Abstract: A DC power supply control system includes a voltage conversion module configured to couple to a DC power supply and convert a DC voltage to a power voltage; a power port coupled to the voltage conversion module and configured to be coupled to a peripheral load; a switch module coupled to the voltage conversion module and configured to switch on/off the voltage conversion module; and a detection module coupled to the power port and configured to detect the peripheral load. When the detection module detects the peripheral load, the switch module switches on the voltage conversion module, allowing the DC voltage to be converted to the power voltage. Without a peripheral load being detected by the detection module, the switch module switches off the voltage conversion module. A DC power supply control circuit is further disclosed.

Abstract: A rotational speed control system includes a fan controller and a fan controlling circuit. The fan controlling circuit is coupled to the fan controller. The fan controlling circuit can receive a rotational speed control signal and output a fan driving signal to the fan controller. The fan driving signal is a regulated high level voltage signal. The fan controller can adjust rotational speed of the fan according to the driving signal.

Abstract: A rotational speed control system includes a fan controller and a fan controlling circuit. The fan controlling circuit is coupled to the fan controller. The fan controlling circuit can receive a rotational speed control signal and output a fan driving signal to the fan controller. The fan driving signal is a regulated high level voltage signal. The fan controller can adjust rotational speed of the fan according to the driving signal.

Abstract: A fan detecting device includes a motherboard, a first direct voltage, and an insert detecting unit. The motherboard includes a fan socket unit. The fan socket unit includes an insert detecting pin. The insert detecting unit includes a detecting terminal. The insert detecting pin is coupled to the first direct voltage and the detecting terminal. When the fan socket unit is void, the detecting terminal receives a high level signal. When the fan socket unit is coupled to a fan connector, the insert detecting pin is grounded; the detecting terminal receives a low level signal.

Abstract: A DC power supply control system includes a voltage conversion module configured to couple to a DC power supply and convert a DC voltage to a power voltage; a power port coupled to the voltage conversion module and configured to be coupled to a peripheral load; a switch module coupled to the voltage conversion module and configured to switch on/off the voltage conversion module; and a detection module coupled to the power port and configured to detect the peripheral load. When the detection module detects the peripheral load, the switch module switches on the voltage conversion module, allowing the DC voltage to be converted to the power voltage. Without a peripheral load being detected by the detection module, the switch module switches off the voltage conversion module. A DC power supply control circuit is further disclosed.

Abstract: A motherboard applied in an electronic device includes a platform controller hub (PCH), a basic input and output system (BIOS), and a control circuit. The BIOS compares a temperature of the motherboard with a preset temperature in the BIOS, and controls the PCH to output a first control signal or a second control signal, according to a determined value. The control circuit controls a fan to operate or not operate, according to the first control signal or the second control signal. When the temperature of the motherboard is greater than the preset temperature, the fan starts operating. Therefore, the motherboard can save energy.

Abstract: A power supply circuit includes an input circuit and a switch circuit. The switch circuit includes a first switch and a second switch. The input circuit receives a first DC voltage. A first terminal of the first switch receives a control signal. A second terminal of the first switch is grounded. A third terminal of the first switch is electrically coupled to a first terminal of the second switch. A second terminal of the second switch outputs a second DC voltage. A third terminal of the second switch is electrically coupled to the input circuit. When the second DC voltage is overvoltage, the first switch receives the control signal and turns off, the second switch turns off, the second terminal and the third terminal of the second switch are cut off, and the second terminal of the second switch can not output the second DC voltage.

Abstract: A printed circuit board which avoids the melding of closely adjacent solders includes a top surface, a number of electronic elements and a number of solders. The top surface includes a plurality of copper clad areas. Each copper clad area includes a head area and a neck area. The neck area is positioned on same side of the head area. The neck area includes two edges extended from a fringe of the head area and a terminal point. The two edges intersect at the terminal point. The electronic elements are positioned at the head area. Each solder includes a soldering portion and a tip portion. The soldering portion is attached on the head area and surrounds the electronic element. The tip portion is attached on the neck area. A fringe of the solder is same as the fringe of the copper clad area.