Abstract: A printed circuit board unit has smaller number of pins in connectors for connection of wiring (signal lines and power source lines) between a plurality of printed circuit boards for increasing mounting space of the board and interconnection method of wiring between printed circuit boards. The printed circuit board unit includes a plurality of printed circuit boards having wiring formed thereon, a part of the wiring on the printed circuit boards electrically connected through connectors, a screw formed of electrically conductive body and fixing the plurality of printed circuit boards with preventing the connectors from disengaging from each other, and remaining part of the wiring on the printed circuit boards electrically connected through the screw.

Abstract: An electric power supplier includes an alternating/direct current conversion circuit, a first path, a second path, a switch circuit, and a current detection circuit. The alternating/direct current conversion circuit converts an alternating voltage to a direct voltage. One end of the first path is connected to a first load. One end of the second path is connected to the first path, and the other end thereof is connected to a second load. The first and second paths supply output voltage of the alternating/direct current conversion circuit to the first and second loads. The current detection circuit detects a value of the output current flowing through a node between the first and second paths, and controls the switch circuit, formed in the second path, to electrically connect or disconnect the node to/from the second load, based on a detected current value.

Abstract: A back-electromotive force protection circuit that is able to protect circuit components other than a hard disc against the back-electromotive force generated in the hard disc. A back-electromotive force protection circuit includes a power source 10, a hard disc 20 having a positive side terminal connected via a connection line 22 to the positive side terminal of the power source 10 and having Ma negative side terminal connected via connection lines 24, 26 to the negative side terminal of the power source 10, a load 30 provided between the connection line 22 and the connection line 24 and a FET 40 for turning off the connection lines 24, 26 if no power is supplied from the power source 10.

Abstract: A printed circuit board unit has smaller number of pins in connectors for connection of wiring (signal lines and power source lines) between a plurality of printed circuit boards for increasing mounting space of the board and interconnection method of wiring between printed circuit boards. The printed circuit board unit includes a plurality of printed circuit boards having wiring formed thereon, a part of the wiring on the printed circuit boards electrically connected through connectors, a screw formed of electrically conductive body and fixing the plurality of printed circuit boards with preventing the connectors from disengaging from each other, and remaining part of the wiring on the printed circuit boards electrically connected through the screw.

Abstract: An electric power supplier includes an alternating/direct current conversion circuit, a first path, a second path, a switch circuit, and a current detection circuit. The alternating/direct current conversion circuit converts an alternating voltage to a direct voltage. One end of the first path is connected to a first load. One end of the second path is connected to the first path, and the other end thereof is connected to a second load. The first and second paths supply output voltage of the alternating/direct current conversion circuit to the first and second loads. The current detection circuit detects a value of the output current flowing through a node between the first and second paths, and controls the switch circuit, formed in the second path, to electrically connect or disconnect the node to/from the second load, based on a detected current value.