Alt-BEAM Archive
Message #04581
To: beam@sgiblab.sgi.com
From: Sean Rigter rigter@cafe.net
Date: Thu, 17 Jun 1999 07:04:30 -0700
Subject: [alt-beam] Re: 245 driver / reverser in 1 chip
Actually I haven't seen it before but won't work as described. It needs
a two (10K) resistors from each 74HC14 output in series with each 245
connection. The problem is the active output of the 245 must be isolated
from the 74HC14 output because the 245 is a buffer and the 14 output is
not "strong" enough to change logic levels. The resistors do the job.
However a 240 can do the same thing without the resistors and my own
AC157 or AC257 reverser (from many moons ago) does a nice job of
reversing motors too with a smaller package, less wiring and higher
output current.
wilf
"van Zoelen, Bram SSI-TSEA-352" wrote:
>
> Isn't this in the FAQ already?
> I think soo.
>
> Bram
>
> > ----------
> > From: Ben[SMTP:mesiti@pbq.com.au]
> > Reply To: beam@sgiblab.sgi.com
> > Sent: Tuesday, April 20, 1999 12:07 PM
> > To: mailing list
> > Subject: 245 driver / reverser in 1 chip
> >
> > <>
> > Here's a circuit I designed that uses the direction pin on a 245 to swap
> > the
> > polarity of the rear motor on a two motor walker. I'm pretty sure it will
> > work, but I haven't built it yet. Basically, for the rfront motor, the
> > driver is normal. One driver for each of the poles on the motor. But it
> > uses
> > another two, who's outputs have the microcore output on them as well, and
> > the inputs of these gates got to the motor, so when the chip reverses the
> > front motor remains in the sam direction. For the fron motor however, 2
> > outputs from the microcore go to the input of one gate, and the output of
> > another gate. The outputs and inputs of these gates respectively go to the
> > motor, however unlike with the front motor, the rear motor's second set of
> > drivers is reversed (the ones coming from the "inputs" of the second set
> > of
> > drivers); so when the chip's direction pin is enable (from a reverser
> > sensor
> > etc), the drivers reverse direction and the rear motor's polarity changes,
> > Making the walker go backwards.
> >
> >
> > Any comments? What do you guys (and girls) think??
> >
> >
> >
> >
> > __________________________________________________________________________
> > __
> > I really need to come up with a good saying.....
> > ICQ#24602841
> > http://www.geocities.com/TimesSquare/Cavern/9282/
> >
> >
> >
--
Hey, come visit my homepage at
http://www.geocities.com/Area51/Nebula/1710/
Southpark, Mechwarrior2, V&V, Al-Qadim, and Milla Jovovich!
------------------------------------------------------------------------
eGroups.com home: http://www.egroups.com/group/alt-beam
http://www.egroups.com
- Simplifying group communications
Home