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Electronic Kiwi

Member Since: July 27, 2010

Country: New Zealand

  • Guys, that is not what I meant when I said to make sure you include a stackable header in the shield design!


    Yeah, I know - where is the fun in that!?!

    Instead of motorising the pan and tilt axes on the scope, which will require knowledge of where you are and what you want to point it at, you can make a far simpler single-axis drive, similar to an equatorial mount. You also don't have to modify the telescope (much)!

    A Dobsonian Wedge (or equatorial wedge) is a platform that your telescope sits on. The platform is angled according to the latitude you are at (so if you stay in one town you can make a fixed-angle platform). You align the platform to north (or south if you are in the southern hemisphere like me). Perhaps glue a compass to the base as there is no star like North Star at the celestial south pole. The platform has one rotation axis aligned to north and sloping at your latitude angle, so points right at the north star. You then have a drive (at a constant speed) rotating the platform around that axis - just like with the standard EQ mount.

    You don't have to modify the telescope, except that some rotation brakes will be needed to keep the telescope pointed at the object you are looking at, particularly as the whole base will be on a sloping platform - depends how loose your bearings are. Depending on your latitude you might also want to have some clamps or similar to hold the telescope onto the platform.

    The big disadvantage is that, depending on the size of your platform, the rotation might only last for an hour or two, then you have to "rewind" the platform back to the beginning. A fast drive option is handy for that.

    I've been thinking of doing this with a worm drive driven by a stepper motor. A switch selects normal speed forward or fast speed rewind. A trim pot would allow for tuning the forward speed to the earth's rotational speed. A limit switch at each end of the travel.

    The big disadvantage of Dobsonians for astro-photography is that the eyepiece also needs to rotate, and both mounts have that issue. Another stepper to rotate the camera in the eyepiece holder is desirable for either method.

  • If I mounted this board vertically could I get a Z-axis gyro rate, or does it not work that way?

  • Now, I just need to connect the BlueSmirf module and I'll be able to encrypt the entire Internet into Norse code and achieve total world domination! Mwuuuhaahaahaaaaaaaa.

  • Wow, that shock from the EL inverter must have scrambled my brain - I keep seeing a cow in the hallway!

No public wish lists :(