Abstract: A device for testing capacitive loads of a power supply includes a controller, a power supply switching circuit, a capacitive load switching circuit, and a current sampling circuit. The power supply switching circuit selects one of output voltages of the power supply to be electronically connected to the capacitive load switching circuit and the current sampling circuit. The current sampling circuit samples an output current of one output of the power supply selected by the controller. The controller turns on and off switches of the capacitive load switching circuit for matching an output current of the power supply with a reference current until the output current equals to the reference current. The controller outputs a total magnitude of the capacitive loads.

Abstract: A resistance determining system and method for a protection circuit, includes a resistance determining unit. The resistance determining unit interconnects a microcontroller and a digital resistor, where the microcontroller has first setting voltage corresponding to a first voltage threshold for activating the protection circuit, and the microcontroller is capable of receiving and converting a first external voltage input to the protection circuit to be a first converted voltage. The digital resistor includes a first variable resistor having two terminals connected to the respective first terminal and the second terminal. The microcontroller adjusts a resistance of the first variable resistor to be a first threshold resistance if the first converted voltage is substantially equal to the first voltage threshold, and the first resistance is determined to be substantially equal to the first threshold resistance.

Abstract: A power supply control circuit includes a main controller, a current detection unit electronically connected to the main controller, and a mode switch unit electronically connected to the main controller. The current detection unit cooperates with the main controller in detecting a value of an output current of a power supply circuit. The main controller determines whether the power supply circuit is operating in a discontinuous conduction mode or in a continuous conduction mode according to the value of the output current of the power supply circuit, and controls the mode switch unit to switch the power supply circuit to the continuous conduction mode when the power supply circuit operates in the discontinuous conduction mode.

Abstract: A snubber circuit for decreasing a voltage spike of a buck converter includes a resistor unit, a capacitor unit, a detecting unit, and a control unit. The resistor unit provides multiple groups of resistance values. The capacitor unit provides multiple groups of capacitance values. The detecting unit detects voltage spikes of the buck converter corresponding to each group of resistance values and capacitance values. The control unit selects each group of resistance and capacitance to respectively connect to the buck converter and determines a group of resistance and capacitance corresponding to a lowest voltage spike by comparing the detected voltage spikes with each other.

Abstract: An RC test circuit includes an RC circuit, a digital rheostat, a control chip, and an oscillograph. The RC circuit includes a plurality of positive terminals and a plurality of negative terminals. The digital rheostat includes a plurality of rheostats each including a sliding terminal and a fixed terminal. The sliding terminals are correspondingly connected to the positive terminals while the fixed terminals are correspondingly connected to the negative terminals. The control chip is connected to the digital rheostat, and configured for controlling the digital rheostat to change the resistance of each rheostat. The oscillograph is connected to the RC circuit for displaying a waveform of the RC circuit.

Abstract: A protocol resolution device electrically connected to a central processing unit (CPU) includes a signal controller to receive communication protocol from the CPU, a signal input module, and display module. The signal input module provides an electrical signal to the signal controller. The signal controller decodes the communication protocol from the CPU and stores the decoded communication protocol, the signal controller selectively accesses and calls up the decoded communication protocol according to the electrical signal, and transmits the decoded communication protocol to the display module for display.

Abstract: A power supply conversion circuit includes a PWM chip and many sub-circuits. Each sub-circuit includes an inductor, a first capacitor connected to ground, a first resistor connected in series with the first capacitor to form a branch parallel to the inductor, a differential pair having a first differential signal trace and a second differential signal trace, a second resistor, and a second capacitor. The first trace is connected between the connection of the first resistor and the first capacitor and the PWM chip. The second resistor is connected between the connection of the first resistor and the inductor and the second capacitor. The second trace is connected between the connection of the second resistor and the second capacitor and the PWM chip. The ratios of the capacitances of each two second capacitors are the same as that of the lengths of the traces of each two corresponding differential pairs.

Abstract: A measuring device for a hard disk drive includes a first input node, a hard disk drive having a first input terminal, the first input terminal being coupled to the first input node to provide power to the hard disk drive. A first input current sampling unit is coupled between the first input node and the first input terminal of the hard disk drive to obtain a first input current Iin1. A first input voltage sampling unit is coupled to the first input terminal of the hard disk drive to obtain a first input voltage Uin1. A control unit is coupled to the first input current sampling unit and the first input voltage sampling unit to receive the first input current and the first input voltage.

Abstract: A measuring circuit includes a voltage converting circuit, a discharging and sampling circuit, a control circuit, and a charging circuit. The voltage converting circuit converts a voltage to a working voltage and outputs the working voltage to the discharging and sampling circuit. The charging circuit charges a capacitor and outputs a stop charging signal to the control circuit. The control circuit includes a microprocessor with a timer, to output a discharging control signal to the discharging and sampling circuit for controlling the capacitor to discharge according to the stop charging signal. The discharging and sampling circuit includes a discharging resistor, and measures voltages of the capacitor and the discharging resistor. The microprocessor obtains a discharging time of the capacitor for calculating a capacitance of the capacitor, and obtains the voltages of the capacitor and the discharging resistor for calculating a parasitic resistance of the capacitor.

Abstract: A server rack includes a main body, an electronic scale, and an alarm. The main body is used for receiving a number of servers. The electronic scale includes a pressure sensor and a microcontroller. The main body presses on the pressure sensor so that the pressure sensor can measure the pressure from the main body to obtain a pressure signal. The microcontroller analyzes the pressure signal to calculating the total weight of the main body and the servers. The alarm stores a predetermined weight threshold, which is the total weight of the main body and the maximum servers that the main body can bear. The alarm also compares the measured total weight with the predetermined weight threshold. When the measured total weight is larger than the predetermined weight threshold, the alarm alarms.

