Newsgroups: comp.robotics
Path: brunix!sgiblab!nbn!well!pacbell.com!decwrl!hookup!swrinde!cs.utexas.edu!howland.reston.ans.net!math.ohio-state.edu!magnus.acs.ohio-state.edu!csn!col.hp.com!news.dtc.hp.com!hpscit.sc.hp.com!cupnews0.cup.hp.com!tak
From: tak@cup.hp.com (Tom Knorr)
Subject: Re: Driving Stepper Motors
Sender: news@cupnews0.cup.hp.com (News Admin)
Message-ID: <CMru5u.JzC@cup.hp.com>
Date: Wed, 16 Mar 1994 19:01:05 GMT
References: <94031506310019@comedy.com>
Nntp-Posting-Host: hpindqq.cup.hp.com
Organization: Hewlett Packard CCSY
X-Newsreader: TIN [version 1.2 PL1.3]
Lines: 42

Robert Bierer (robert.bierer@comedy.com) wrote:
: Tim,

: I've just received a book on robotics that includes a chapter for
: driving stepper motors (dc motors and speed control of.  In chapter 14
: of "ROBOT BUILDER'S BONANZA, 99 inexpensive robotics projects" by
: Gordon Mccomb (c)1987 (ISBN:0-8306-0800-1).  It cost me $25Cdn and has
: an abundance of information and tips on building robots.

: Chapter 14 shows several circuits to drive stepper motors and goes into
: explaining how they work.  I've got as much knowledge (or less) as you
: do about this stuff and this book explained quit a few things.

Since this book has come up in several postings:

There are some serious problems in some of the circuits printed in this 
book (use common sense and check your pin-out against some commercial 
references).

I really liked the ideas demonstrated in the book and found most of 
the general explanations (e.g. how to control stepper motors) useful.

The TTL circuit in the stepper motor chapter (6 wire motor) has the 
GND and VCC of the 7476 just reversed in the diagram (kindofa uncommon chip).
Makes for a hot bug !! Also I found grounding the reset and preset pins 
isn't too good for proper operation (I left them open). 
Other than that it works pretty nice. 

I used a 6-wire stepper of a gutted floppy drive. The two same colored 
(red) wires are +12V and the other to control the coils. If your motor 
only steps back and forth instead of forward (or backward) check your 
wiring, your TTL outputs are 1,2,3,4 and the coil wiring is 1,3,2,4 (I 
believe). 

P.s.: I'm working for HP in an unrelated field and opinion's expressed
in this posting are mine, not HP's. 

Happy stepping

tak


