Abstract: An exemplary tuner circuit is provided. The circuit includes a power control system, a first switch module, and a second switch module. The first switch module is connected between the power control system and an electronic component. The second switch module is connected between the power control system and a tuner. The power control system is independent of the electronic component it supplies. When the tuner is turned on, the power control system outputs a high level voltage to the first switch module and outputs a low level voltage to the second switch module, the first switch module disconnects power to the electronic component, the second switch module re-establishes a connection between the power control system and the tuner according to the low level voltage output by the power control system.

Abstract: An exemplary key detection circuit is provided. The key detection circuit includes a number of key pins, a number of switches, and a number of general purpose input/output (GPIO) interfaces. The switches include a first group of switches and a second group of switches. Each one of the first group of switches is connected to one of the key pins, and each one of the second group of switches is connected to two key pins. Each GPIO interface corresponds to one key pin, one GPIO interface is set to receive input voltages which alternate between a high level and a low level, the other GPIO interfaces are set to receive a fixed level voltage input.

Abstract: A printed circuit board is provided. The printed circuit board includes a number of welding points in a row for soldering of a series of welding feet of a component thereto. Each welding point includes a welding hole defined in the printed circuit board and a C-shaped welding pad surrounding the welding hole. The welding pads have an opening facing an adjacent welding pad.

Abstract: A signal processing circuit includes an infrared signal processing circuit, a button signal processing circuit, and an MCU. The infrared signal processing circuit includes an infrared receiver. The button signal processing circuit includes a first button and at least one second button. The MCU includes a power input port, an infrared signal detecting port, and at least one button signal detecting port. A first terminal of the infrared receiver and a first terminal of the first button are connected to the infrared signal detecting port. A first terminal of the at least one second button is connected to the power input port via a first resistor, and further connected to the at least one button signal detecting port, a second terminal of the first button and a second terminal of the at least one second button are grounded. Thus a more effective infrared detector is available.

Abstract: An exemplary anti-pop circuit for use in an electronic device includes a switch module, a first path module, and a second control module. The first path module outputs a first response signal when the electronic device is being started, the switch module cuts off the connection between the audio IC and the speaker in response to the first response signal. The second control module includes a charge/discharge unit and a second path module. The charge/discharge unit is charged by the DC power supply when the electronic device is being started, and discharges to the second path module when the electronic device is being shut down. The second path module outputs a second response signal when the electronic device is being shut down, the switch module cuts off a connection between the audio IC and the speaker in response to the second response signal.

Abstract: An electronic device powered by a voltage of a power supply includes a load, a switching module connected between the power supply and the load, and an overvoltage protection circuit. The overvoltage protection circuit comprises a control unit presetting a first predetermined voltage and an overvoltage protection unit. When the voltage is larger than the first predetermined voltage, the control unit generates a protection signal to control the overvoltage protection unit to generate a first control signal, the switching module cuts off an electrical connection between the power supply and the load in response to the first control signal.

Abstract: A power switch circuit includes a pulse width modulation (PWM) control circuit having a first frequency control terminal and a second frequency control terminal for outputting predetermined frequency signals, a first switch circuit, a second switch circuit, a first resistor connected between the first frequency control terminal and the first switch circuit, a second resistor connected between the first frequency control terminal and the second switch circuit, a first filtering circuit having a third resistor and a first capacitor, and a second filtering circuit having a fourth resistor and a second capacitor. A first terminal of the first capacitor is connected to the first switch circuit and a second terminal of the first capacitor is grounded via the third resistor. A first terminal of the second capacitor is connected to the second switch circuit and a second terminal of the second capacitor is grounded via the fourth resistor.

Abstract: A mute drive circuit includes a micro-controller including an I/O port; a mute circuit; and an npn transistor. When an electronic device using the mute circuit is plugged into an AC power source, the I/O port is set to the logic low, the mute circuit performs the mute mode. When the electronic device is turned on, the I/O port is controlled set to the logic low for a period and then be pulled up to the logic high, the mute circuit performs the mute mode for the period and then enters into the normal mode. When the electronic device is turned off, the I/O port is controlled to set to the logic low, the mute circuit performs the mute mode. When the electronic device is unplugged from the AC power source, the I/O port is pulled down to the logic low, the mute circuit performs the mute mode.

Abstract: A photoelectric switch control circuit includes a first resistance; a first capacitance; and a photoelectric switch having a plurality of contacts which comprise a first to a fourth contacts. The first contact is grounded, one end of the first resistance, the second and the third contacts of the photoelectric switch and one end of the first capacitance connects at node A, the fourth contact is connected with the processing unit and grounded via a second resistance, the other end of the first resistance is connected with a voltage source, the other end of the first capacitance is grounded.

Abstract: A power supply circuit for providing over-voltage protection includes a power supply unit and an output. The power supply unit includes a power input control terminal and a power output terminal. The power output terminal configured for connection to the output for supplying power to a load connected to the output. The power supply circuit includes an over-voltage response unit for connection to the output, and a control unit. The control unit is connected between the over-voltage response unit and the power input control terminal. The over-voltage response unit is configured for turning on the control unit. The control unit is configured for transmitting a control signal to the power supply unit to control the power supply unit to stop outputting power when it is turned on.