Interesting Design Idea...Stepper Motor, PC, etc..

you could do that pretty easily with a microcontroller but that would
be overkill.  the motors you have are almost certainly split phase so
you just need four open collector drivers.

this is what you want:
74LS74 (dual d flipflop) wired as a two-bit recycling counter, that is,

D0=!Q0
D1=!Q1
CLK0=input clock
CLK1=!Q0
74LS08 (quad and gate) wired as so:
phase0 = !Q0 && !Q1
phase1 = Q0 && !Q1
phase2 = !Q0 && Q1
phase3 = Q0 && Q1

you can switch a '00 for the '08 if your drivers are inverting.  this
circuit will advance the stepper one step each time the input clock
rises.  of course, that only allows you to move it in one direction.  i
recently built something sort of like this (a small two stepper driver
for a cnc etch-a-sketch) that used two bits for each motor to select a
phase and thus was capable of bidirectional operation.

-chris

lmcgill wrote:

check out the UCN5804 Stepper Driver. Although out of production by
Allegro, these are fairly easy to come by. All rather depends upon the
stepper motor you want to drive though. the 5804 does not have terribly
high drive capability.

high performance and/or powerful steppers will need significantly more
effort. but the kind of thing you get from old printers and disk drives
is fine with a 5804. It really could not be much easier.

Peter Harrison

I've used this schematic before:
http://www.armory.com/~rstevew/Public/Motors/Steppers/stprcntl.gif

It works for unipolar stepper motors, and is really easy to build.

The 'S1' is what you pull high/low to change the direction of the
stepping (if i remember correctly.)  You could also buy a stepper motor
driver to do this for you.  Meanwhile the "12V" in the schematic should
really be around 5V, except in the case of the motor power terminal
(which depends on the motor you're using)


-Andrew W
reconnsworld

lmcgill wrote:

If you want to avoid the parallel port for controlling stepper
motors, then you can look at the G100 from Gecko
(http://www.geckodrive.com/ ).

This is a CNC controller that gets rid of the parallel port
problem.
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