Journal of the Society of Motion Picture Engineers (1930-1949)

Record Details:

Title:
Journal of the Society of Motion Picture Engineers
Date:
1930-1949
Publisher:
New York, N.Y. : The Society
Volume:
Journal of the Society of Motion Picture Engineers
Leaf #:
00036
Language:
English
Collection:
Technical Journals
Format:
Periodicals
Contributor:
Prelinger Library
Sponsor:
MSN
Coordinator:
Media History Digital Library
Description:
The Journal of the Society of Motion Picture Engineers (SMPE)Êdocuments the technological progress of the film industry, highlighting technical developments in production and exhibition. Of special interest are articles about special effects, theater practices, lighting, and the introduction of the 16mm format. Initially titled "Transactions of the Journal of the Society of Motion Picture Engineers."Digitized by the Prelinger Library and the Library of Congress Motion Picture, Broadcasting and Recorded Sound Division.
Date Added:
July 19, 2022
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July, 1934] OPERATION OF HIGH-INTENSITY A-C. ARC 29 be outside the range of control of the arc-feeding mechanism. If, on the other hand, the current is too low, the copper will not melt away as far from the arc, the light will be very much reduced, and the current and voltage will not be constant. This condition results in FIG. 2. 8-mm. a-c. high-intensity carbons, underloaded: 60 amperes, 24 volts; showing different positions of the arc as it "flops" about on the ends of the carbons. an unsteady arc, which "flops" from the top to the bottom of the car- bon, as illustrated in Figs. 2(A) and 2(5). If the current and volt- age limits recommended in Table I are observed neither of these un- desirable conditions will be encountered. The illustrations of the arcs shown in this paper are all traced from actual arc images, and show the true relationship between the differ- ent parts of the arc. It is essential for good operation of the arc and good light projec- BALL SHAPED />^—^Si- HIGHLY LUMINOUS PORTION OF ARC x PORTION OF ARC LOWER LUMINOSITY FIG. 3. 8-mm. a-c. high-intensity carbons: 80 amperes, 25 l / 2 volts; good operating con- ditions. tion that the high-intensity a-c. arc be maintained within certain definite arc lengths and that it have a characteristic shape which is easily identified. Fig. 3 shows the high-intensity a-c. arc burning under the correct conditions at 80 amperes and 25 Y 2 volts between two 8-mm. carbons.