Abstract: A heat-dissipating fan includes a housing, an impeller, and a circuit board. The housing includes an air channel and a base. The base is mounted in one end of the air channel for supporting the circuit board. The impeller is rotatably mounted on the base and includes a hub and a plurality of blades. The circuit board includes at least one heat-generating electronic element mounted thereon. The heat-generating electronic element extends out of the hub in relation to a longitudinal direction of the housing, with at least one portion of the heat-generating electronic element located on a downstream side of the blades for dissipating heat generated by the heat-generating electronic element.

Abstract: A frequency-variable PWM motor drive circuit includes a drive IC member, a Hall IC member, a PWM converter circuit and a compensation unit. The drive IC member electrically connects with the Hall IC member, the drive IC member further includes a pin electrically connected with the compensation unit and the PWM converter circuit. The PWM converter circuit has a PWM input pin to receive a PWM signal, and converts it into a voltage signal. The compensation unit connects between the pin of the drive IC member and the PWM converter circuit. In operation, the compensation unit can improve a waveform of the voltage signal supplied from the PWM converter circuit, and then output it to the pin of the drive IC member. Consequently, the drive IC member can be steadily operated at predetermined motor speeds under various frequencies of the PWM signals.

Abstract: A heat-dissipating fan includes a housing, an impeller, and a circuit board. The housing includes an air channel and a base. The base is mounted in one end of the air channel for supporting the circuit board. The impeller is rotatably mounted on the base and includes a hub and a plurality of blades. The circuit board includes at least one heat-generating electronic element mounted thereon. The heat-generating electronic element extends out of the hub in relation to a longitudinal direction of the housing, with at least one portion of the heat-generating electronic element located on a downstream side of the blades for dissipating heat generated by the heat-generating electronic element.

Abstract: A frequency-variable PWM motor drive circuit includes a drive IC member, a Hall IC member, a PWM converter circuit and a compensation unit. The drive IC member electrically connects with the Hall IC member, the drive IC member further includes a pin electrically connected with the compensation unit and the PWM converter circuit. The PWM converter circuit has a PWM input pin to receive a PWM signal, and converts it into a voltage signal. The compensation unit connects between the pin of the drive IC member and the PWM converter circuit. In operation, the compensation unit can improve a waveform of the voltage signal supplied from the PWM converter circuit, and then output it to the pin of the drive IC member. Consequently, the drive IC member can be steadily operated at predetermined motor speeds under various frequencies of the PWM signals.