Abstract: A circuit for controlling rotation speed of a computer fan includes a fan connector providing for controlling the rotation speed of the computer fan, a rotation speed detector providing for detecting the rotation speed of the computer fan, a BIOS chip connected to the fan connector via the rotation speed detector and provided for receiving, and comparing rotation speed signals from the rotation speed detector, a super I/O chip connected to the BIOS chip and provided for outputting either a PWM signal or another PWM signal to be converted to a voltage signal to control rotation speed of the computer fan according to the result of the comparison, a integrated circuit connected to the super I/O chip and the fan connector and configured for converting the another PWM signal to an analog voltage signal.

Abstract: A network overclock control circuit for a computer includes an RC circuit, first and second comparator circuits, and first and second switch circuits. A signal pin of a network indicating lamp is connected to input terminals of the first and second comparator circuits via the RC circuit. Output terminals of the first and second comparator circuits are respectively connected to first and second clock pins of a clock chip via the first and second switch circuits. When network has little traffic, the first and second comparator circuits control the first and second switch circuits to output low level signals. When network has medium to high traffic, the first and second comparator circuits control the first and second switch circuits to output high and low level signals. When network is overloaded, the first and second comparator circuits control the first and second switch circuits to output high level signals.

Abstract: A sleep/awake circuit includes an infrared receiving/sending module, a micro-control circuit, and a bus control circuit. The micro-control circuit sends a command signal to the infrared receiving/sending module at predetermined intervals. The infrared receiving/sending module detects the presence or absence of a user and then sends a signal back to the micro-control circuit indicating a result. According to the result, the micro-control circuit exchanges data and clock signals with the bus control circuit. The bus control circuit then sends control signals to the computer to control sleep/awake states of the computer.

Abstract: A power supply circuit for a pulse width modulation controller includes a first resistor and an electric switch having first, second, and third terminals. The first terminal is capable of receiving a control signal of a computer. The second terminal is connected to a stand-by power supply of the computer. The third terminal is connected to the pulse width modulation controller via the first resistor.

Abstract: A method of measuring LED junction temperature includes the steps of: (a) obtaining a temperature curve of an LED; (b) inputting at least one rated AC voltage to the LED; (c) measuring a temperature at a specific point on an outer packaging structure of the LED, putting the temperature measured at the specific point into the temperature curve, and calculating a junction temperature of the LED by interpolation; and (d) substituting the result from the calculation in the step (c) into a numerical analysis model to obtain temperature oscillation of the LED.

Abstract: An exemplary power supply control circuit includes a first electric switch, a second electric switch, a third electric switch, a power supply, and an output terminal. The first electric switch has a first terminal connected to an SIO chip to receive a control signal. When the control signal is at a high level, the first electric switch is turned on, the second electric switch is turned off, the third electric switch is turned off, and the output terminal outputs no power supply. When the control signal is at a low level, the first electric switch is turned off, the second electric switch is turned on, the third electric switch is turned on, and the output terminal outputs the power supply.

Abstract: An exemplary power supply system and method for a motherboard includes a power circuit providing power for a south bridge, and a controller having first and second transistors. An input terminal of the power circuit is connected to a power supply. An output terminal of the power circuit is connected to a reset pin of the south bridge. A first terminal of the first transistor is configured for receiving a control signal from the south bridge. A second terminal of the first transistor is connected to a first terminal of the second transistor. A second terminal of the second transistor is connected to the reset pin of the south bridge. Each of the first and second transistors has a third terminal grounded.

Abstract: A start-up circuit which decreases a start-up current and stabilizes running of a DC fan. The start-up circuit includes a digital-analog converter for convert a digital control signal from a control chip to an analog control signal, a voltage sampling device connected to an output terminal of the digital-analog converter, a comparator, a switching device for controlling start-up of the DC fan, and a feedback device adjusting current passing through the switching device. The comparator includes two input terminals and an output terminal. One input terminal is connected to an output terminal of the voltage sampling device. The switching device is connected to the output terminal of the comparator. An output signal of the switching device is inputted to the other input terminal of the comparator via the feedback device.

Abstract: A circuit for controlling rotation speed of a computer fan includes a fan connector providing for controlling the rotation speed of the computer fan, a rotation speed detector providing for detecting the rotation speed of the computer fan, a BIOS chip connected to the fan connector via the rotation speed detector and provided for receiving, and comparing rotation speed signals from the rotation speed detector, a super I/O chip connected to the BIOS chip and provided for outputting either a PWM signal or another PWM signal to be converted to a voltage signal to control rotation speed of the computer fan according to the result of the comparison, a integrated circuit connected to the super I/O chip and the fan connector and configured for converting the another PWM signal to an analog voltage signal.

Abstract: A network overclock control circuit for a computer includes an RC circuit, first and second comparator circuits, and first and second switch circuits. A signal pin of a network indicating lamp is connected to input terminals of the first and second comparator circuits via the RC circuit. Output terminals of the first and second comparator circuits are respectively connected to first and second clock pins of a clock chip via the first and second switch circuits. When network has little traffic, the first and second comparator circuits control the first and second switch circuits to output low level signals. When network has medium to high traffic, the first and second comparator circuits control the first and second switch circuits to output high and low level signals. When network is overloaded, the first and second comparator circuits control the first and second switch circuits to output high level signals.

