use of the instrument between the original source of sound and the listening ear." ▲ MODEL 603 ILLUMINOMETER An instrument has recently been developed which reads illumination intensities with the same ease and facility as reading ammeters and voltmeters. This instrument was developed by the Weston Electrical Instrument Corp. of Newark, N. J. and is know as their Model 603 Illuminometer. It consists of an indicating instrument and a light target assembled in a portable case. The light target is on the end of a flexible cord so that it may be placed in any position. This light target or searching unit has two Photronic cell units which convert light energy directly into electrical energy without the use of batteries or other auxiliary voltage. They maintain constant output over long periods of time and there is no dark current. The output from the Photronic cell units is considerable, allowing the use of a rugged portable instrument calibrated directly in footcandles. There are three ranges on the instrument, namely 10, 50 and 250 foot-candles. A range changing switch is provided for the selection of the desired scale. Other combinations of ranges are being added to the line and will be available shortly. The light target may be placed at a distance from the" observer so that shadows and lights reflecting from light clothing will not cause errors in readings. Light may be read from all angles and the light target may be placed in relatively inaccessible places, in show cases, windows, etc. The absorption of light by painted walls, screens, draperies, etc. can be measured directly by turning the light target so that it faces the surface. A MOVABLE SWITCHBOARD FOR THEATRES One of the difficulties the smaller theatre producers often meet with when leasing a theatre or auditorium for their season's presentation is either the absence of, or an inadequate, switchboard installation with proper dimmer equipment. To provide additions to the existing equipment or order the erection of a new switchboard not only puts an added burden of expense upon the producer, but the very nature of the equipment is such that it becomes a fixture of the building under the terms of the lease, and the tenant must leave it behind when he moves out at the close of the season. This disadvantage has been overcome by a semi-portable switchboard built by Kliegl Bros., New York — which while having all the gradations of control to be found in permanent equipment, as well as being extremely flexible in the matter of circuit connections and combinations, can also be removed from the premises as a complete unit, and used again at the next location by simply connecting the feeder cable to the source of supply. While primarily intended for little theatre producers, this semi-portable switchboard may also be used to advantage by national exhibitors, novelty display advertisers, and others requiring equipment of this character — its design being modified to meet their particular needs. NEW AMPLIFIER TUBES Jenkins and Adair, 3333 Belmont Ave., Chicago, have brought out three new tubes suitable for the Standard C amplifier panel, C monitor panel and C volume indicator panel. These tubes are particularly adapted to speech frequency amplification. The characteristics of these tubes are: Fila Fila ment merit Plate Plate Current Volts Plate Current Hesist Type Amp. V. Volts M.A. Mu ance J&A 102 .98 2/2.5 135 V. .5/1.0 28/30 50.000 .7&A 205 1.6 4.5/5 350 Max. 20/35 6.5/7 3,500 J&A 211E 2.5 10 750 Max. 65 12/14 4.000 ARCTURUS REDUCES PRICE OF SCREENGRID TUBE Effective December 14 the Arcturus Radio Tube Company, Newark, N. J., announced that it reduced the list price of the Type 122 d-c. screen grid tube to $3.00. CONDENSERS WITH 2000 VOLTS D-C. TEST 1, 2 and 4 microfarad condensers which stand a 2,000 volts d-c. test, 1 to 4 microfarad condensers of 1,500 volts d-c. test, and .01 to 4 microfarad condensers which pass a 500 volt of d-c. test are being marketed to the sound laboratories, studios and projection booths by Morrill and Morrill, 30 Church St., New York. The company also handles a dependable line of a new type of carbon resistors.