24vdc motors + Duemilanove = umm...

[Matt Gilbert]

I've been powering 24VDC stepper motors salvaged from scanners with
the Arduino Duemilanove. It has a USB/powerjack switcher that is not
handled by a jumper but by some component. Here's the catch:

I haven't managed to get it to drive the motors correctly unless the
USB cable was also plugged in. The larger voltages lead to
unpredictable/unstable behavior unless USB is plugged in. Anyone run
into this?

[John Weiler]

What have you been powering it with? I assume a wall wart of some sort
but what voltage? I have not used the duemilanove but I know the
diecimila likes an input voltage that is relatively low. Not 24 volts.
In order to control large stepper I would think you would need a relay
of some sort.

There are a few other ways to handle steppers besides supplying voltage
directly from Arduino but you may have already considered that.

John

[Matt Gilbert]

a 24VDC 400mA wall wart. I know, it's a bit beyond spec, or at least
right at the edge, but relays have proven very unreliable in my
experience. tried a transistor-based approach once, but couldn't
figure out how to get that fully separated from the board.

matt

[John Weiler]

My guess is too much voltage is the problem. I think the recommended voltage is 7-12V with a MAX of 20V.

My main experience with steppers is PIC based CNC controllers but the approach will probably work if you are using bipolar steppers. I built several PICStep controllers (http://www.fromorbit.com ) They use a LMD18245 motor controller chip and can handle 55V 3A. It's probably not as easy as using the stepper library from Arduino but you can control larger steppers

Out of curiosity what are you building?

John Weiler, AIA
Architect
The S / L / A / M Collaborative, Inc.
1123 Zonolite Road NE, Suite 30
Atlanta, GA 30306-2016
d 404.853.5115 ext. 4102 f 404.853.5117
wei...@slamcoll.com
www.slamcoll.com

[Matt Gilbert]

A pretty simple task in terms of electronics. It's a sort of puppet/
stop-motion controller. A single step motor reels in or lets out
sewing thread tied to various objects, so they can be moved in very
small steps. Take picture, turn the motor a tiny bit, take a
picture...and so on. Trying to make stop-motion animations that in a
toungue-in-cheek way sort of resemble high speed video of explosions.

The PICstep stuff is very cool. Might open things up a bit...

Matt

On Jun 5, 10:16 am, "John Weiler" <Wei...@slamcoll.com> wrote:
> My guess is too much voltage is the problem.  I think the recommended voltage is 7-12V with a MAX of 20V.
>

> My main experience with steppers is PIC based CNC controllers but the approach will probably work if you are using bipolar steppers.  I built several PICStep controllers (http://www.fromorbit.com)  They use a LMD18245 motor controller chip and can handle 55V 3A.  It's probably not as easy as using the stepper library from Arduino but you can control larger steppers

[John Weiler]

You might also want to take a look at http://www.pminmo.com They have a bunch of other designs for cnc controllers including some for unipolar steppers

John Weiler, AIA
Architect
The S / L / A / M Collaborative, Inc.
1123 Zonolite Road NE, Suite 30
Atlanta, GA 30306-2016
d 404.853.5115 ext. 4102 f 404.853.5117
wei...@slamcoll.com
www.slamcoll.com