The device is a signal tracking transducer. Its output quickly vary with input signal. It works on high-linearity analog optocoupler principle. It can convert AC/DC current/voltage input signal to electrically isolated, standard AC/DC current/voltage signal. Its input, outputs and power supply are electrically isolated from each other. The signal tracking transducer features high accuracy, high isolation, wide frequency band, fast response, low distortion, low drift and wide range of operation temperature. It can filter the common-mode noise generated during the transmission of signals from sensors, transducers or instruments and make a very good isolation and standardization of the signal. The transducer is particularly suitable for acquisition of high-speed transient waveform, harmonic analysis and fast testing and alarm systems. It can be applied widely to various measuring and controlling systems such as communication system, electrical power system, railway and various industrial control systems.