Tracking mount (Barn door)

Has anyone successfully made a motor driven Barn Door tracking mount?

I've seen a few spec sheets on the net, but really, they are not very good a detailing what needs doing or what parts to use etc.

967stuart wrote in post #16280877
Has anyone successfully made a motor driven Barn Door tracking mount?

I've seen a few spec sheets on the net, but really, they are not very good a detailing what needs doing or what parts to use etc.

HERE is a good article, see if this can help.

I've built a couple of mount tracking systems.. including the one supporting my 12" (dual stepper drive)

If you find yourself scratching you head over any detail, especially electronic, drop me a PM, I can't guarantee I'll have an answer but there's always a chance.

Derek

Thanks guys.

Got one (probably silly) question...

I've seen it mentioned a couple of times that it needs to be polar aligned, Can anyone explain to me the reason for this?

Is this to just get the mount in the correct position? then I can swivel the camera to where I'd like to photograph?

The purpose of the barn door is to compensate for the earth's rotation.

To achieve this the barn door needs to be precisely aligned to the rotational axis of the earth. The celestial poles are the rotational axis indicators.

Once the barn door is polar aligned, you can point the camera in any direction you like.

http://www.clarkvision​.com …barn.door.track​ing.mount/

ETA

http://homepages.nildr​am.co.uk …oor%20NCP%20ali​gnment.htm

The hinge should point to the polar star, meaning that the hinge is aiming in the same direction as the axis earth is rotating around.

This allows the barn door to open (or close), creating a rotation that can negate the rotation of earth. There is a big offset error since the barn door and camera is a long way from the center of the earth, but for other stars this distance doesn't matter because of the huge distance to the stars.

So in the end - by having the barn door polar-aligned, you can cancel out the earth spin around its own axis and thereby stop the star field from looking like it is spinning around. The earth rotation around the sun will still happen but the distance that earth moves in an hour is still small compared to the distance to the stars. It's just the spin around it's own axis that must be cancelled out.

Ah I see, thanks folks.
There's a lot to learn!

It's turning into a real head scratcher as none of these guides really go into great detail.. as in - motors to use.. how to power them etc. (as not everyone has a working knowledge of circuitry, gearing and soldering! lol)

I'm really surprised someone hasn't put together a 'hobby kit' to sell on ebay or something.
Surly there is a market for this type of thing.

*If by some miracle I manage to put this thing together (and it actually works) I will do 'dummys' guide, with links to motors, parts etc..

967stuart,

have you looked at this website?

http://www.garyseronik​.com/?q=node/52

I have thanks Steve, it's a helpful guide, plus there's a proper parts guide!
Will order up some bits and see how I get on

I too was interested in a barn door tracker and in my research came across these sites, from the same gentleman.

http://www.youtube.com​/watch?v=2H3JDUzTksE

http://www.flickr.com …r/sets/72157632​174760809/

He's very knowledgeable, loves to talk about star trackers, and I believe he may have some components for sale.

Ive been wanting to build one of these recently (without a motor). I will give that a go first to see the results. Would be interested in your "how to" if you build a motorised one

alliben wrote in post #16285182
I too was interested in a barn door tracker and in my research came across these sites, from the same gentleman.

http://www.youtube.com​/watch?v=2H3JDUzTksE

http://www.flickr.com …r/sets/72157632​174760809/

He's very knowledgeable, loves to talk about star trackers, and I believe he may have some components for sale.

That's awesome thanks.
Following on some of his links, it does indeed look like he sells some of the parts.
I've already purchased some parts (from ebay) so will see how I get on, if it doesn't pan out, I will look to get some parts from him.

Looking into the parts that guy sells, he seems to be using a stepper motor which needs a circuit board to 'pulse' to give the correct 1rpm....

I've been looking down a different path.
I was looking to be buying a small voltage motor and use a power control to throttle back the rotations... I'm not sure if these power adjusters are that good that they could pull it back sufficiently ?!?

Got a feeling that whether I like it or not, I'm going to be learning a lot about motors and electronics.