Abstract: An exemplary voltage regulating circuit for a motherboard includes a selecting switch and a first switch module, the selecting switch comprising a first input terminal arranged to receive a standby power provided by a power supply, a first control terminal arranged to receive a state signal from the motherboard via a first switch module controlled by a power good signal generated by the power supply, and an output terminal, wherein, when the motherboard is turned off, the state signal is at a high level and the first switch module is turned on by the power good signal for turning off the selecting switch to stop outputting the standby power.

Abstract: A power supply circuit for a motherboard includes a first resistor, a second resistor, a Schottky diode, and a direct current (DC) voltage source. The Schottky diode includes a first anode, a second anode, and a cathode. The first anode of the Schottky diode is respectively coupled to terminals of the first and second resistors, another terminal of each of the first and second resistors is respectively coupled to a power supply and ground. The second anode of the Schottky diode is coupled to the DC voltage source, the cathode of the Schottky diode is coupled to a south bridge.

Abstract: An apparatus for automatic testing of a PS/2 interface includes a micro controller unit, a PS/2 port, and a plurality of LEDs. The micro controller unit is coupled with both a data pin and a clock pin of the PS/2 interface. The LEDs coupled to the micro controller unit simulate functions of a keyboard. A related method for testing the PS/2 interface is also provided.

Abstract: An exemplary method for controlling rotation speed of a computer fan includes: judging the type of a fan by comparing two rotation speeds detected before and after changing a duty cycle of a PWM signal respectively; controlling the computer fan as a 4-pin fan the PWM signals if the rotation speeds are different; and controlling the computer fan as a 3-pin fan via voltage signals converted from the PWM signals if the rotation speeds are equal. And an exemplary circuit for controlling rotation speed of a computer fan is capable of controlling rotation speed of the 4-pin fan via PWM signals, and controlling rotation peed of the 3-pin fan via voltage signals converted from PWM signals.

Abstract: In one preferred embodiment, a power indicator circuit for a computer comprises a light-emitting diode (LED) indicating power management states of a computer; a first resister connected between one pole of the LED and a power source; a second resistor connected between the other pole of the LED and a power source, a first branch circuit connected between the one pole and ground; and a second branch circuit connected between the other pole and ground. Wherein the first resistor and the second resistor control a current through the LED. Because the LED emits lights of different colors or turns off according to the different power management states, it is easy for users to see what the power management state of the computer is.

Abstract: An exemplary PCI interface card includes a printed circuit board having a plurality of testing points arranged thereon, and a connecting portion configured to engage in a PCI connector of a motherboard. The connecting portion protrudes from the printed circuit board, and has a plurality of golden fingers disposed thereon. Some of the golden fingers configured to respectively connect with contacts of the PCI connector, which are set to connect with a south bridge chip of the motherboard to transmit address and data signals, are respectively electronically connected to the testing points of the printed circuit board.

Abstract: A pulse width modulation (PWM) generating circuit includes a first comparator, a first resistor, a second resistor, a third resistor, a fourth resistor, a capacitor, and a diode. The first resistor and the second resistor are connected in series between a voltage input and ground. The third resistor, the fourth resistor, and the capacitor are connected in series between the voltage input and ground. The first comparator has a non-inverting input connected to a node between the first resistor and the second resistor, an inverting input connected to a node between the fourth resistor and the capacitor, and an output connected to a node between the third resistor and the fourth resistor. The diode is connected between the non-inverting input and the output. The inverting input of the first comparator provides triangular wave signals to a second comparator by which PWM signals are generated.

Abstract: A sleep/awake circuit includes an infrared receiving/sending module, a micro-control circuit, and a bus control circuit. The micro-control circuit sends a command signal to the infrared receiving/sending module at predetermined intervals. The infrared receiving/sending module detects the presence or absence of a user and then sends a signal back to the micro-control circuit indicating a result. According to the result, the micro-control circuit exchanges data and clock signals with the bus control circuit. The bus control circuit then sends control signals to the computer to control sleep/awake states of the computer.

Abstract: In one preferred embodiment, a power indicator circuit for a computer comprises a light-emitting diode (LED) indicating power management states of a computer; a first resister connected between one pole of the LED and a power source; a second resistor connected between the other pole of the LED and a power source, a first branch circuit connected between the one pole and ground; and a second branch circuit connected between the other pole and ground. Wherein the first resistor and the second resistor control a current through the LED. Because the LED emits lights of different colors or turns off according to the different power management states, it is easy for users to see what the power management state of the computer is.

Abstract: A self-startup circuit for a DC fan includes a voltage sampling device receiving a first control signal, a comparator, and a self-startup device. The comparator includes two input terminals and an output terminal. One input terminal is connected to an output terminal of the voltage sampling device. The self-startup device has a switching device and a diode connected in parallel. The self-startup device has an input terminal connected to the output terminal of the comparator, and outputs a second control signal for keeping the DC fan rotating even when the first control signal has a very low duty cycle.