Hi,
There are quite a few threads on Barn Door trackers.
Here's one for Stepper motors.
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http://www.iceinspace.com.au/forum/s...d.php?t=101813
You may like to try a forum search for more.
The "Show us your equipment" thread has some interesting images too.
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http://www.iceinspace.com.au/forum/showthread.php?t=65