上海铁路局电务修制所试制成功的“书写电传机”是利用开环自动控制的原理,将发讯笔的动作分成X、Y两个方向,带动两个光栅圆盘,通过光敏电阻,接收脉冲信号,驱动两台步进电机,带动收讯笔作发讯笔同样的动作。它具有结构简单,操作方便,无需译码编码,一台发讯机可带动十多台收讯机 The successful trial-writing “telex machine” of Shanghai Railway Administration repairs the system by using the principle of open-loop automatic control and divides the action of the sending pen into X and Y directions and drives two grating discs through the photosensitive resistor , Receives the pulse signal, drives two stepping motors, drives the receiving pen to make the same action as the sending pen. It has a simple structure, easy operation, without decoding coding, a transmitter can drive more than a dozen receiving machine