Re: can you help identify a stepper motor?

Phil,

Stepper motors have 2 or more coils. Power is sequenced to the coils,
turning sometimes 1 on, sometimes 2 windings on. The armature will
"step" around, following the powered coils. There are typically 200
such steps for a full revolution. Stepper motors require electronics
(transistor switches) to turn the windings on and off in a prescribed
manner. These switches get "steps" from a computer to make the switches
sequence.

Servo motors are "precision" motors. Usually DC, and they work just
like a normal DC motor. Better parts, special cores/windings, bearings
etc. They will usually spin fine with a little power applied. Servo
motors need a different type of transistor switch to PWM (pulse width
modulate) the current to the motor winding. This switch controls the
percentage of time the current is on, and the direction it flows. The
PWM is controlled by a computer.

Don't connect the encoders until you determine what type they are. An
encoder is a slotted disk, with a photocell/LED pair that shines through
the slots. As the shaft of the motor turns, the slots interrupt the
light, and the photocell sees it. Actually, there are usually 2 or more
photocell/LED pairs, and either analog or digital or digital signals are
generated. These signals are normally 90 deg. out of phase, in
"quadrature". Electronic circuits can use these two signals to sense
direction and speed of the rotating part, and the signals can be thought
of as "steps", similar to the steps (pulse or square wave signals) we
send to the stepper motor drivers.

Hope this gives you some simple answers to your questions. There is an
abundance of information on steppers and servo on the net, also see this
list's FAQ (usually seen on the bottom of email'ed posts, see the text
added to your post below).

Alan KM6VV


Phil Jaster wrote:

>
> Alan,
>
> Thanks, Wow that was a fast response!!!!
>
> As I am brand new in this aspect of electronics, what is the
> difference in a stepper motor and DC servo motors????
>
> What is an encoder?
>
> Can I hook up DC power without damage to the encoders?
>
> Again Thanks,
>
> phil
>
> --- In CAD_CAM_EDM_DRO@egroups.com, Alan Marconett KM6VV <KM6VV@a...>
> wrote:
> > Phil,
> >
> > I think you have DC servo motors with encoders!
> >
> > Alan KM6VV
> >
> >
> > Phil Jaster wrote:
> > >
> > > Can anybody help identify the following?
> > >
> > > I have two stepper motors pulled from an unknown brand of a
> plotter
> > > printer, this printer was huge, capable of at least 30"
> > > paper . I have searched the internet and found the company of one
> of
> > > them but recieved NO reply from my email.....
> > >
> > > Both motors are 2.+ inches in diameter and vary in length but are
> both
> > > approx. 3 3/4 inches. [NEMA 23]?????
> > >
> > > They both are connected with 10 wire ribbon harness PLUS have what
> > > must be negative and positive DC connectors <both have a very
> obvious
> > > "+" sign by the factory red screw holding the wire connector lug
> onto
> > > the motor.>
> > >
> > > The motors mount on the shaft end of the motor which have pressed
> on
> > > fine toothed gears, of two different diameters.
> > >
> > > Both motors were made or sold in Chatsworth, CA 91311.
> > >
> > > One is marked Universal Magnetics, Inc. an "NMB company" It has
> the
> > > following identifing numbers: 10211-301-000 on the
> > > first line and ME2102617 in one space and 8523 following that.
> > >
> > > My other motor is labeled on the BODY with: Hathaway p/n 7925109
> REV
> > > B003, a customer p/n which is seven numbers or
> > > letters long but unreadable... then REV 4A and a small + sign near
> the
> > > RED painted wire connector lug on the motor.
> > >
> > > On its round cap covering the circuit board for the servo stuff it
> is
> > > labeled: Computer Optical Products, Inc and again the
> > > address of Chatsworth, CA 91311.
> > >
> > > Can anybody provide even approximent values for these motors????
> Can
> > > they be powered by the DC connectors without harming the stepper
> > > circuits??? How can I identify which wires in the ribbon are
> "used"
> > > for the servo information.
> > >
> > > I would like to be able to use these for x axis on my TAIG lathe
> or
> > > maybe for driving a home built plotter/engraver.
> > >
> > > would these be "good" for a first time project in stepper motor
> work
> > > or should i go with something less exotic like steppers from a dot
> > > matrix printer?????
> > >
> > > thanks in advance,
> > >
> > > phil jaster
> > >
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