**Abstract**

In this chapter, we report the design and fabrication of an improved speed synchronizer device in which two dc motors has been controlled on different sequences programmed by microcontroller. Depending on the programmed software, the device is used to command a rolling of machines, synchronizes the dc motors speed, and displays the result on liquid crystal display (LCD). Flash memory of the microcontroller is used to program for controlling this device where permanent memory is needed to store different parameters (codes for motor speed, LCD display, ratio control, and rotary encoder's feedback). The present simulation gives new reliable results with better performance for the speed and direction than the earlier available synchronizers. It has been shown that the speed and direction are dependent on both the ratio setting and frequency of encoder in two dc motors speed synchronizer. It is shown that this device is applicable for controlling, monitoring, and synchronizing identical processes and can be implemented in multiple domains, from textile industry and home control applications to industrial instruments.

**Keywords:** speed synchronizer, liquid crystal display, microcontroller, dc motors speed
