Unipolar Stepper Motor
Unipolar Stepper v/s Bipolar Stepper
Unipolar Stepper Motors utilise tapped coils, of which each side can be independently magnetized. Because the current running through each coil will be running in a different direction dependent on which side of the coil is magnetised, the polarity of each phase can be reversed without reversing the current of the entire circuit.
Both uni-polar and Bipolar steppers are used widely in projects. However, they have their own advantages and disadvantages from the application point of view. The advantage of a uni-polar motor is that we do not have to use a complex H bridge circuitry to control the stepper motor. Only a simple driver like ULN2003A will do the task satisfactorily. But, there is one disadvantage of uni-polar motors. The torque generated by them is quite less. This is because the current is flowing only through the half the winding. Hence they are used in low torque applications.
a uni polar stepper motor has 6 wires , two center tap , and 4 signal wires . so that it can be controlled directly from a i/o port ... or with spst relays as a bipolar stepper motor /// practicaly speaking... a unipolar stepper motor is both a bipolar and a unipolar stepper motor at the same time... where-as a bipolar must have reversals in polarity , and can only operarate as bipolar.
Thomas E. Pierre
I use this motor to roll up a large tapestry on my wall so that it can be used as a projection screen. It's a solid little motor with plenty of torque for the job. Docking one star because it emits a high-pitched whining sound, especially at low speed. This is common for stepper motors, but it's louder than I expected and kind of annoying for a living-room application; other than that I have no complaints. I control it with a Raspberry Pi 3 and the following power source and motor driver. Works a treat. LE® Power Adapter, Transformers, Power Supply For LED Strip, 12V, 3A Max, 36 Watt Max Robotlinking A4988 Stepstick Stepper Motor Driver Module + Heat Sink for 3d Printer Reprap (Pack of 5 Pcs)
J D