The displacement device has two kind of power supply , dc and ac , which can insure the stability and adaptability in field application . mc1404b counter chip responding for accurate signal replacement was set in the internal circuit . the display component adopts the 7135 led display circuit with common cathode 测量仪采用交直流两种形式供电,这样既方便现场的使用又可以保证电源供电的稳定性,其内部电路中采用mc1404b计数器芯片,能够准确的进行复位调零功能,显示部分采用7135共阴极led的显示电路,这种芯片精度高、分辨率高、能准确检出极性。