ELECTRONIC TUBES
(Radio Electronics. Reel lesson 8) De Forest’s Training, Inc., 1948. 100 feet, b&w, 16mm. Summary: Actions, functions, and characteristics of the vacuum tube. Shows that since the changes of grid voltage can be duplicated only by larger changes of plate voltage, the triode tube acts as an amplifier
Registration MP3901 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.
Catalog entry
Catalog of Copyright Entries, Third Series, Parts 12–13: Motion Pictures, 1949, Internet Archive catalogofcopyri331213libr (OCR text), lines 3995–4007.
ELECTRONIC TUBES. (Radio Electron- ics. Reel lesson 8) De Forest’s Train- ing, Inc., 1948. 100 feet, b&w, 16mm. Summary: Actions, functions, and characteristics of the vacuum tube. Shows that since the changes of grid voltage can be duplicated only by larger changes of plate voltage, the triode tube acts as an amplifier. © De Forest’s Training, Inc.; 10ct48; MP3901.
Copies on the Internet Archive
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