Motion picture projection : an elementary text book (1928)

Record Details:

Title:
Motion picture projection : an elementary text book
Date:
1928
Publisher:
New York : Technical Book Company
Volume:
Motion picture projection : an elementary text book
Leaf #:
000692
Language:
English
Subjects:
Motion Pictures, Motion Picture Technology
Collection:
Books
Format:
Books
Contributor:
Niles Essanay Silent Film Museum
Sponsor:
Media History Digital Library
Coordinator:
Media History Digital Library
Description:
Date Added:
September 21, 2023
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686 MOTION PICTURE PROJECTION The driving unit is a simple, two or three phase induction motor of ample capacity, running very close to constant speed regardless of load. The generator is of the constant current type. The design is bipolar, which lends itself most readily to constant current characteristics as shown in the curve. The field winding is shunt with interpole windings for commutation. The brushes and interpoles are so positioned relative to the main poles as to get a practically constant current over a wide range of voltage, which, in the double arc machine, reaches from 50 to approximately 115 volts. The position of the brushes on the commutator should never be shifted by rocking them, as this will change the entire characterization of the machine. If any sparking develops, it is due rather to imperfect brush contact than brush position. Operating Instuctions Have lamp carbons separated and lamp switches open. Close motor starting switch. Close that switch which controls lamp that you do not wish to use. Permit the generator voltage to build up before attempting to strike the arc, then strike the carbons together quickly and lightly, separating them immediately to about 1-16 of an inch, gradually increasing the separation as the carbons heat up until a proper length of arc is reached. (Note: 55 volts will then show on the Voltmeter,