| 20120007534 | ROTATION SPEED CONTROL DEVICE FOR A HEAT-DISSIPATING FAN - A rotation speed control device for a heat-dissipating fan includes an impedance unit, a regulating unit, and a driving circuit. The impedance unit includes a first resistor having a first end connected to a first node, and a second end connected to a second node, and a second resistor having a third end connected to the second node, and a fourth end. The regulating unit is connected to the impedance unit and is configurable for varying an effective impedance of the impedance unit to adjust magnitude of current flowing through the impedance unit. The driving circuit is connected to the impedance unit and is adapted to control rotation speed of the heat-dissipating fan according to the magnitude of the current flowing through the impedance unit. | 01-12-2012 |
