Features
1. Single (surplus) stepper motor per axis.
2. Very simple drive circuit.
3. Smooth microstepping tracking. Here is a note from Chuck Shaw showing
how accurate the drive can be in a portable scope: "I went to our dark
sky location where we have the 32 inch Danciger newtonian and took my 14
with me to do some dark sky imaging. The drive system's performance was
breathtaking!!!! I took 21 one minute exposures of M-101 at f/3.5 (14.5
inch f/5 system with a .7 focal reducer). When I went to do the track and
stack operations, the TOTAL displacement from the first image to the 21st
image was only 13 pixels....!!!! That is about 30 arcseconds over the almost
30 minutes it took to take the images!!!! Thats a drift rate of about 1
arcsecond/minute!!!!!! Incredible!!!!!!!!!!!! Do I love this system or
what????"
4. High speed overvoltage halfstep slewing.
5. Low current draw, typically 0.1 amps at 12 volts DC.
6. 3 star init for more precise pointing.
7. Field de-rotation.
8. Backlash compensation.
9. Periodic error correction.
10. Refraction correction.
11. Computerized finding from a number of contributed data files, or
from manual entry of coordinates including offsets.
12. Tight integration with Project Pluto's DOS and Win95 versions.
13. Drift compensation, to track at lunar and solar rates, to follow
fast moving comets, and to null tracking rate.
14. Recording of multiple cycles of guiding corrections for later analysis
and on the fly conversion into periodic error correction.
15. Siderostat option: prevents mount from flipping over and instead
moves scope past zenith.
16. Altitude and azimuth software motion limits.
17. Recovery of last position and last orientation to the sky.
18. Move to a home position for blind storage.
19. Optional encoders so that the scope can keep track of its position
when moving by hand, including option to use the mouse encoders..
20. Real time display of all coordinates and status.
21. Robotic scrolling motions, best described as high magnification
'fly-overs'.
22. Grand tour, where a flip of a switch takes you from object to object
in a data file.
23. Ability to record scope position from the eyepiece, for later use
in data files.
24. A number of test options.
25. Can receive LX200 protocol commands from an external PC running
any of the popular planetarium programs.
25. Ability to automatically reset the coordinates in preparation for
a German Equatorial Mount flipping across the meridian.
26. Automatically refines the altitude reading based on the initialization.
The disadvantage of this system is that you need a PC or laptop. However,
you can buy used 486 machines for as little as $100 (see http://www.onsale.com/category/Desktop_Computers.htm).
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continue onto 'Mechanic Aspects of the Drive'
...by Mel Bartels