# Stepper Motors

#### nanobyte

Joined May 26, 2004
120
While doing some reading on stepper motors I encountered a sentence saying that most stepper motors have four stator windings that are paired with a center-tapped common. What is a center-tapped common?

#### Jalal

Joined Jan 30, 2006
1
Originally posted by nanobyte@Jan 30 2006, 02:07 PM
While doing some reading on stepper motors I encountered a sentence saying that most stepper motors have four stator windings that are paired with a center-tapped common. What is a center-tapped common?
[post=13656]Quoted post[/post]​
Dear,
Each coil has two terminal.Say the four coils are aa' , bb' , cc' and dd'.Center tapped common means a'b'c'd' are shorted making a common point.You can call it as a neutral point of a f 4 wire star connected system. You give supply in a, b, c, d in a sequential way and the motor runs.

#### peajay

Joined Dec 10, 2005
67
> four stator windings that are paired with a center-tapped common.

This is just like the two coil motors, except that each coil is center-tapped, so there are six wires coming out of the motor instead of four. That way you connect each center tap to the supply voltage for the motor, then ground each of the remaining four wires in sequence to turn the motor, which is much simpler than having to reverse polarity on the coils like you have to do with the non-center-tapped variety.

You can also drive these motors just like the non-center-tapped variety by simply ignoring the center tap.

#### thingmaker3

Joined May 16, 2005
5,084