Switching power supply ( visual adjustable ), based on 51 single-chip C procedures, for the simulation interface circuit, can be easily seen from the program. This procedure through the keyboard matrix scanning, after AT89S52 or compatible MCU processing, the output to 4 the total of eight vaginal digital tube display, as well as the output to the DAC0832 conversion, and then by the amplifying circuit can output 0 - 24 voltage-Switching power supply ( visual adjustable ), based on 51 single-chip C procedures, for the simulation interface circuit, can be easily seen from the program. This procedure through the keyboard matrix scanning, after AT89S52 or compatible MCU processing, the output to 4 the total of eight vaginal digital tube display, as well as the output to the DAC0832 conversion, and then by the amplifying circuit can output 0- 24 voltage.