F. H. Richardson's bluebook of projection (1942)

Record Details:

Title:
F. H. Richardson's bluebook of projection
Date:
1942
Publisher:
New York : Quigley Publishing Company, Inc.
Volume:
F. H. Richardson's bluebook of projection
Leaf #:
000465
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 21, 2024
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CHAPTER XIX POWER SUPPLY FOR SOUND SYSTEMS Nearly all the constituent parts of a sound installation require the application of electrical power of some kind, though the requirements vary considerably. Direct current at several voltages is needed, and more than one voltage of alternating current. It will be advisable, for several reasons, to consider both the power requirements, and the methods used to meet them, before examining the apparatus in which that power is to be used. One of those reasons lies in the fact that (as has already been explained) the study of amplifier drawings is greatly simplified if the built-in power system can be recognized for what it is, and thus eliminated from any possible confusion with the amplifying action proper. Varieties of Power Needed (1) The list below must be taken as only a rough outline. Exciting Lamps: d. c. or a. c, but most often d. c. Usually 8 to 12 volts, 2 to 4 amperes. Photoelectric Cells: d. c. only. Usually 90 or 135 volts and only a minute fraction of an ampere. Microphones: (Sometimes none) d. c. when used. Most commonly V/2 to 12 volts; less than *4 ampere. Drive Motors: a. c. where possible; line voltage, usually 110. Amplifier "A": d. c. sometimes; a. c. usually. One to 10 volts; % to 12 amperes. Amplifier "B": d. c. always. Up to 1,000 volts; % ampere. Occasionally still higher power. Amplifier "C": d. c. always. Usually less than 50 volts; almost zero amperage. 449