Patent ID: 7710123

Claim:
A voltage variance tester comprising: a first testing circuit comprising a first adjustable power source and a first electrical switch; a second testing circuit comprising a second adjustable power source and a second electrical switch; a third testing circuit comprising a third adjustable power source and a third electrical switch; a first signal generator connected to the third adjustable power source and providing a first signal; a second signal generator connected to the second testing circuit and the first signal generator to receive the second adjustable power source and the first signal and providing a second signal according to the second adjustable power source and the first signal; a third signal generator connected to the third testing circuit and providing a third signal; a connector arranged to connect to a power connector of a motherboard, the connector having a first to a third terminals connected to the first to third testing circuits respectively for receiving the adjustable power sources via the electrical switches, a fourth to a sixth terminals connected to the first to the third signal generators respectively for receiving the first to the third signals, and a seventh terminal; and a control circuit connected to the seventh terminal of the connector for receiving a power on signal to turn on the first to third electrical switches, wherein, voltage variances of the motherboard are tested by adjusting the first to the third adjustable power sources.