10" dob, stepper motor for focus and movement

[netwolf]

Dave do you mean computer/motor polar alignment? Well following your two star alignment process, assuming its posible to locate the pole using the DSC or computer. You would then manualy adjust the buggy such that your telescope when pointing at the pole is perpendicular to the plane of the wedge. Pointing straight up on the tilt.

[davidpretorius]

yes computer polar alignment

i agree, just as long as you can lock and unlock the base, you don't want the scope moving off the pole as you adjust the base to suit

[netwolf]

Dave if you could interface the USB stpper controller to a cheap PDA with USB that would be ideal. But that can get quiet expensive. With your system the computer weather a PDA or Laptop, is needed for Slew (goto) and Track in RA/Dec or Alt/az.
I am not sure weather in Bartel's stepper system the motors can at least track without the laptop. But i belive this is the case in the servo system where tha laptop is optional for Slewing (goto).

This is another alternative to Bartel,
http://cedrica.webpipe.net/tc.html
that does not need a computer for Slewing or Tracking. The computer is optional to add to the database of objects using a Sky chart application.


Dave i know for you the over the Internet controll aspect is important but am not sure this is the general requirement for all.

[netwolf]

I am not sure you can lock onto the pole with a computer? There is no star there, i have been trying to work out if there is a way to do this or not.

[davidpretorius]

yes no star, but with steppers and by starting the process in alt/az mode, you can locate a known star and enter the co-ordinates, then step to a 2nd star for a double check, then theoretically, you can move the x -y plane with the stepper to be spot on the pole as the system should know where it is. then you lift the wedge up.

i still want the system to be able to be hand controlled but the may be some features that i can't make without a computer. interfacing with a goto or other products with star databases is fine if i am able to get at the output signals of the goto and then make sure they run the steppers?

i want the system to be as flexible as possible and as cheap as possible at the end of the day

[davidpretorius]

also, i do not know the costs of these dedicated star systems, a lot of people are now getting laptops which they can use for more than just stars.

my gut feel is that if i was going to spend more than $200-$300 on a dedicated piece of hardware for stars, i would rather buy a laptop.

preexisting hardware like your link, i do not know how flexible they are, how friendly and accepting of different steppers they are etc?

i doubt whether it would like usb.

to build one from scratch would cost $1000's i would imagine.

[netwolf]

David the link i posted is for a DIY unit with full plans to build it and a full manual.
For Usb you can always add a usb to serial adapter. I dont think it would cost all that much to build that unit. I used a similar microproccessor and GAL chips at uni for our Microproccesor assignments, i dont recall it being very costly. However your right its not for everyone. The thing i like about it is that it can be used independetly or with a computer, you have the option. I reccomend you download the schematics and manual, to take a look.

That being said you are right about the trend to get laptop these days. I am using my laptop right now. Also having wireless on it gives me access to the web while using my scope. I can post directly to the fourms from my laptop, while using my CCD camera to view the stars. Especially with software like Astrovideo where you can do video integration of chip to show nebulosity on the computer screen for viewing.

[netwolf]

Also there is an emulator in the files so you can test the system as if you were controlling a telescope to see its operation before building it.

And Dave, there is some good information on the Math and how the unit calucaltes the positioning of the telescope form cordinates.

[netwolf]

Dave, i recived a response to post i made on Scope-drive groups. The gentelment who has sent me the link is the creator and author of the following link and device listed within.
http://martin-cibulski.de/atm/mount_...er_4/index.htm

[davidpretorius]

it has definate potential, once i have a prototype going on pda and laptop, i can then start looking at a hand held controller.

hopefully, it is a flexible system to allow for many combinations of equipment

[netwolf]

on closer inspection the curent version 4 of Martin's sytem does not have Planet tracking. It only tracks Stars etc.

[davidpretorius]

yes, it is a pity with custom built that this occurs. that is why i like to work with what should be around for a long time ie microsoft products. nowhere near the best in the world, but eventually they catch on to what is good!

i got a skf 51204 thrust bearing and a 150mm x 20mm stainless steel rod.

i am going to see how i go with this supporting the weight of the dob at say 50 degrees over the weekend with the bearing and rod. I also looked at chain and spokes for driving the dob.

i reckon i am about 2 weeks away from doing an initial test in alt / az mode!

i also came across a 12" lazy susan bearing for $10. it is great for the between the dob bases. really really smooth.

[netwolf]

Excelent news Dave, i am eagerly waiting to see how the rod holds up to 50 degrees.

I have found some more cool stuff
http://www.circuitcellar.com/avr2004/DA3760.html
Move over JMI Motofocus..

Also found this Australian electronics dealer for the AVR and other Microcontrollers etc.
http://www.dontronics.com/prod.html

The AVR is a new cheap microcontroller that is easy to program see here for samples
http://www.circuitcellar.com/avr2004/index.html
Everything from Internet MP3 tuners to a Servo Controller that can control upto 30 servo motors..

Here is where the AVR Freaks hang out
http://www.avrfreaks.net/