Abstract: A measurement card includes a circuit board, an edge connector on a bottom edge of the circuit board, a port arranged on the circuit board, and a single-pole double-throw switch for connecting the port to either a first or a second pin of the edge connector to tests the VDDQ and VTT outputs of a memory slot.

Abstract: A buck converter includes a power supply unit, two MOSFETs and a delay circuit. The PWM module is coupled to the gates of the two MOSFETs to alternatively turn on the two MOSFETs. The delay circuit is coupled between an output terminal and an input node of the PWM module for making sure that a voltage applied to the PWM module is after a voltage applied to a drain the MOSFETs.

Abstract: A multimeter includes a main body, two probes extending from the main body, a battery unit arranged in the main body, and a charging system arranged in the main body and configured for charging the battery. The charging system includes a microcontroller with an external input voltage sampling circuit, a battery voltage sampling circuit and a voltage regulator circuit each electrically connected the microcontroller. The microcontroller compares sampled signals from the external input voltage sampling circuit and the battery voltage sampling circuit, and controls the voltage regulator circuit to regulate the external input voltage to be applicable to the battery based on the comparison.

Abstract: A power measuring system for measuring a turning-on power, a turning-off power, and a turned-on power of a first field-effect transistor includes a pulse driver, a first resistor, a processing unit, and an indication unit. The pulse driver generates square wave signals. The processing unit samples voltages at the source and the drain of the first field-effect transistor, and at the first and second terminals of the first resistor at the moment when the square wave signals changes from low to high or from high to low, and calculates the turning-on power, the turning-off power, and the turned-on power of the first field-effect transistor. The indication unit displays the turning-on power, the turning-off power, and the turned-on power of the first field-effect transistor.

Abstract: A balancing resistor testing apparatus is configured for acquiring a resistance of a balancing resistor electronically connected to a supercapacitor of a series supercapacitor assembly in parallel. The balancing resistor testing apparatus includes a controller and a digital potentiometer. The controller detects a voltage across each supercapacitor of the series supercapacitor. The digital potentiometer comprising a plurality of variable resistors each of which is electronically connected to a supercapacitor in parallel, the controller controls the digital potentiometer to continuously adjust the effective resistance of each potentiometer until the controller detects that each supercapacitor has the same or very similar voltage.

Abstract: A resistance determining system for an over voltage protection (OVP) circuit, includes an external power source, a microcontroller, a digital rheostat and a display unit. The external power source supplies an external voltage to the OVP circuit. The microcontroller stores an over voltage value. The microcontroller is connected to the external power source and configured to detect the external voltage and compare the external voltage with the over voltage value. The digital rheostat is connected to the microcontroller and includes a first rheostat having two connection terminals respectively connected to two first connection ends of the OVP circuit. The microcontroller adjusts the first rheostat to be a first resistance value to activate the OVP circuit when the external voltage is substantially equal to the over voltage value. The display unit is connected to the microcontroller and configured to display the first resistance value.

Abstract: A circuit for alarming abnormal state of a computer fan includes a detection circuit coupled to the computer fan, a controller coupled to the detection circuit and the computer fan, an alarm unit coupled to the controller. The detection circuit detects a power source and a speed control signal received by the computer fan, the controller determines the work state of the computer fan according to the power source, the speed control signal, and a speed signal received from the computer fan and raises an alarm through the alarm unit if the computer fan is not working normally.

Abstract: A detection device to detect a power serving time of a super capacitor for a power-disconnected storage card and an amount of the data packets capable of being stored during the detected serving time is provided. The power-disconnected storage card includes a memory. The detection device includes a power supply unit, the super capacitor, a controller, a storage unit, and a detection unit. The storage unit stores the data packets. The detection unit includes a charge notification module, a data notification module and a time module. The charge notification module generates a first notification signal to the time module. The data notification module generates a second notification signal to the time module when the storage unit transmits the data packet to the memory. The time module records time when the memory completely store the data packet according to the first notification signal and the second notification signal.

Abstract: A security system and method for an electronic device include comparing data in a Subscriber Identity Module (SIM) card with data in a virtual SIM card, if the virtual SIM card is not blank. The security system further include determining whether the electronic device has received a command of reporting loss of the SIM card from the network server, if the data in the SIM card is the same as the data in the virtual SIM card. The security method further includes running the electronic device normally if the electronic device has not received the command of reporting loss of the SIM card. If the command of reporting loss is received, a contact list and message of the electronic device are deleted and a calling function of the electronic device is disabled.

Abstract: A computer memory device includes a circuit board, a number of chips mounted on a surface of the circuit board, and an edge connector set on a bottom side of the circuit board. The edge connector includes ground pins, power pins, and data pins. Top ends of the ground pins, the power pins, and the data pins are in alignment with one another. Each ground pin is longer than each of the power pins and the data pins.

