Re: [APML]: Byers drive and the MototrakIV

[Steve Bell <sb635@delphi.com>]

Mike Regish wrote:
> 
> 
> Interesting...and a whole lot cheaper than a new motor. How many wires
> does the JMI motor have? This thing has 6 wires and a flat 6 pin female
> connector. Any idea if all those wires are being used? They must be
> there for something. I figure they might be there for the various rates
> or something.
>

The simple JMI DC motors have just two wires, one for plus and one for
minus.

> Could be a problem if I wanted to hand hold the corrector with that
> transformer hanging off it, but I could tape it on with duct tape or
> something.
>

When I plugged in the transformer, just the friction of its prongs in
the MotoTrak's plug held it in pretty good. Weight wise, it shouldn't
hardly be too much of a difference with it as compared to without it.
Also, I don't actually hold my MotoTrak - I put it on the ground, and I
use a remote hand unit that plugs into the CCD telephone jack at the
bottom. But then, you might ask, where does the autoguider plug in?
Well, I made up a two-female to one male T-shaped connector. You can
find these for 4-pin telephone wires at Radio Shack, but they don't seem
to carry the 6-pin variety, which is what you need for the MotoTrak. The
CCD is plugged into one side, and the hand controller into the other.
Never, in operation, do you need to have the both of them sending input
to the MotoTrak at the same time, so that's not a problem.
 
> Any idea if the rate of the motor was right or any reason to think it
> might not be?

It turned the JMI DC motor at the rate it runs at when getting 12V. When
the fast button was pressed, the MotoTrak increased the Hz (went up to
100 Hz from 60 Hz) of the AC coming out of its 110V plug, and then
apparently the 110V AC to 12V DC transformer put out more than 12V, and
the JMI DC motor ran faster. When the slow down button was pressed, the
MotoTrak puts out 20 Hz, and the transformer apparently puts out lower
than 12V, and the DC motor slowed down. That's the part I didn't know
would happen or not. I assume your stepper motor runs at the right rate
to rotate the big 11 5/16" gear at the desired sidereal rate when
supplied with 12V DC. I'm pretty sure just putting a 110V AC to 12V DC
transformer between it and the MotoTrak will give you that, although I
don't know if it will have enough power to turn a whole scope. What I
didn't know was what goes on the the Hz coming out of the MotoTrak was
increased and decreased, but my experiment shows that works too. Or at
least it does speed up and slow down a simple DC motor.

-- 
Clear skies,
Steve Bell
email: sb635@delphi.com
Astrophoto page: http://people.delphi.com/sb635