Abstract: The invention provides a mobile power bank for charging a portable electronic device. The mobile power bank includes a casing, a printed circuit board disposed in the casing, a rechargeable battery disposed in the casing and electrically connecting to the printed circuit board, a curly transmission wire, and an adapter tip. The curly transmission wire passes through the casing and electrically connects to the rechargeable battery via the printed circuit board. The adapter tip is coupled to the curly transmission wire and electrically connecting to the portable electronic device.

Abstract: An alterable battery charger for charging a rechargeable battery is disclosed. The alterable battery charger includes a clamp for clamping the rechargeable battery, a first interface disposed on the clamp to connect to an external power, and two conductive pieces disposed in the clamp. At least one of the conductive pieces is pivoted on the clamp, and the alterable battery charger does not have a built-in AC/DC adapter.

Abstract: Disclosed is an audio/video signal auto switching system. The system contains a last-on function block, a memory function block, a switch-back function block, and a memory-reset function block. If there is a plurality of input signals received by the system, then the last-on function block will select a last input signal as an output signal, and the memory function block will record the input sequence of the plurality of input signals. If a non-output signal disappears, the memory-reset function block will sort the input sequence. If the last input signal disappears, the switch-back function block will select the output signal from the plurality of the signals based on the input sequence.