Lightings of many places need to be turned on and off automatically when someone passes.The device

using a couple of ultrasonic transmitter and receiver

can detect effectively anybody moving in a certain space

and control lightings on and off.When it works

the ultrasonic signals of a certain frequency are transmitted.Once someone passes

based on the Doppler effect

the frequency of the signals reflected by the moving body is different from the signals transmitted.According to the frequency difference the device can detect the motion exactly

and turn lightings on and off after a delayed time which can be set from 15 s to 30 min.The device can be installed easily in various places.Its front detecting distance can be set from 1.0 m to 5.5 m.