Abstract: A power cable is configured for connecting at least one electrical device to a power source. The power cable includes an input terminal, at least one output terminal, a power transmitting wire, a switch, a voltage setting device, a voltage sampling device, a voltage comparing device and a power supply. The power transmitting wire connects the input terminal and the output terminal via the switch. The voltage sampling device is configured for sensing a voltage of the output terminal. The voltage comparing device is configured for comparing a preset voltage stored in the voltage setting device and the sampled voltage sensed by the voltage sampling device to turn on or turn off the switch according to the compared result. The power supply is configured for reducing the voltage of the power source to the rated voltage of the voltage comparing device to power the voltage comparing device.

Abstract: A keyboard includes a number of first keys, a control circuit, a switch circuit, and a second key. The switch circuit includes a number of switches. The second key is connected to first terminals of two switches of the switch circuit via the control circuit. A second terminal of each of the switches is connected to a first key. When a second key is pressed, the control circuit controls the switches corresponding to the pressed second key to be turned on, to activate the first keys which are connected to the switches.

Abstract: A power supply circuit includes a pulse width modulation (PWM) chip, a number of phase circuits, a voltage output end, and a spike suppression circuit. The spike suppression circuit is connected to each of the phase circuits and the voltage output end. The PWM chip controls all of the phase circuits to alternately output power supply voltages according to a predetermined sequence. The spike suppression circuit receives the power supply voltages, and filters out voltage spikes in the power supply voltages, thereby outputting steady voltages to the voltage output end.

Abstract: A wireless unlocking system includes a programmable telephone. When the programmable telephone receives a call from a communication terminal along with a calling telephone number, the calling telephone number is matched with a number of pre-stored telephone numbers. The programmable telephone transmits an unlocking signal to an electrically controlled lock and unlocks a door if the telephone number of the call successfully matches one of the pre-stored telephone numbers.

Abstract: An output voltage adjustment circuit for buck circuits includes a microcontroller, first to eighth keys, and a display unit. The first to eighth keys input voltage adjustment signals to the microcontroller. A first input pin of the microcontroller is connected to a voltage output terminal. A second resistor is connected between the first input pin of the microcontroller and ground. A first to a sixth input/output pin of the microcontroller are connected to the display unit. A first to an eighth output pin of the microcontroller are connected to a pulse width modulation (PWM) controller. The first to eighth keys are selectively activated to provide voltage adjustment signals to the microcontroller, sampling output voltages of the voltage output terminal, comparing with a predetermined voltage, controlling the PWM controller to fine tune the duty cycle to output a stable voltage from the voltage output terminal. The display unit displays the voltages on the voltage output terminal.

Abstract: A circuit for measuring the DC resistance of an inductor includes an input unit, a microprocessor module, a current source and a voltage detecting unit. The microprocessor module receives signals from the input unit and generates different signals to command constant currents through the inductor by the current source. The voltage detecting unit reads voltages of the inductor and outputs the voltages obtained to the microprocessor module. According to the currents and the voltages read, the microprocessor module may calculate the DC resistance(s) of the inductor.

Abstract: A sequence control circuit for power sources includes two switched circuits and a sequence control unit. Each of the switched circuits has a control node and is coupled between a power source and a load. The sequence control unit includes two output terminals coupled to the control nodes. The output terminals generate control signals to control the sequence of the circuits being turned on.

Abstract: A power circuit which is applicable to a data storage device. A boost circuit receives a first voltage and converts it to a second voltage. A charging and discharging circuit receives the second voltage and charges a charging capacitor. As long as a voltage detecting circuit detects that the second voltage exists, it outputs a first selection signal. When the voltage detecting circuit detects that the second voltage does not exist, it outputs a second selection signal and also outputs a signal to the charging and discharging circuit, to release a stored voltage. A voltage selection circuit will output the second voltage according to the first selection signal, or will output the stored voltage from the charging capacitor according to the second selection signal. Buck circuits convert the second voltage or the stored voltage to the different voltages required by a control chip of the data storage device.

Abstract: A wireless unlocking system includes a programmable telephone. When the programmable telephone receives a call from a communication terminal along with a calling telephone number, the calling telephone number is matched with a number of pre-stored telephone numbers. The programmable telephone transmits an unlocking signal to an electrically controlled lock and unlocks a door if the telephone number of the call successfully matches one of the pre-stored telephone numbers.

Abstract: An input power measuring device includes a board with an edge connector, a first dual inline memory modules (DIMM) socket, a resistor, a differential amplifier circuit, a voltage dividing circuit, a display screen, and a controller. When the edge connector is inserted into a second DIMM socket of a motherboard and the motherboard is powered on, the resistor samples first current, and converts the first current into a first voltage. The differential amplifier circuit amplifiers the first current to a second current. The voltage dividing circuit divides the first voltage, and outputs a second voltage. The controller converts the second current into a third current, converts the second voltage into a third voltage, and calculates a power according to the third current and the third voltage.