Richardson's handbook of projection (1930)

Record Details:

Title:
Richardson's handbook of projection
Date:
1930
Publisher:
New York : Chalmers Publishing Company
Volume:
Richardson's handbook of projection
Leaf #:
000185
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:
March 28, 2024
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MANAGERS AND PROJECTIONISTS 1109 Western Electric Disc Record Pick-up System IN order to grasp and understand the manner in which the Western Electric Company disc record sound pick-up operates, it is necessary to be aware of and understand one of the fundamental laws of electric and magnetic action upon which the action of the pick-up is based. According to this fundamental law, if a coil of wire is wound around an iron bar (called a "core") which can be magnetized, whenever and as often as the magnetism in that core is in any degree altered or changed, a voltage will be generated in the coil while the magnetism is changing, which voltage will be in exact proportion to the amount or rate of change in strength of the magnetic field. No voltage will be generated so long as the magnetism remains steady, but only while a change in magnetic density is taking place. This is a principle with which many projectionists will be more or less familiar through having studied the action of transformers. It is the principle upon which disc record sound pick-up, as applies to Western Electric' equipment, depends for its action. HOW MAGNETISM IS ALTERED.— Given such a coil and core as is above described, one method by means of which the magnetism of the core may be changed is to place it "across" the terminals of a U-shaped (horse