一、工作原理走纸电路(参看原电路图)由初始脉冲电路、开关键SW213、SW214、触发器、分频器、相位比较器及整形电路构成。其工作过程如下。由R205、C210和IC203构成的初始脉冲电路,在开机时由于电容C210两端电压不能跃变,IC203第1脚输入为零电平,反相输出为高电平,当电容C210的充电电压达到逻辑高电平时,经反相器在IC203第2脚得到一个低电平, First, the working principle Take the paper circuit (see the original circuit) from the initial pulse circuit, open the key SW213, SW214, flip-flop, divider, phase comparator and plastic circuit. The working process is as follows. The initial pulse circuit composed of R205, C210 and IC203 can not jump at the voltage at both ends of the capacitor C210 during power-on. The input of IC203 pin 1 is at zero level and the inverted output is at high level. When the charging voltage of capacitor C210 reaches Logic high, the IC203 by the inverter pin 2 get a low level,