Abstract: A light transmission module is disclosed, having a light receiving element module, in which a photodiode and a coupling portion between the photodiode and a first optical fiber are hermetically sealed, and a light emitting element module, in which a laser diode driven by an electric signal and a coupling portion between said laser diode and a second optical fiber are also hermetically sealed. A two-sided print board is provided, on the two sides of which electric circuits for a transmitting system and a receiving system are mounted. The electric circuits for the transmitting and receiving circuits are; isolated electrically from each other, and are sealed in one body by molds, and accommodated in cases, together with the light receiving element module and the light emitting element module.

Abstract: A magnetic tape shifting device comprises a movable member for carrying a plurality of reels and a driving mechanism for moving the movable member so that a desired reel carried by the movable member comes to a given position on a stationary member of the device. The movable member may comprise a rotatable member or a slidable member for carrying a plurality of payoff reels and/or takeup reels. The end of running magnetic tape may be detected by a photo detector for energizing a motor or motors which drive the movable member so that next reel will come to the given position immediately after the end of the operation of the former magnetic tape. The device according to the present invention may be applied to a tape recorder which produces a number of tapes by copying from an original or master tape, and time required for copying a number of tapes can be remarkably reduced because exchange of reels can be performed during operation of a magnetic tape of other reel.