ALTERNATING CURRENT PRINCIPLES

ALTERNATING CURRENT PRINCIPLES. (Radio Electronics. Reel lesson 6) De Forest’s Training, Inc., 1948. 100 feet, b&w, 16mm. Summary: Explains the principles of alternating current--how alternating current is developed, what its operating characteristics are, and how the a-c transformer works

Registration MP3899 No renewal found

Term began: 1948-10-01
Claimant: De Forest’s Training, Inc
Class: MP — published motion picture other than a photoplay (numbering series begun 1946)
Finding: no renewal entry found for 1975-1977 in the CCE motion-picture renewal sections
In the public domain since: 1 January 1977 (end of the 28th year, no renewal)

A renewal would have appeared in the Copyright Office's renewal registrations 27 to 29 years after the term began. Those volumes are loaded and no matching renewal was found. A work published 1931–1963 that was not renewed entered the public domain at the end of its 28th year.

A renewal had to be filed in the 28th year and would be listed in the 1975 or 1976 volume; volumes searched: 1975, 1976, 1977.

The renewal sections are OCR text of printed volumes; a damaged record can hide a renewal. Before relying on this, search the linked volumes yourself for the title and for number MP3899.

Catalog entry

Catalog of Copyright Entries, Third Series, Parts 12–13: Motion Pictures, 1949, Internet Archive catalogofcopyri331213libr (OCR text), lines 804–816.

ALTERNATING CURRENT PRINCIPLES. 
(Radio Electronics. Reel lesson 6) 
De Forest’s Training, Inc., 1948. 100 feet, 
b&w, 16mm. 

Summary: Explains the principles of 
alternating current--how alternating 
current is developed, what its operating 
characteristics are, and how the a-c 
transformer works. 

© De Forest’s Training, Inc.; 10ct48; 
MP3899.

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