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[DPRG] The quadrature blues

Subject: [DPRG] The quadrature blues
From: Sluggy slugmusk at linuxlegend.com
Date: Wed Aug 29 09:04:20 CDT 2001

"Jeffrey T. Birt" wrote:

> I should have mentioned that I'm using a reflective type sensors, therefore
> an even number of encoder divisions must be used.

I'm not sure I understand how reflective or transmissive should make a
difference as to the number of divisions you can sense. 

On the other hand, I am humbled that it didn't occur to me to mount the
sensors at an even 180 degree spacing and simply draw a wheel with an
odd number of divisions instead of jumping through all these hoops to
make an adjustable, and therefore unstable, sensor mounting.

In other news, I made a trip to Tanner's yesterday and purchased what
may be the last two Pittman GM8712 motors they had. These are indeed
wonderful little motors.

They also had some other Pittman motors, without gearheads, that looked
about the same size as the core of the GM8712. After I was already on
the road again, it occurred to me that we might be able to swap out the
armatures in the gearhead motors with the others to provide a longer
motor shaft more suitable for mounting an optical encoder. Obviously,
that involves pressing a pinion gear onto the new armature, but who
knows, it might be worth it.

I also got a couple of Buhler gear motors that they had in the display
case next to the PICs. They were $10 each. They have die cast cases,
have a small output shaft (I'm guessing 2.5 mm) with one flat and are
labeled 12V. With about 12.5 volts applied, the run at about 30 rpm (10
observed rotations in 20 seconds). The case is secured with a pair of
Torx screws smaller than I have a driver for, so I will have to report
on their internals at a later time.


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