芯片PCF8951共有四个A/D输入通道：AD0，AD1，AD2，AD3,分别与四个电位器(R1,R2,R3,R4)连接，用以调节电位器的输出电压。其中AD0通道既可测量电位器输出电压，也可用于测量从J1插座输入的外接电压，须用开关J2加以选择。J4插座提供由PCF8591输出的时钟方波信号。SAA1064驱动四个数码管显示一路AD转换后得到的数据。-PCF8951 chip, there are four A/D input channels: AD0, AD1, AD2, AD3, respectively, with four potentiometers (R1, R2, R3, R4) connected to regulate the output voltage potential. AD0 channel which can be measured potentiometer output voltage can also be used to measure the input from the J1 socket external voltage, to be used to select switch J2. J4 socket output from the PCF8591 clock square wave signal. SAA1064 drivers of four digital display along after AD conversion data.