Abstract: A fan capable of resisting reversed flow includes a frame body, a fan wheel and at least two baffle parts. The frame body has an inlet and an outlet and provides at least an actuating device at the outlet side. The fan wheel is rotationally attached to the inner side of the frame body and provides a hub and a plurality of fan blades extending outward radially along the periphery of the hub. One of the baffle parts is pivotally connected to the outlet side of the frame body and the first baffle part connecting with the actuating device. When the fan stops running, the other baffle part, which is without connecting with the actuating device, pushes the slide element of the actuating device to slide for the baffle part closing the outlet.

Abstract: A protective circuit for a motor includes a motor, a drive unit and a control unit. The drive unit is connected to the motor to drive the motor. The control unit is connected to the drive unit to control output or drive current of the drive unit. The motor and the drive unit are incapable of generating high temperature due to excessive drive current being limited by the control unit such that damage of the drive unit and the motor can be avoided. The control unit is a comparator or an operation amplifier connecting with a comparison circuit composed of a capacitor and a plurality of resistors to produce control signal.

Abstract: A protective circuit for a motor comprises a rotational unit; a drive unit and a control unit. The drive unit is connected to the rotational unit to drive the rotational unit in running. The control unit is connected to the drive unit to control output or drive current of the drive unit. The rotational unit and the drive unit do not occur high temperature due to excessive drive current such that damage can be avoided. The control unit is a comparator or an operation amplifier connecting with at least a comparison circuit composed of a capacitor and a plurality of resistors to generate control signal.

Abstract: A complex type temperature control circuit for a cooling fan includes two or more resistance series sets. The first resistance series set is a resistor connecting in series with a temperature sensing member. The second resistance series set is a resistor connecting in series with a temperature sensing member too. Further, the second resistance series set is connected in parallel to the temperature sensing member of the first resistance series set. Hence, the complex type temperature control circuit can make a voltage change rate resulting from temperature change increases such that a range of fan rotational speed change can be increased under the same temperature change.