Abstract: A driver device includes a circuit board, a number of sockets, a number of driver chips, a control switch, and a signal output element. The sockets are positioned on the circuit board. Each driver chip is received in and electrically connected to a corresponding socket. The control switch includes a number of switches. An input of each switch is electrically connected to a corresponding socket. An output of each switch is electrically connected to the computer motherboard through the signal output element.

Abstract: A linear voltage stabilizing circuit includes a main stabilizing unit, a first resistor, a second resistor, and a sub-stabilizing unit. The main stabilizing unit includes a first transistor connected between a signal input terminal and a signal output terminal, and a first comparator controlling the first transistor. The first and the second resistor are connected between the signal input terminal and ground. The voltage between the first resistor and the second resistor is equal to a first reference voltage. The sub-stabilizing unit includes a third resistor, a fourth resistor, a second transistor connected between the signal input terminal and the first transistor, and a second comparator. The third and fourth resistor are connected between the second comparator and ground. The node of the third and fourth resistor is connected to the node between the first and the second resistor. The second comparator controls the second transistor turn on or off.

Abstract: A printed circuit board includes a reference layer configured to connect to a power or a ground and a dielectric layer stacked on the reference layer. The dielectric layer includes a component surface opposing the reference layer. The component surface forms a differential pairs, a protection runner, and a power runner. The differential pairs include a substantially linear part. The protection runner is intervened between the linear part and the power runner, and is substantially parallel to the differential pairs. The length of the protection runner is approximately equal to that of the linear part. Each of the two ends of the protection runner forms a via that electrically connects the protection runner to the reference layer.

Abstract: An electronic device includes a power unit, an alarm, a silicon-controlled rectifier (SCR), a thermo-sensor, a variable resistor, and a zener diode. The variable resistor is connected to the thermo-sensor in series between the power unit and ground. A first input terminal of the comparator is connected to a node between the thermistor and the variable resistor. A second input terminal of the comparator is connected to a node between the zener diode and the first resistor to receive a reference voltage. An output terminal of the comparator is connected to a control terminal of the SCR. When a temperature of the electronic device is higher than a predetermined temperature, the comparator turns on the SCR to activate the alarm. When the temperature of the electronic device is lower than the predetermined temperature, the comparator turns off the SCR and the alarm turns off.

Abstract: A circuit is for checking the voltage of a battery. The circuit includes a regulator component, a pnp type transistor, an npn transistor, a diode, and an alarm. The circuit activates an alarm when the voltage of the battery is less than a preset value.

Abstract: A computer system on/off test apparatus includes a parameter setting and test control circuit, a test indicating circuit, a voltage converting circuit, and an on/off signal switch circuit. The parameter setting and test control circuit includes a micro control unit (MCU) to set a number of test times and control an on/off test of a motherboard. The test indicating circuit is operable to display the number set by the parameter setting and test control circuit, and display a successful number of test times of the on/off test. The voltage converting circuit is operable to convert a first voltage received from a first standby power connector to a second voltage. The on/off signal switch circuit is operable to switch the first and second voltages according the control by the MCU.

Abstract: A low voltage warning circuit includes an input terminal configured to receive a supply voltage, a reference voltage connected to the input terminal for providing a reference voltage, a transistor connected to the reference voltage circuit and the input terminal, and a silicon controlled rectifier connected to the transistor and the input terminal via a indicating device, the low voltage warning circuit raise a warning through the indicating device when the supply voltage is below the reference voltage.

Abstract: A regulating system includes an input port having a first input terminal and a second input terminal, an output port having a first output terminal and a second output terminal, a regulating circuit, an over-current protection circuit, and an overvoltage protection circuit. The overvoltage protection circuit includes a regulating diode, a first bipolar transistor and a second bipolar transistor. The first output terminal is connected to the base of the first bipolar transistor via the regulating diode and grounded via first bipolar transistor. A base of the second bipolar transistor connects to the collector of the first bipolar transistor. The second output terminal is grounded via the second transistor. When an output voltage of the first output terminal increases over a predetermined voltage, an electrical connection between the second output terminal and ground is cut off to stop providing output voltage from the output port.

Abstract: The lighting delay circuit can keep a light being on for a predetermined time then turn off the light. The circuit comprises a thermistor to sense temperature around the light when the light is on, an electronic switch controlled by the thermistor, and a relay controlled by the electronic switch to turn off the light when the electronic switch is turned on.

Abstract: A fan circuit controls a speed of a fan. A control chip outputs a pulse width modulation (PWM) signal that changes with the temperature of an electronic device that the fan is mounted in. An input circuit converts the PWM signal into a continual voltage signal. An amplifier circuit amplifies the voltage signal and outputs a control signal. When the control signal is less than a threshold voltage, the control circuit is turned on and the fan receives current which is less than preset current. When the control signal is greater than the threshold voltage, the control circuit is turned off and the fan receives current which is greater than the preset current.