Abstract: An exemplary infrared control system includes an infrared control unit and a computer. The infrared control unit is capable of transmitting an infrared signal. The computer includes an infrared response unit, and the infrared response unit includes an infrared receiving circuit and a control circuit electrically connected to the infrared receiving circuit. The infrared receiving circuit is capable of receiving the infrared signal from the infrared control unit. Accordingly the control circuit is capable of processing the infrared signal from the infrared receiving circuit to generate a corresponding command signal to control the computer to power on/off or reset.

Abstract: A motor control circuit for controlling rotation directions of a motor includes a primary power supply, a voltage monitor unit, a motor driving chip, a controller and a backup power supply. The backup power supply is constantly charged by the primary power supply when the primary power supply is in service. The voltage monitor unit is electronically connected to the primary power supply, and is configured for determining whether the primary power supply is in or out of service. The controller controls the motor driving chip to drive the motor to rotate in a first direction when the primary power supply is in service, and alternatively controlling the motor driving chip to drive the motor to rotate in a second direction reverse to the first direction when the primary power supply is out of service.

Abstract: An exemplary motor control circuit for controlling a motor includes a motor driving chip, a sensing unit, and a controller. The motor driving chip motor driving chip is electronically connected to the motor. The sensing unit includes a proximity sensor, the proximity sensor detects whether an external object is proximate to the proximity sensor. The controller is electronically connected to the motor driving chip and the sensing unit, the controller controls the motor driving chip to drive the motor to rotate in a first direction when an external object is detected, and controls the motor driving chip to drive the motor to rotate in a second direction reverse to the first direction when no external object is detected for a predetermined period of time.

Abstract: A measurement circuit includes a switch unit with a number of keys selectively pressed to output different resistance regulating signals. A resistance setting circuit receives the resistance regulating signals and connects different resistances to a control circuit. The control circuit obtains a voltage according to the chosen resistance by the resistance setting circuit and compares the voltage with a preset voltage. If the voltage is greater than the preset voltage, the control circuit outputs a high level signal to a control pin of a pulse width modulation (PWM) controller, to control a voltage unit to output a voltage. If the voltage is less than the preset voltage, the control circuit outputs a low level signal to the control pin of the PWM controller, to control the voltage unit to not output a voltage. A display unit displays the chosen resistance.

Abstract: A measurement circuit includes a switch unit with a number of keys selectively pressed to output different resistance regulating signals. A resistance setting circuit receives the resistance regulating signals and connects different resistances to a voltage circuit and a current circuit. The voltage circuit outputs different voltages. The current voltage receives a voltage from the voltage circuit and outputs a current to a capacitor. A detecting circuit measures a temperature of the capacitor and outputs the temperature to the resistance setting circuit. The resistance setting circuit compares the received temperature with a preset temperature. If the received temperature is equal to or greater than the preset temperature, the resistance setting circuit outputs short-circuit information of the capacitor. If the received temperature is less than the preset temperature, the resistance setting circuit outputs normal information of the capacitor. A display unit displays the information of the capacitor.

Abstract: An exemplary electronic load includes a simulation load, a comparison circuit, a sample resistor, and a voltage control circuit. The comparison circuit includes a comparator. The sample resistor samples current flowing through the simulation load, and outputs the sampled current to a negative input of the comparator. An output of the comparator is connected to the simulation load. The voltage control circuit outputs an adjustable control voltage to a positive input of the comparator to control the simulation load to output an adjustable current.

Abstract: An electrical parameter detection device is configured for detecting electrical parameters of a peripheral component interconnect (PCI) connector including a plurality of power pins. The electrical parameter detection device includes a processor module, a first detection module, and a second detection module. The processor module continuously detects voltage values of electric potentials provided by each of the power pins of the PCI connector using the first detection module, and determines time sequences of the electric potentials according to the voltage values of the electric potentials. Furthermore, the processor module detects the amount of power provided by each of the power pins of the PCI connector using the second detection module.

Abstract: A voltage regulating device includes a connector, a slot, a voltage regulating circuit, and a control module. The connector is obtains an initial voltage from an external power supply. The slot is configured for electrically connecting to a load. The voltage regulating circuit is connected between the connector and the slot. In accordance with user input into a keyboard connected to a control microchip as to a voltage level required, the voltage regulating circuit converts the initial voltage to a required test voltage and outputs the required test voltage to the load by the slot. The control microchip controls the voltage regulating circuit to convert the initial voltage into the required test voltage.

Abstract: A power supply device is configured for supplying electrical power to a central processing unit (CPU) of an electronic device. The CPU operates in a number of working modes. The power supply device includes a power supply module operating in a number of power supply modules corresponding to the working modes of the CPU, a number of compensation circuits respectively corresponding to the power supply modes, and a control module. The control module determines the working mode of the CPU and controls the corresponding compensation circuit to electrically connect to the power supply module to provide a loop compensation to the power supply module which improves stability and responding speed of the power supply module.

Abstract: A capacitance measurement circuit includes a charge module to charge a capacitor, a discharge module to hold the capacitor discharge at a constant current, and a control module. The control module includes a timer, a detecting sub-module, a trigger sub-module, and a computing sub-module. The detecting sub-module detects whether the capacitance is fully charged and detects voltages V and discharge current I when the capacitor discharges. The trigger sub-module triggers the charge module to stop charging the capacitor and triggers the timer starts to time a preset discharge time once the capacitor is fully charged. The computing sub-module computes any output voltage differences during the discharge time, and further computes the capacitance value of the capacitor.