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GB726411A
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Improvements in thermionic valve amplifiers having an indicating device and particularly for use with magnetic sound recorders
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GB724613A
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Improvements in thermionic valve amplifiers
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GB691505A
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Improvements in and relating to magnetic heads for magnetic recording and reproducing apparatus
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GB667722A
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An improved photographic sound recording system for making either negative or direct positive sound records
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GB665967A
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Improvements in thermionic amplifiers
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US2518556A
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Shielding arrangement for magnetic sound apparatus
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GB662475A
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Improvements in and relating to apparatus for reproducing magnetic sound records
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GB662462A
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Improvements in and relating to magnetic sound recording and reproducing apparatus
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GB647041A
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Improvements in and relating to magnetic sound apparatus
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GB659067A
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Improved thermionic valve amplifying circuit
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US2677728A
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Process of and apparatus for developing visible sound records synchronized with invisible recordings on magnetic tapes
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US2512432A
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Process of and apparatus for locating sound signals on magnetic type sound record carriers
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US2477896A
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Adapter and holding means for picture film transparencies of different frame sizes in projecting apparatus
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IE17064L
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Optical projection apparatus
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US2324781A
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Arrangement for the reproduction of sound
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US2232920A
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Apparatus for the recording of asymmetric or normal sound films
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GB530673A
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Improved method and apparatus for expanding the volume range during the reproduction of sound films
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ES147416A1
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Improvements in the stabilization devices of the speed of the films for recording the sound of the same.
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US2210372A
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Speed stabilizing device for sound record films
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IE15545L
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Feeding mechanism for sound record films
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