Abstract: A soft start circuit for a forward/reverse rotation fan includes a forward/reverse switch unit, a soft start activation unit, a soft start control unit, a Hall IC and a driver IC, wherein the soft start activation unit comprises a first signal transmission loop and a second signal transmission loop. The soft start circuit activates the soft start control unit via a first instantaneous signal outputted by the first signal transmission loop or a second instantaneous signal outputted by the second signal transmission loop to make the soft start control unit output a control signal to a speed control terminal. When the rotating direction of fan is switched from one direction into another, the fan starts rotation in a soft start mode owing to high level of the control signal transmitted from the soft start control unit to the speed control terminal during initial rotation of the fan.

Abstract: An automatic power-off and actuation circuit for a fan comprises a drive unit, a detection unit, a voltage-modulating unit, a comparison unit, an auto-restart unit, a regulation unit and a controlled IC, wherein the detection unit is electrically connected to the drive unit, the voltage-modulating unit is electrically connected to the detection unit, the comparison unit is electrically connected to the voltage-modulating unit, the auto-restart unit is electrically connected to the comparison unit, the regulation unit is electrically connected to the auto-restart unit and the drive unit, and the controlled IC is electrically connected to the regulation unit and the drive unit.

Abstract: A fan failure detector for detecting whether a fan is locked with a drive IC, a coil and an inspection circuit, the drive IC outputting a pulse signal, the coil is electrically connected to the drive IC and driven by the drive IC, the inspection circuit is electrically connected to the drive IC and the coil, the inspection circuit includes an RC charge/discharge circuit, a diode, a second capacitor, a voltage divider and a transistor having an output terminal, wherein the RC charge/discharge circuit, the diode, the voltage divider and the transistor are sequentially connected in series, the second capacitor is electrically connected with the diode and the voltage divider, when the fan operates normally, the output terminal provides a low voltage signal, when the fan locks, the output terminal provides a high voltage signal to avoid a wrong judgment that the fan still operates normally.

Abstract: A fan failure detector means for detecting whether a fan is locked comprising a drive IC, a coil and an inspection circuit, the drive IC means for outputting a pulse signal, the coil is electrically connected to the drive IC and being driven by the drive IC, the inspection circuit is electrically connected to the drive IC and the coil, the inspection circuit comprises an RC charge/discharge circuit, a diode, a second capacitor, a voltage divider and a transistor having an output terminal, wherein the RC charge/discharge circuit, the diode, the voltage divider and the transistor are sequentially connected in series, the second capacitor is electrically connected with the diode and the voltage divider, when the fan operates normally, the output terminal provides a low voltage signal, when the fan locks, the output terminal provides a high voltage signal to avoid a wrong judgment that the fan still operates normally.

Abstract: An automatic power-off and actuation circuit for a fan comprises a drive unit, a detection unit, a voltage-modulating unit, a comparison unit, an auto-restart unit, a regulation unit and a controlled IC, wherein the detection unit is electrically connected to the drive unit, the voltage-modulating unit is electrically connected to the detection unit, the comparison unit is electrically connected to the voltage-modulating unit, the auto-restart unit is electrically connected to the comparison unit, the regulation unit is electrically connected to the auto-restart unit and the drive unit, and the controlled IC is electrically connected to the regulation unit and the drive unit.

Abstract: A control circuit for fan operating comprises a drive operating circuit, a potential modulating circuit, a comparator and a switch circuit. The drive operating circuit at least has a voltage source, a drive IC, a Hall IC and a motor coil winding, the drive IC is connected with the voltage source, and the Hall IC and the motor coil winding are connected with the drive IC. The potential modulating circuit is connected with the drive IC of the drive operating circuit and has a modulating signal source to provide a PWM signal with a duty cycle. The comparator has an input end and an output end, the input end is connected with the potential modulating circuit, and potential state of the output end is determined in accordance with the duty cycle of the PWM signal. The switch circuit is connected with the drive IC of the drive operating circuit and the output end of the comparator, and operating state of the drive IC of the drive operating circuit is determined in accordance with potential state of the output end.

Abstract: A control circuit for fan operating comprises a drive operating circuit, a potential modulating circuit, a comparator and a switch circuit. The drive operating circuit at least has a voltage source, a drive IC, a Hall IC and a motor coil winding, the drive IC is connected with the voltage source, and the Hall IC and the motor coil winding are connected with the drive IC. The potential modulating circuit is connected with the drive IC of the drive operating circuit and has a modulating signal source to provide a PWM signal with a duty cycle. The comparator has an input end and an output end, the input end is connected with the potential modulating circuit, and potential state of the output end is determined in accordance with the duty cycle of the PWM signal. The switch circuit is connected with the drive IC of the drive operating circuit and the output end of the comparator, and operating state of the drive IC of the drive operating circuit is determined in accordance with potential state of the output end.

Abstract: A motor control circuit for forward/reverse rotation comprises a driving circuit, a switching circuit and a motor coil winding. The driving circuit has a driving source, a Hall IC and a driving IC. The driving source provides a signal to enable the Hall IC to output a control signal to the driving IC and the driving IC generates a driving signal after receiving the control signal. The switching circuit is applied for changing the transmitting direction of the control signal or the driving signal. The motor coil winding receives the driving signal and decides motor rotating direction according to the driving signal.

Abstract: A motor control circuit for forward/reverse rotation comprises a driving circuit, a switching circuit and a motor coil winding. The driving circuit has a driving source, a Hall IC and a driving IC. The driving source provides a signal to enable the Hall IC to output a control signal to the driving IC and the driving IC generates a driving signal after receiving the control signal. The switching circuit is applied for changing the transmitting direction of the control signal or the driving signal. The motor coil winding receives the driving signal and decides motor rotating direction according to the driving signal.