Abstract: A method of and an apparatus for synchronizing reproduction using a plurality of video information reproducing systems are arranged such that synchronization pulses contained in video signals are integrated for each recording medium using as a starting point a required video position identifying signal recorded on each recording medium, and integrated values are made to coincide with each other, thereby allowing the video information of all the recording media to be reproduced synchronously. Thus, since synchronization of reproduction is effected while the reproducing systems are operating, there is no need to temporarily stop the reproducing systems as has been done conventionally. Consequently, if it is possible to effect synchronous reproduction even in the case of a CLV-type disk which cannot be temporarily stopped. In addition, the time duration required for synchronization can be reduced.

Abstract: A noise-free electronic switching circuit selects one of a pair of audio input signals in an audio system. Each input signal is connected by separate conductors to a single output terminal. The output terminals of two transistors are respectively connected between each conductor and ground. When a manually-operated switch is switched to a first operating condition, an exponentially increasing and an exponentially decreasing control voltage are respectively applied to the bases of a first and a second transistor. When the actuating switch is switched to a second operating condition, an exponentially decreasing and an exponentially increasing control voltage are respectively applied to the bases of the first and the second transistor. In either operating condition, one transistor is turned on and the other is turned off. Thus, only the selected audio signal is delivered to the output terminal; and the other non-selected audio signal is shorted to ground before reaching the output terminal.

Abstract: A play/record switching circuit for an electrical signal reproducing and recording apparatus having inputs for source data signals and a microphone data signal, and a tape head for generating a tape head reproducing signal and for receiving one of the data signals to be recorded. The circuit includes one mechanical switch for selecting one of said signals, another mechanical switch for selecting either a play or a record mode, and electrical amplifiers for processing the various signals and for monitoring the processed signals. Positive- and negative- logic-controlled electronic bilateral switches are controlled by a D.C. voltage control signal for selecting the appropriate processing amplifier and the appropriate monitor amplifier in dependence upon which mode has been selected and which signal has been selected by both mechanical switches. The electronic amplifiers and the bilateral switches and the D.C. control signal circuitry are all incorporated on a single integrated circuit chip.