Alt-BEAM Archive
Message #04588
To: "'beam@sgiblab.sgi.com'" beam@sgiblab.sgi.com
From: Wilf Rigter Wilf.Rigter@powertech.bc.ca
Date: Thu, 17 Jun 1999 09:38:19 -0700
Subject: [alt-beam] Re: 245 driver / reverser in 1 chip
Oops, didn't see the schematic before I wrote this, so use 2K resistors
between the HC14 and each 74ALS245 I/O pin (the ALS245 is not my favorite
chip to begin with, oh well) BTW Judging from the type of schematic, you
modeled this circuit using some simulator design tool and it may work that
way because the effect of the output impedance of the HC14 was not included.
regards
Wilf Rigter mailto:wilf.rigter@powertech.bc.ca
tel: (604)590-7493
fax: (604)590-3411
> -----Original Message-----
> From: Sean Rigter [SMTP:rigter@cafe.net]
> Sent: Thursday, June 17, 1999 7:05 AM
> To: beam@sgiblab.sgi.com
> Subject: 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!
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