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How I Motorized My Dobsonian Telescope
Well, I recently (as of November 2001) motorized my Dob. This mean that I am
able to have the scope automatically track the object I'm looking at. And with
the addition of some software on a laptop, I am able to tell the scope to look
for a particular object in the sky, and it will automatically find it and point
itself at the object.
I got the motor kit from
Tech2000, a reputable company I found on the web.
With the help of my brother Lynn, I did the necessary cutting and drilling to
mount the motors. You may know the old carpenter's saying "Measure twice, cut
once"? Believe me, we measured considerably more than twice before cutting into
my beloved telescope!
Below are some pictures of my scope with the motors. Next time I'm out in the
field, I'll get some shots of it in action, and maybe even a short movie of it!
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 | Here is a
shot of the entire scope. The slanted bracket with the holes in it is the eyepiece
rack that used to be attached to the side of the base, where the motor is now.
I put it on the tube so that the eyepieces would be closer at hand. I put it on
crooked, since the scope is usually operated with the tube somewhere near a 45°
angle. This way, the rack is closer to horizontal, and the eyepieces don't fall
out! (trust me on this) |
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 | Here you
see the altitude motor, with the belt looping up over the pulley. The pulley is
mounted on the right hand bearing of the original scope. This is what moves the
scope vertically.
The cables and wires that you see pass through holes in the sides of the base,
to keep them out of view (visible wires are so unsightly). |
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Here's a close up
view of the alt motor mount. The motor mount has a release lever that lets me
loosen the belt so I can manually adjust the tube without damaging the motor.
The release mechanism is below the motor. You pull up on the lever, and the
whole motor slides up, releasing the tension on the belt. You can then either
adjust the vertical position of the tube, or slip the belt off the pulley entirely,
allowing you to remove the tube from the base.
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Here is the azimuth motor.
This is what moves the scope horizontally.
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Here is a closer
shot of the azimuth motor. The knob you see to the left of the
motor is the release mechanism that allows me to manually move the scope sideways
without damaging the motor. By tightening the knob, a teflon pad is pushed against
the baseboard, lifting the knurled wheel of the motor off of contact with the baseboard.
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This is where the
wiring from the motors connects to the power supply and the control paddle. The
power supply (12 v battery, cigarette lighter adapter or AC power adapter) is
plugged into the light blue connectors you see at the end of the wire. The black
wire at the left leads to the control paddle.
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This is the control
paddle. Here I have it mounted to the alt pulley with velcro. I have additional
pieces of velcro stuck to the tube near the focuser, and on the side of the base.
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 | Here is a closer
shot of the control paddle. The 4 buttons are used to select which function will
be used (tracking, manual slew, etc.) They also control the manual slew. The
white square (marked "PC Link") is where a cable from a personal computer can be
connected, so that the astronomy software on the PC can be used to control the
scope. There is also a spot (marked "CCD Link") where a CCD camera can be
connected. This would allow the CCD camera to track the object in view, rather
than the PC or the control paddle. Tech2000 doesn't have this feature available
yet, though. |
UPDATE: October 29, 2003
It appears that the weight of the sonotube material (the cardboard-like stuff
the tube is made of) is too heavy for the motors. If I have any weight
on the scope (large eyepieces, spotter scope, counterweights) then the azimuth
motor binds up. It will run a few inches, then stop with a whining noise.
I'll look into maybe getting a lighter-weight tube at some point, but right now
all my attention is on my new 25 Obsession
(for obvious reasons!) |
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