[simpits-tech] phidgits + Building Gauges

[Rod Dale]

There's a small electronic device called a Photo Interrupter (PI) that could
be used. This consists of an IR LED (Infra Red) on one side and a
photo-transistor on the other. These are used in printers to indicate where
the carriage is. All you need to do is put a small piece of plastic on the
shaft of the stepper motor and each time this plastic piece passes between
the two parts of the PI it cuts the IR to the transistor and signals the
controller (PC, Basic Stamp, Phidgit etc) that the motor has turned one
revolution. If you could set up a counting program then you keep track of
the revolutions and hence the start point and any number of other points
too.
I got hold of a heap of old printers and stripped them of these devices and
the stepper motors - ready for this sort of thing.
Can anyone add to this theory ?
Rod
----- Original Message -----
From: Roy Coates <roy@flightlab.liv.ac.uk>
To: <simpits-tech@simpits.org>
Sent: Friday, October 25, 2002 5:34 AM
Subject: Re: [simpits-tech] phidgits + Building Guages


> On Thu, 24 Oct 2002 mysticz28@swbell.net wrote:
>
> > Gene Buckle wrote:
> > >
> > > The problem is that everyone and their brother has a neat method of
> > > driving a stepper motor, but nobody says anything about *feedback*
from
> > > that motor.
> >
> > That's because steppers can't talk back (or they would be servos).
> > Fortunately for them, you talk enough to take up their slack ;)
> >
>
> I was led to believe that you CAN get feedback from a stepper.
>
> Roy.
>
>
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