Journal of the Society of Motion Picture Engineers (1930-1949)

Record Details:

Title:
Journal of the Society of Motion Picture Engineers
Date:
1930-1949
Publisher:
New York, N.Y. : The Society
Volume:
Journal of the Society of Motion Picture Engineers
Leaf #:
000401
Language:
English
Collection:
Technical Journals
Format:
Periodicals
Contributor:
Prelinger Library
Sponsor:
MSN
Coordinator:
Media History Digital Library
Description:
The Journal of the Society of Motion Picture Engineers (SMPE)Êdocuments the technological progress of the film industry, highlighting technical developments in production and exhibition. Of special interest are articles about special effects, theater practices, lighting, and the introduction of the 16mm format. Initially titled "Transactions of the Journal of the Society of Motion Picture Engineers."Digitized by the Prelinger Library and the Library of Congress Motion Picture, Broadcasting and Recorded Sound Division.
Date Added:
July 19, 2022
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PHOTOGRAPHIC CHANNEL RECORDING AMPLIFIER BIAS OSCILLATOR MAGNETIC CHANNEL Fig. 4. Block schematic of dual recording channel. the photographic channel, the second being recorded by the magnetic channel. The photographic channel consists of a film loss equalizer, limiting and peakchopping amplifier, low-pass filter, lightvalve attenuator and noise-reduction amplifier. This photographic channel supplies the signal for the photographic modulator of the RA-1231-G Recorder. The magnetic channel consists of an attenuator, line amplifier, low-pass filter, recording amplifier which also provides equalization, and a bias oscillator and filter. The magnetic channel supplies the signal for the magnetic recording head in the RA-1231-C Recorder. The PEG mesh of the RA-1231-G Recorder is connected to an external amplifier which in turn feeds the monitor amplifier and speaker for monitoring the photographic channel. The magnetic monitor head in the RA-1231-C Recorder is connected to an external magnetic-reproducer amplifier which feeds the monitor amplifier and speaker so that the magnetic channel may be monitored. Suitable switching is provided so that the operator may select the channel to be monitored. Recording Frequency Characteristic Photographic Channel. The film loss equalizer plus the normal light-valve resonance rise is used to correct the frequency characteristic of the photographic channel. The film loss equalizer is so adjusted that when a constant level signal is recorded photographically, the resultant film will reproduce "flat" when referenced to the Research Council standard frequency film ASFA-2 5521 -A. The frequency response of the photographic channel from the input to the light-valve transformer is shown in Fig. 5. The film recording channel is so adjusted that the peak chopping point of the limiter occurs 1 db below the light-valve clash point. The limiter amplifier has a 20:1 ratio, the start of limiting being 2 db below the peak 392 November 1952 Journal of the SMPTE Vol. 59