Abstract: A circuit for eliminating noise includes a sound card (30) with an audio signal output, a power supply (10) for providing working voltage to the sound card, a first transistor (Q1), a second transistor (Q2), and a third transistor (Q3). The power supply has a power good pin, a PSON# pin, and a standby voltage pin. During powering on time of the sound card, the power good pin is at low level and the second transistor is therefore turned on to ground the audio signal output so as to eliminate turn-on noise. During powering down time of the sound card, the PSON# pin turns from low to high level to turn on the third transistor before the audio power for providing working voltage to the sound card is powered down, thus the first transistor turns off, and the second transistor turns on to ground the audio signal output of the sound card so as to eliminate turn-off noise.

Abstract: A CMOS clearing circuit mounted on a motherboard of a computer includes a south bridge chip and a switch member respectively mounted on the motherboard. The south bridge chip includes a reset terminal and an input terminal. The switch member is configured for controlling one of the reset terminal and the input terminal of the south bridge chip. If the switch member controls the reset terminal, the input terminal is disconnected from the switch member and the switch member is capable of controlling the reset terminal of the south bridge chip to be selectively connected to ground or a voltage source provided by the motherboard. If the switch member controls the input terminal, the reset terminal stays connected to the voltage source and the switch member is capable of controlling the input terminal of the south bridge chip to be selectively connected to ground or the voltage source.

Abstract: A motherboard includes a printed circuit board (10), and at least a power/ground trace (20) formed on the printed circuit board. The trace includes a pair of main lines (14, 24) and at least a protection line (12, 22) connected between the main lines. A width of the main lines is constant and wider than of the protection line. Wherein when a current flowing through the power/ground trace exceeds a maximum current the protection line can endure, the protection line is burnt and disconnected from the main lines, thereby generating less smoke and protecting components connected with the trace of the motherboard from damage due to excess current.

Abstract: A CMOS clearing circuit mounted on a motherboard of a computer includes a south bridge chip and a switch member respectively mounted on the motherboard. The south bridge chip includes a reset terminal and an input terminal. The switch member is configured for controlling one of the reset terminal and the input terminal of the south bridge chip. If the switch member controls the reset terminal, the input terminal is disconnected from the switch member and the switch member is capable of controlling the reset terminal of the south bridge chip to be selectively connected to ground or a voltage source provided by the motherboard. If the switch member controls the input terminal, the reset terminal stays connected to the voltage source and the switch member is capable of controlling the input terminal of the south bridge chip to be selectively connected to ground or the voltage source.

Abstract: A circuit for protecting a motherboard includes a power button (30), a first heat-generating component (10) of the motherboard with a first output terminal, a second heat-generating component (40) of the motherboard with a second output terminal, a first switch circuit (20) connected between the first heat-generating component and the power button; and a second switch circuit (50) connected between the second heat-generating component and the power button.

Abstract: A circuit for eliminating noise includes a sound card (30) with an audio signal output, a power supply (10) for providing working voltage to the sound card, a first transistor (Q1), a second transistor (Q2), and a third transistor (Q3). The power supply has a power good pin, a PSON# pin, and a standby voltage pin. During powering on time of the sound card, the power good pin is at low level and the second transistor is therefore turned on to ground the audio signal output so as to eliminate turn-on noise. During powering down time of the sound card, the PSON# pin turns from low to high level to turn on the third transistor before the audio power for providing working voltage to the sound card is powered down, thus the first transistor turns off, and the second transistor turns on to ground the audio signal output of the sound card so as to eliminate turn-off noise.

Abstract: A motherboard includes a printed circuit board (10), and at least a power/ground trace (20) formed on the printed circuit board. The trace includes a pair of main lines (14, 24) and at least a protection line (12, 22) connected between the main lines. A width of the main lines is constant and wider than of the protection line. Wherein when a current flowing through the power/ground trace exceeds a maximum current the protection line can endure, the protection line is burnt and disconnected from the main lines, thereby generating less smoke and protecting components connected with the trace of the motherboard from damage due to excess current.