Description Bipolar stepper motors always have only 4 wires.  They require a dual H-bridge to drive them.  Bipolar motors offer increased torque compared to unipolar motors.  Flyback diodes are required to prevent voltage spikes when the power to the coil is turned off and the stepper motor acts like a generator briefly (back-emf). Note: You … Continue reading Arduino + Stepper (A3967) EasyStepper