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General questions about MRotate

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DaOld Man:
I experimented with some steppers, but I could not find a cheap one that was strong enough to turn the 19" LCD monitor.
I did find one that came very close, but it would internally slip and loose counts, which meant the monitor would not stop correctly and would incrementally get farther off on each rotation.
I used the printer port and a homemade drive to fire the motor, and I wrote a MRotate version just for that purpose.

We use servos at work to move grinding machines in very precise moves (think CNC), plus OND has already used one on his monitor setup, but I gave up because the big servos are very expensive, and the drives for them can be too.
But I am intrigued by being able to adjust the stopping points, and the slow down points, and the speed all from the software.
Anyway, if someone comes up with a cheap way to do it, Im in! (Using servo or stepper).

(Im trying to find a pic of my test stepper setup, but I cant find any, they may have got lost when my hard drive crashed last year. I will have to see if I made a backup.)
Here are some cheap steppers:

http://www.allelectronics.com/make-a-store/category/400/Motors/1.html

They dont have the one I used anymore, but it had a gearbox that increased the torque quite a bit, and it still wasnt enough to correctly turn the monitor every time. (Steppers are prone to internal slippage under heavy loads.)

Edit: trying to create a short link to the allelectronics stepper motor category is not working. Sorry about posting the long link. Click on the link, then click on stepper motors on the website.

DaOld Man:
Ok, finally found time to search through my backups and here is the last experiment with a stepper motor:

I really thought this was going to work, but the 19" LCD was just too side heavy.

DaOld Man:
Here are some steppers I tried.
In first pic, the one on the left is the one I thought would be the keeper, it has a gearbox which increases the torque a lot.

Second pic was the wiring diagram. The transistors supplied the pulses to the stepper. I used opto-isolators to isolate the computer from the high current stuff. Cant remember why I put "dont use" on it..

Third pic is the front end of the rig, with the monitor removed.
I really liked the way the stepper worked, if it was just powerful enough.  I had a special Mrotate written that would allow me to set up slow down and stopping points. Of course the speed can be controlled by controlling how fast the pulses to the motor are, or how close together they are.
This is what inspired me to do a counter on a regular DC motor, and DarthPaul took that idea and made it work with his rotating panel. (Thanks Paul!)

DaOld Man:
Now I remember why I put "dont use" on that last schematic.
The stepper I was wanting to use had a parking brake on it. Only problem was that it was 24 VDC, so I made some changes to more safely handle it with the printer port interface.
This is the schematic I went with.
Notice I also implemented a SSR switched receptacle for the monitor, I posted a thread about that somewhere on here.


Edit: Found the thread to the ssr receptacle:

http://forum.arcadecontrols.com/index.php?topic=104682.0

darthpaul:
 :applaud: :notworthy:

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