Abstract: A battery charger includes a plurality of rectifier, a plurality of switches respectively for the plurality of rectifier elements, a zero-crossing detector, a switch controller, and a detection reference changer. The plurality of rectifier elements rectify AC voltages of three phases output from a power generator. The plurality of rectifier elements, in an off-state, causes the plurality of rectifier elements to rectify the AC voltages to charge a battery. The plurality of rectifier elements, in an on-state, causes the AC voltages to be short-circuited to a negative side of the battery. The zero-crossing detector detects zero-crossings of the AC voltages. The switch controller outputs, based on the zero crossings, a gate signal for turning on and off the plurality of switches. The detection reference changer changes a reference for the zero-crossing detector to detect the zero crossings.

Abstract: A battery charger includes a plurality of rectifier, a plurality of switches respectively for the plurality of rectifier elements, a zero-crossing detector, a switch controller, and a detection reference changer. The plurality of rectifier elements rectify AC voltages of three phases output from a power generator. The plurality of rectifier elements, in an off-state, causes the plurality of rectifier elements to rectify the AC voltages to charge a battery. The plurality of rectifier elements, in an on-state, causes the AC voltages to be short-circuited to a negative side of the battery. The zero-crossing detector detects zero-crossings of the AC voltages. The switch controller outputs, based on the zero crossings, a gate signal for turning on and off the plurality of switches. The detection reference changer changes a reference for the zero-crossing detector to detect the zero crossings.

Abstract: A lighting circuit including a circuit for preventing erroneous illumination of LEDs wherein the lighting circuit, serving as a drive circuit for the LEDs, includes a transistor and a differential amplifier placed at a preceding stage of the transistor. A positive input side of the differential amplifier is connected to a battery through a switch and to a reference resistor Rref. A voltage of the battery is divided by resistors R1 and R2 and supplied to a negative input side of the differential amplifier. A resistance value (R1/R2)×Rref is set to be smaller than a leakage resistance value Rs of the switch. Thus, the differential amplifier is not turned on when the switch is opened even though there is a leakage at the switch. Therefore, the transistor is not turned on, and the LEDs are not illuminated.

Abstract: A lighting circuit including a circuit for preventing erroneous illumination of LEDs wherein the lighting circuit, serving as a drive circuit for the LEDs, includes a transistor and a differential amplifier placed at a preceding stage of the transistor. A positive input side of the differential amplifier is connected to a battery through a switch and to a reference resistor Rref. A voltage of the battery is divided by resistors R1 and R2 and supplied to a negative input side of the differential amplifier. A resistance value (R1/R2)×Rref is set to be smaller than a leakage resistance value Rs of the switch. Thus, the differential amplifier is not turned on when the switch is opened even though there is a leakage at the switch. Therefore, the transistor is not turned on, and the LEDs are not illuminated.

Abstract: The invention is to establish means of producing easily and at low cost “a coupled body of superconducting magnets”, comprised of multi-pole bulk superconducting magnets lined up such that the polarities thereof alternately vary so as to cause a magnetic field gradient to occur. The magnetizing method for producing a coupled body comprised of multi-pole bulk superconducting magnets with respective polarities varying comprises the steps of coupling adjacent members for bulk superconducting magnets of a plurality of members for bulk superconducting magnets with each other in such a way as to be freely superposable, foldable, and unfoldable, superposing all the members for the bulk superconducting magnets on top of one after another, and applying a magnetizing process thereto in as superposed state, and unfolding alternately and juxtaposing the respective bulk superconducting magnets as superposed after the magnetizing process as shown in FIG. 1(A) to FIG. 1(D).