Abstract: A circuit for controlling a rotation speed of a fan of an electronic device according to a temperature of the electronic device. The circuit senses the temperature of the electronic device, and outputs a voltage changing with the sensed temperature. The rotation speed of the fan changes with the voltage. The circuit slows the rotation speed of the fan down when the sensed temperature of the electronic device is decreased.

Abstract: A fan control system includes a temperature detecting circuit and a rotation rate control circuit. The detecting circuit includes a first amplifier, a second amplifier, and a thermistor. The rotation rate control circuit includes a first terminal, a second terminal, and a third terminal. The detecting circuit detects temperature and outputs a voltage signal. The rotation rate control circuit receives the voltage signal and controls the rotation rate of the fan according to the voltage signal.

Abstract: A fan control system includes a temperature detecting circuit and a rotation rate control circuit. The detecting circuit includes a first amplifier, a second amplifier, and a thermistor. The rotation rate control circuit includes a first terminal, a second terminal, and a third terminal. The detecting circuit detects temperature and outputs a voltage signal. The rotation rate control circuit receives the voltage signal and controls the rotation rate of the fan according to the voltage signal.

Abstract: A fan speed control circuit includes a voltage input terminal, a thyristor, a thermistor, and first and second switches. The terminal is grounded through a first resistor and the thermistor, connected to an anode of the thyristor, and connected to a second terminal of the second switch through a second resistor. A node between the resistor and the thermistor is connected to a control terminal of the first switch. A second terminal of the first switch is grounded. A first terminal of the first switch is connected to a control terminal of the thyristor through a third resistor. A fourth resistor is connected between the anode and control terminal of the thyristor. A control terminal of the second switch is connected to the control terminal of the thyristor. A first terminal of the second switch is connected to a cathode of the thyristor and a voltage pin of a fan.

Abstract: A temperature monitoring circuit includes a negative temperature coefficient (NTC) resistor, a zener diode, an alarm, a silicon controlled rectifier. A first terminal of the NTC resistor is connected to a power supply through a first resistor. A second terminal of the NTC resistor is grounded. A cathode of the zener diode is connected to a node between the NTC resistor and the first resistor. An anode is grounded through a second resistor. A first terminal of the alarm is connected to the cathode of the zener diode, and is grounded through a third and fourth resistors in series. A cathode of the silicon controlled rectifier is connected to the anode of the zener diode. An anode of the silicon controlled rectifier is connected to a second terminal of the alarm. A control terminal of the silicon controlled rectifier is connected to a node between the third and fourth resistors.

Abstract: An under-voltage warning circuit includes a Zener diode, a transistor, an annunciator, and a thyristor. When the power source is within a certain range, the annunciator does not work. When the voltage level of the power source V_in is lower than the predetermined value, the annunciator works to denote that the power source is under-voltage.

Abstract: A system and method for testing a computer divide test programs in a test file into hardware test programs and software test programs. A test server selects one or more test programs from the divided test file according to test parameters of the computer. The test server generates a test command for testing test items of the computer. The computer executes the test command. The test server analyzes test results and stores analyzed results into a predefined storage path.

Abstract: A voltage stabilizing circuit including an input port, an output port, a transistor, a diode, a three-terminal voltage regulating reference source, a first resistor, and a second resistor. The transistor has a collector terminal and an emitter terminal connected to the input port and the output port, respectively. The diode has an anode connected to the input port and a base terminal of the transistor. The three-terminal voltage regulating reference source has an anode connected to ground, a cathode connected to the input port and a cathode of the diode, and a reference terminal The first resistor is connected between the cathode of the diode and the reference terminal of the three-terminal voltage regulating reference source. The second resistor is connected between ground and the reference terminal of the three-terminal voltage regulating reference source.

Abstract: An auto-shut off circuit includes a relay, a voltage conversion device, a first diode, a second diode, a third diode, a capacitor, a first transistor, and a second transistor. The relay includes a coil and a switch. The auto-shut off circuit disconnects an electronic device from a power supply when the electronic device is not at a working state.

Abstract: A voltage detection circuit used to detect a voltage source includes a Zener diode, a thyristor, a first resistor, a second resistor, a first light-emitting diode (LED), and a second LED. A cathode of the Zener diode is connected to the voltage source. An anode of the Zener diode is connected to a control terminal of the thyristor through a first resistor. An anode of the thyristor is connected to the voltage source through a second resistor. The anode of the thyristor is connected to an anode of the first LED. A cathode of the thyristor is connected to a cathode of the first LED. The cathode of the thyristor is connected to an anode of the second LED, and a cathode of the second LED is grounded.