Talk:Motor FAQ

The section:

Stepper motors vs Servo Motors vs DC Gear Motors

"Servo Motors (Hobby) Servo Motors are DC motors coupled with internal gearing and some control electronics that allow you to move the motor to a precise position. Servos function using information produced by a computer or a microcontroller called Pulse-width-modulation. By sending a certain repeating signal to the Servo, it will move to that certain point. In terms of a reprap, a servo would need to either be modified or purchased as a "full rotation servo". In a reprap, servos require closed loop feedback system and usually involve an optical or magnetic rotary encoder. They generally will offer higher torque than comparable steppers. Servo motors use three wires, Ground, Power, and PWM. " Has been revised to be more specific, however I don't believe this has made it more accurate. Hobby servo's are a type of servo, but despite their popularity, in the context of industrial robotics are by no means the only game in town. If hobby servo's need to be mentioned specifically, it should be in addition to their more application-suitable brother: the continuous rotation DC servo motor. Not in it's place. --JohnnyCooper

In the section:

Stepper drivers vs Stepper Controllers

It is claimed: "a very small stepper may be driven directly from the controller", wouldn't that apply solely to unidirectional stepper motors?, since a bi-directional requires a phase change.

... with a "H-bridge"-setup and 4 transistors per coil (or 8 for a bipolar motor) you can switch the coils accordingly between Vdd and GND in either direction.

But unipolar requires only one transistor per coil, so is much easier to build and control ...

--VDX