Richardson's handbook of projection (1927)

Record Details:

Title:
Richardson's handbook of projection
Date:
1927
Publisher:
New York : Chalmers Publishing Company
Volume:
Richardson's handbook of projection
Leaf #:
000510
Language:
English
Subjects:
Motion Pictures, Motion Picture Technology
Collection:
Books
Format:
Books
Contributor:
Media History Digital Library
Sponsor:
Media History Digital Library
Coordinator:
Media History Digital Library
Description:
Date Added:
September 28, 2023
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958 HANDBOOK OF PROJECTION FOR AUTOMATIC DOUSER AN ELECTRIC DOUSER.— The change-over is facilitated by what is known as the Weaver Electric Douser, which works by magnetic action and cuts off the light from one projector, substituting that of the other simultaneously, or at least in the very small fraction of a second. The action is in fact so rapid that it is practically instantaneous. In Fig. 378 we have the photographic view of the douser, and in Figs. 379 and 380 wiring diagrams for two and three-projector installations. It is also quite possible to add other switches so that the douser may be set into acion from any desired point in the projection room, through this latter we do not either, value or recommend, because we hold that the Figure 378 projectionist should be beside the projector, where he rightly belongs when a picture is being projected. The douser is clamped to the top of the condenser cone by means of a market. One push button switch is located on or near to each projector. It is possible to locate other push buttons at the re-winder table or elsewhere, if desired. These switches must, however, be of such type as will make contact ONLY when the button is pressed down. If the current be D C, then it is advisable to use an "H and H" switch. In any event if the current be DC a switch that will not arc must be selected. If the current be alternating, then any type of momentary contact may be used.