用变压器+整流桥+滤波器+稳压器构成5v的直流电源，以此作为D/A转换器（DAC0832）的基准电压，用AT89C51+8155+键盘+LED的单片机小系统控制进入DAC0832的数字量达到数控的目的 -transformer rectifier bridge filter Regulators constitute 5v DC power supply, as D / A converters (DAC0832) voltage, AT89C51 8155 with the keyboard LED small SCM system control access to the figures amounted DAC0832 The purpose of NC