Abstract: A telephone line monitoring device is connected to a telephone line and adjacent to a telephone device using the telephone line. The telephone line monitoring device includes a rectifying circuit for generating a corresponding direct current voltage according to an effective voltage of the telephone line; a first controller for generating a first control signal when the direct current voltage is lower than a predetermined voltage; a second controller for detecting an operating state of the telephone device and generating a second control signal when the telephone device is operated; a load booster for pulling down the effective voltage of the telephone line when enabled; and a first switch circuit for disabling the load booster whenever receiving the second control signal, and enabling the load booster when receiving the first control signal while not receiving the second control signal. A monitoring method and a telephone device are also provided.

Abstract: An illumination adjusting device for receiving power from a power supply and supplying output voltage to a lighting unit is provided herein. The illumination adjusting device includes a detector for detecting ambient illumination intensity and generating an ambient illumination value according to the ambient illumination intensity; a comparator for comparing the ambient illumination value with a predetermined value, the comparator outputting a first power signal when the ambient illumination value is lower than a predetermined value; an adjustor for adjusting the output voltage according to the first power signal, as a result, light emitted by the lighting unit is controlled within a predetermined illumination intensity range. A related illumination adjusting method is also provided.

Abstract: An apparatus for adjusting a sound volume includes an ultrasonic transreceiver for transmitting an ultrasonic signal and receiving a reflected ultrasonic signal reflected back from an object, and a volume module for adjusting the sound volume based on a time from transmitting the ultrasonic signal to receiving the reflected ultrasonic signal that has a different frequency from the ultrasonic signal.

Abstract: An interface circuit and an electronic device are used for expanding an output port of a micro processing unit. The interface circuit includes an input port electrically connected to the output port of the micro processing unit for receiving a control signals, and a plurality of output ports selectively driven to control external circuits by inputting different values of the control signal at the input port.

Abstract: A portable electronic device includes a player, a speaker, a control circuit, a switch circuit, and a current limiter. The player is for outputting analog audio signals. The speaker is for transforming the analog audio signals into sound. The control circuit is for generating a first control signal when ambient light intensity is lower than a predetermined value. The switch circuit is for turning on and transmitting the analog audio signals to the speaker when receiving the first control signal. The current limiter is for transmitting the analog audio signals to the speaker when the switch circuit turns off, and for limiting a current flowing through the speaker.

Abstract: An apparatus for protecting a password includes a keypad, a generator, and a processor. The keypad includes numeric keys for inputting a numeral and a display unit for displaying a random digit. The generator is coupled to the display unit for generating the random digit. The processor is configured for receiving the inputted numeral and calculating the password based on the inputted numeral and the random digit.

Abstract: An over-voltage protection circuit is provided herein for protecting a load from an over-voltage condition, and that does not cause a reverse voltage. The over-voltage protection circuit includes a first switch circuit and a second switch circuit. The first switch circuit is for outputting a switch-on signal when the input voltage is lower than or equal to a predetermined value and a switch-off signal when the input voltage is higher than the predetermined value. The second switch circuit for conducting the input voltage to the load when receiving the switch-on signal. An over-voltage protection method is also provided.

Abstract: A battery charging system for receiving an AC voltage and charging a rechargeable battery is provided herein. The battery charging system includes an adapter for rectifying an AC voltage into a first DC voltage; a controller for receiving a battery voltage of a rechargeable battery and outputting a control signal; and a DC switching convertor for converting the first DC voltage into a second DC voltage to recharge the rechargeable battery according to the control signal, wherein the second DC voltage changes according to the battery voltage. A charging method is also provided.

Abstract: A power-saving circuit is provided for saving electrical power by detecting a presence or absence of an object in a localized area. The power-saving circuit includes a sensor module, and a switch module connected to the sensor module. The detector is adapted for outputting a control signal at a first state when an object is detected in the localized area, and outputting a control signal at a second state when an object is detected not in the localized area. The switch module provides a stable DC voltage according to the control signal at the first state, and not provides the stable DC voltage according to the control signal at the second state.

Abstract: A projector for automatically adjusting images projected onto a screen comprises a detecting module for detecting the propagation time for the emitted ultrasonic wave sent by the projector to be echoed back by the screen as the reflected ultrasonic wave and received by the projector, a processing module for calculating a distance between the projector and the screen based on the propagation time, and outputting control signals, and an adjusting module for adjusting optical parameters of an optical module according to the control signals.

Abstract: A surveillance security system is used for selectively storing motion image data of an object to be detected. The surveillance security system includes an image-capturing device for capturing images from an object; a memory module for storing the image data; and a controller for controlling a storage process of the memory module. The controller includes a sampling module for taking a plurality of image frames from the image data; and a control-signal generating module for receiving the image frames and generating a write enable signal by comparing the image frames, wherein the write enable signal is used for controlling the storage process of the memory module. A surveillance security method for selectively storing motion image data of an object is also disclosed.