Design an Arduino Based Encoder Motor using PID Controller

This project uses an Arduino Nano to achieve precise motion and position control of an N20 Encoder Motor. The brain of the system is the Arduino IDE running a PID Controller Library, which calculates the exact error between the motor's target position or speed and its actual output, measured continuously by the motor's built-in encoder. Because the Arduino Nano's digital output pins cannot supply enough current or voltage to drive a motor directly, the circuit utilizes a custom transistor driver stage built using BD139 and BD140 complementary power transistors, supported by BC548 transistors and 100R and 4.7K resistors for biasing and signal control. The transistors act as electronic switches and amplifiers, translating low-power pulse-width modulation (PWM) control signals from the Arduino into higher power delivery to the N20 motor. By constantly monitoring the encoder feedback and adjusting the transistor switching states via the PID algorithm, the system automatically corrects for external loads or variations, holding the motor precisely at the desired speed or angle. All components are wired together conveniently on a breadboard using jumper wires, powered by an external power supply to ensure stable operation of both the logic and motor circuits.