Re: Robot Info

[Erick Wagner <wagnere@netcom.com>]

fl332@cleveland.Freenet.Edu (John L. Graham) wrote:

> I'd start with a catalog from Vernier Software, you can
> reach them at 1-503-297-5317, or email them at Vernier@Vernier.com.
> They carry lot's o'stuff for technical fun with your Apple II including
> stepper motor drivers. They also sell a couple of neat and really sound
> project books and one of the projects is building a stepper driver,
> which would be the foundation of your robot project...

I'll second what John said and also mention that the "better" stepper
motor project is in their second project book ("Chaos in the
Laboratory").  In my opinion, it is better because it uses only one
component (an IC chip from Allegro/Sprague) to control all aspects
with controlling the stepper.  This greatly simplifies the circuit
and makes it relatively easy to program.  The project from the first
book ("Build a Better Mousetrap") uses many more components and you
have to concern yourself with activating each coil in the motor in
the proper sequence.  The Allegro chip (a UCN5804, I believe) makes
the control of Unipolar (not Bipolar) steppers easy to control.  The
Unipolar motor that Vernier includes in their $16 kit has a gearbox
attached to.  If you don't like this motor you can always buy another
from a local or mailorder surplus electronics store.

The Vernier kits come only with the circuit board and components;
instructions are NOT included.  The descriptions, instructions, and
diskettes with sample programs are in the two lab books.  Each book
has about a dozen projects.  Approx price $25 each.

If the email address that John gave doesn't work.  Try
dvernier@vernier.com

To power the stepper motors (not the stepper motor controller chip)
you will need an external power supply.  Don't expect to use any
power sources from the Apple II for a couple of reasons: (1) the Apple
won't be able to supply enough current (especially if you have more
than one motor) and (2) electric motors tend to "dirty up" (by
introducing small spikes) the power source causing problems in
digital circuits.