Speed control device for a ceiling fan

摘要

The present invention provides a speed control device for a ceiling fan which comprises a MOSFET, a signal generator and an overload protector. The MOSFET is connected to the ceiling fan and power source via a bridge rectifier for controlling power supplied to said ceiling fan. The signal generator provides a control signal to the MOSFET, wherein the control signal is a cyclic signal whose voltage level is progressively increased and then decreased when it reaches a predetermined level whereby the MOSFET is cyclically and progressively turned on and turned off. The overload protector is connected between the drain and gate of said MOSFET for detecting an abnormally large current flow through said MOSFET to cut off said MOSFET thereby preventing the ceiling fan from possible damage.