Newsgroups: comp.robotics
Path: brunix!uunet!haven.umd.edu!darwin.sura.net!zaphod.mps.ohio-state.edu!swrinde!news.dell.com!fenian!timd
From: timd@fenian.dell.com (Tim Deagan)
Subject: Re: ==]  MOSFET help for steppers...
Message-ID: <1993Apr21.155400.1574@raid.dell.com>
Sender: news@raid.dell.com (Net News Admin)
Nntp-Posting-Host: fenian.dell.com
Reply-To: timd@fenian.dell.com
Organization: SLAMDANZ CYBRNETX
References: <sDqc3B2w165w@sys6626.bison.mb.ca>
Date: Wed, 21 Apr 1993 15:54:00 GMT
Lines: 37

In article sDqc3B2w165w@sys6626.bison.mb.ca, 
baden@sys6626.bison.mb.ca (baden de bari) writes:
> Problem
> 1:  I've got some 4 wire steppers.  I put the darkest line to + and the
> other 3 to the 3479P... worked, kinda. 

The 6-wire stepper were probably 4-phase steppers.  The 4-wire steppers
are probably 2-phase steppers or Variable Reluctance (VR) (3-phase) steppers.  

2-phase steppers are driven as two seperate coils.   
2-phase excitation compared to 4-phase
excitation doubles the resistance, halving input power and current.
Sequence the 2-phase stepper by exciting coil 1 then coil 2 then reverse
the polarity on coil 1 then reverse the polarity on coil 2.

VR steppers get excited in linear sequence.  (either by
exciting one coil at a time or all but one at a time)

Bottom line is to stick with the 4-phase (6 or 5 wire) steppers to
make the same circuit work all the time. 

 I built a VERY simple 2-bit 4-phase stepper circuit (using 4-phase 
wave excitation) by using a 74LS191 up/down counter the bottom 
two bits of which feed into a 7445 BCD (open-collector) decoder.
The bottom four bits of the decoder drive a 4001 (for inversion of
the four bits) which drives four IRF511 MOSFETs.  the IRF511s drive the 
4 phase wires of the stepper.  The D/U# line on the '191 is the
direction bit and the CP line is the step bit.  It doesn't do the
fancy stepping sequences, but it works _really_ well.  (it will
also drive the 3-phase steppers in a pinch)

---
{{{{{{{{{{{{{{{{{{{{{ timd@fenian.dell.com }}}}}}}}}}}}}}}}}}}}}}}}}}}}
             Rev. Tim Deagan - Official Obnoxious Poster
No one but me is responsible for anything I write, believe in or preach
* "It is difficult to free fools from chains they revere." - Voltaire *

