Hardware Reference
In-Depth Information
This particular stepper motor has these markings on it:
12 V
0.16
A/Ø
75 W
100
S/R
Date 42-83
This motor was clearly marked as a 12 V device. The 0.16 A/Ø marking tells us that
each winding (phase Ø) is rated for 160 mA. The following calculation confirms that the
winding resistance is 75 W, which is consistent with the printed current rating:
V
R
I
=
12
75
160
=
=
mA
The 100 S/R marking tells us that this motor has 100 steps per revolution. It's really
nice when you get all the information you need up front.
Your Junk-Box Motor?
Old 5.25-inch floppy-disk drives are getting scarcer these days. So what about other
stepper motors that you might have in your junk box? How can you determine whether
you can use one?
The first thing you must check is the type of motor. This chapter focuses on unipolar
motors that have three or more step windings with a common connection. The floppy-disk
stepper motor that I'm using in this chapter is shown in Figure
6-2
. Notice that this motor
has four separate windings, labeled
L
1
through
L
4
. These have a common connection to
a black wire coming out of the motor. To make this motor step, each winding must be
activated in sequence.
Figure 6-2.
Floppy-disk stepper motor windings
