Society of Motion Picture Engineers : incorporation and by-laws (1922)

Page scan 00040 from Society of Motion Picture Engineers : incorporation and by-laws

Record Details:

Title:
Society of Motion Picture Engineers : incorporation and by-laws
Date:
1922
Publisher:
New York : Society of Motion Picture Engineers
Volume:
Transactions of the Society of Motion Picture Engineers (1922)
Leaf #:
00040
Language:
English
Subjects:
motion pictures, Cinematography -- Periodicals
Collection:
Technical Journals
Format:
Periodicals
Contributor:
Library of Congress, MBRS, Moving Image Section
Sponsor:
Library of Congress, Motion Picture, Broadcasting and Recorded Sound Division
Coordinator:
Media History Digital Library
Description:
Preceeded by an unnumbered issue published in 1916 called: Incorporation and by-laws
Date Added:
September 12, 2024
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current value, say 90 amperes, multiply this by the resistance of .182 ohms which gives 16.3 volts and add the arc voltage of 60 volts, which gives 76.3 volts, which must be delivered by the generator. By inspecting Figure No. 3, however, we find that at 90 amperes, the generator only develops about 73 volts and will, therefore, not supply </ il fin m ■i (C\ i 3f 'f * 4 % Fig. 2A. Front View of Ballast Eheostat Fig. 2B. Eear View of Ballast Eheostat 90 amperes for the two arcs under these conditions. Suppose then that we try 82 amperes; we get 82X. 182+60 = 74.9 volts which falls on the curve as per Figure No. 3. Therefore, with one lamp operating, it will receive 55 amperes, whereas, with both lamps operating, the total current delivered by the generator is 82 amperes or 41 amperes per lamp. This is a decrease of approximately 25 per cent below normal, which will result in a decrease in the illumination produced by each lamp. When pictures are being projected, the motion of the 100 5 60 £ 40 *20 Fig.3 Current values obtained with one and. two arcs operated at 60 volts with 0.364 ohm resistance in series with each of the arcs 2 1 i i 0 tO 20 30 40 50 GO 70 60 90 100 110 Generator and Arc Amperes 30