■ Implementation of arduino based speed control of stepper motor

●In ULN2003 IC Pin 1 to 7 is the input in which 1 to 4 pin is used as a input and pin 10 to pin16 is the output pin in which 13 to 16 pin used as a output connected to stepper motor. 

●When the input is the logic high by arduino uno then the transistor 1 will be activated.

●So the current from the winding flowing through the collector of the transistor 1 and going out from the emitter and flowing to the base of the transistor 2 and goes out to the emitter and back to the ground. 

The winding is energized and motor rotates in steps. 

●Video of arduino based speed control of stepper motor