A kind of rotating speed sensor is designed by using light-sensitive Z-element to measure the real-time rotating speed of rotary device.The characteristics of Z-element are tested.Its V-I characteristic curve can be depicted by an"L"figure.As the light intensity becomes stronger

the limit point moves toward upper left.The special nature of Z-element is analyzed in the semiconductor theory.This photoelectric rotating speed sensor

whose resolving power is 0.4 rad/s

is made by light-sensitive Z-element as photoelectric conversion element

the infrared light and signal adjustive circuit

and this sensor can realize the function of transferring the quantity of rotating speed into the digital impulse signal.Because of the special properties of the Z-element

the sensor has the features of simple circuit

high response speed and long spectrum range.