由四个双稳触发器加上反馈电路组成二——十进计数器已被人们所熟悉,改变反馈的方式可以得到多种结构形式的十进计数器,如8421,2421,6421等。目前在电子工业、自动化控制技术中广泛采用8421代码的二——十进制计数器,其方框原理图如图1。设双稳触发器采用pnp晶体管正脉冲触发,初始状态在复 By the four bistable flip-flop with feedback circuit composed of two - decimal counter has been known, changing the feedback can be a variety of forms of decimal counter, such as 8421, 2421, 6421 and so on. Currently in the electronics industry, automation and control technology widely used 8421 code two - decimal counter, the block diagram shown in Figure 1. Set the bistable trigger pnp transistor positive pulse trigger, the initial state in the complex