Patent ID: 8717008

Claim:
A fan speed testing system comprising: a voltage regulating module configured to receive an AC voltage signal and convert the AC voltage signal to a variable first DC voltage signal to adjust a rotational speed of a fan; a rotational frequency collecting module configured to detect the rotational speed of the fan and output rotational frequency signals; wherein the rotational frequency collecting module comprises a reflecting infrared sensor; the reflecting infrared sensor comprises a light emitting diode (LED) and a phototransistor; and a rotational frequency converting module configured to receive the rotational frequency signals and determine the rotational speed of the fan according to numbers and period of time level voltage switching in the rotational frequency signals; wherein two labels with an identifiable color are attached on a blade of the fan; and when the fan speed testing system is operational, light from the LED is configured to reflect off the two labels, and the light reflecting off the two labels is configured to turn on the phototransistor.