Abstract: A jack is disclosed capable of selectively accommodating a first or a second plug, the first plug being used for data communication based on a first data communication standard, the second plug permitting data communication as per a second data communication standard. Also disclosed are a reproducing apparatus incorporating the jack and a data communication system furnished with the jack.

Abstract: A control circuit operating with a pulse-width modulated signal which is operative to control a driving circuit portion provided therein for driving a unit to be driven so as to operate in accordance with a pulse-width modulated control signal and in which an analog control signal is provided with a first DC voltage level at a biasing circuit portion (15), a triangular or saw-toothed waveform voltage signal which is obtained from a reference voltage producing circuit portion (17) with an amplitude varying in response to variations in a power supply voltage is superposed on both a second DC voltage level higher than the first DC voltage level and a third DC voltage level lower than the first DC voltage level, and a driving circuit portion (32) provide for driving a unit to be driven (43) is controlled with first and second pulse-width modulated control signals obtained from a level comparing circuit portion (30, 31) in which the level of the analog control signal provided with the first DC voltage level is com

Abstract: Start-control method and circuit for an optical disc play-back system according to this invention can allow the starting current of the system to be reduced considerably. The method includes the steps of loading the disc onto a disc drive motor, then finding the focal position of the lens, then powerfully energizing the disc drive motor for a certain period of time so as to start the disc spinning and then energizing the focus- and the tracking-servo circuits during inertial rotation of the disc drive motor. The circuit includes a disc-drive-motor servo switch capable of switching the power supply for the disc drive motor from the kick circuit to the disc-drive-motor servo circuit, a focus servo switch capable of switching the power supply for the focus servomotor from the focus search circuit to the focus servo circuit, and a tracking servo switch capable of initiating power supply to the tracking servomotor.