F. H. Richardson's bluebook of projection (1935)

Record Details:

Title:
F. H. Richardson's bluebook of projection
Date:
1935
Publisher:
New York : Quigley Publishing Company, Inc.
Volume:
F. H. Richardson's bluebook of projection
Leaf #:
00058
Language:
English
Subjects:
Motion Pictures, Motion Picture Technology
Collection:
Books
Format:
Books
Contributor:
Media History Digital Library
Sponsor:
{"Media History Digital Library","Jeff Joseph"}
Coordinator:
Media History Digital Library
Description:
Date Added:
August 01, 2024
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40 RICHARDSON'S BLUEBOOK OF PROJECTION would supply approximately 80 volts, eliminating the enormous waste. (35) Waste may be denned roughly as all power delivered to a projector circuit in excess of 80 volts. We except the case of a 110 volt d. c. supply since here it would cost usually as much or more to eliminate it. We except also those situations where the stability requirement is somewhat below or in excess of 80 volts. Resistance Elements In breaking down voltage in the rheostat the power is transformed into heat. Hence the material used in the rheostat must be able to withstand high temperatures, though (36) such temperatures should never exceed a very dull red when viewed in a dark room. Figure 9 (37) Certain wires, known as "resistance wires," are wound into coils, each spiral separated approximately % inch from adjoining spirals; a number of such coils connected in series with each other constitute one type of rheostat. Iron of a certain grade cast into a "grid" and several of these grids connected into series with each other, is another popular rheostat element. The coil and grid types are illustrated in Fig. 9. (38) These coils or grids are mounted upon a suitable metallic frame from which they are thoroughly insulated, usually by mica. Though details vary, the coil or grid is