The work principle of traditional signal machines and new type LED signal machines are presented in this paper.The test principium and its test circuits of new type LED signal machines are described.

• 本文介绍了传统的信号机和新型LED信号机的工作原理,并介绍了对新型LED信号机的检测原理及检测电路,同时简要介绍了检测报警系统的构成。