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:

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 rec> Hello all, I have a question.

If you want to avoid the parallel port for controlling stepper motors, then you can look at the G100 from Gecko

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