Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!mit-eddie!uw-beaver!zephyr.ens.tek.com!gvgpsa!gold.gvg.tek.com!grege
From: grege@gold.gvg.tek.com (Greg Ebert)
Newsgroups: sci.electronics
Subject: Re: Help needed with stepper motor.
Keywords: Stepper motor
Message-ID: <2309@gold.gvg.tek.com>
Date: 10 May 91 17:34:28 GMT
References: <12076@jarthur.Claremont.EDU>
Organization: Grass Valley Group, Grass Valley, CA
Lines: 51

In article <12076@jarthur.Claremont.EDU> ypham@jarthur.claremont.edu (Yen) writes:
>Hello netters,
>
>I am doing a project that need a stepper motor.  I was able to found 
>
> [...]

There are 2 types of steppers I know of: 4-wire and 6-wire. In the 
following discussion, the word 'high' means a DC source. It can be
positive or negative. About 12-15 volts usually works. Each state is
about 3-10 milliseconds for a "typical" stepper. To be safe, start out
with small voltages and time intervals, then work your way up if you
need more torque or if it's too fast.

*****REMEMBER*****  You have inductive loads! Makes sure you provide a
return path with a reverse-biased diode. If you aren't nice to inductors,
they will get revenge !

4 wire: There are 2 separate windings. Use an ohmmeter to identify them.

Call the wires on the first pair A and B; The second pair C & D
To make the motor rotate, do the following sequence:

	A=high  B=gnd  C=open D=gnd
	A=open  B=gnd  C=high D=gnd
	A=gnd   B=high C=gnd  D=open
	A=gnd   B=open C=gnd  D=high
	   (repeat)

If the motor just vibrates, interchange A & B. To reverse, do the sequence
backwards.

- - 

6 wire: There are 2 separate center-tapped windings. Use an ohmmeter to
identify them; the lowest resistance means you found the center tap.

Tie both center taps to high. Call the remaining 2 wires on one winding A & B.
Call the last 2 C & D. The sequence is:

	A=gnd  B=open C=open D=open
	A=open B=open C=gnd  D=open
	A=open B=gnd  C=open D=open
	A=open B=open C=open D=gnd
	   (repeat)

If the motor just vibrates, interchange A & B. To reverse, do the sequence
backwards.

- - -
You can do half-steps by logically ORing adjacent states.