Digital Setting Circle Computer - Page 2

jeroenhmg (Jeroen) · #21 09-02-2010, 02:10 AM

isn't it easier and cheaper to just buy BETI from Astro Devices if you're planning to use Bluetooth? Here's a link: http://www.astrodevices.com/products/products.html

Best Regards,
J.

mbirrell · #22 09-02-2010, 06:23 AM

Hi Jeroen,

Yea it looks as if that would be a cheaper way to do things if you want bluetooth straight up. Not a bad price for what you get I recon.

mbirrell · #23 09-02-2010, 10:41 AM

My main plan is to mod a Meade Dobsonian to take a Encoder wheel without drilling any extra holes in the telescope's mount. Also I would like to make an encoder wheel that is cheap and accurate. My final mission is to enable just about anyone who has a Dobsonian to implement a push to system with minimal skill and cost.

Please be aware I have not tested most of the stuff I have written about yet but in the up and coming weeks I hope to provide photos and diagrams explaining everything.

Here is where I am up to so far...
I think I have gone through the difficult part of designing a cheap encoder wheel that will suffice the average amateur astronomer - all it is really is a 2,000 step encoder wheel printed out on an overhead transparency and the use of old mouse wheel sensors to send the ticks to Dave EK's box - no big deal.

Now for the trick of mounting the encoder wheels and sensors on the scope without hacking it up...

At the base of a Meade it has a 2 1/4" x 5/16" Hex Pivot Bolt - If I replaced that with a Tee (A nut designed to be driven into wood to create a threaded hole), a 3 1/2 inch long hex bolt and 3 nuts then I would have a way of securing the Encoder wheel in a fixed and central position.
The alt encoder wheel should be just a matter of getting double sided tape (Jacar cat no. NM2821) and placing it on the alt axle making sure that it is centered correctly.
The sensors for both will have a bracket that will be fixed with double sided tape. Wiring will be cable tied and held in place by the use of adhesive tie mounts (Jaycar cat no. HP1195). The Dave EK box will be held in place by (you guessed it!) double sided tape.
All in all I am hoping it will look as neat as I imagine (I am an Electrical fitter mechanic by trade and like doing a good job).

Lets see how I go...

mbirrell · #24 28-02-2010, 06:12 PM

Gee I thought SMD soldering would be a piece of cake... till I tried

bojan · #25 28-02-2010, 07:01 PM

Quote:

Originally Posted by mbirrell

Gee I thought SMD soldering would be a piece of cake... till I tried

It is.. But it requires somewhat different approach.
Instead of soldering iron and solder wire, you should be using solder paste (Jaycar) and hot plate (cooking appliance).
Microscope (or at least large lens) and precise tweezers are very helpful for placement of SMD components

mbirrell · #26 28-02-2010, 08:34 PM

yea after watching YouTube videos I discovered that is they way to go.
I however have only got a set of head mounted magnifiers, a lot of flux with a 1mm soldering tip and a tiny bit of solder...

The rest of the project is going quite well but it is a very slow journey.

bojan · #27 28-02-2010, 09:47 PM

This looks like a reflective module to me

I was supposed to get my PCB yesterday..

mbirrell · #28 28-02-2010, 10:04 PM

Yea it is - one of the types that you suggested. I am going to try an encoder wheel that has been printed on a laser printer. I got the PostScript from: http://www.thingiverse.com/thing:1527 to generate it.
All in all the most work I have put in is with the circuit board - I recreated it in FreePCB. To print it out I used ViewMate (not very user friendly). Then I used this paper called Etchatron to transfer it to the PCB. I think I could have used HP Glossy Laser paper though (a little bit cheaper). All the electronic components I got from Farnell.

mbirrell · #29 11-03-2010, 09:01 AM

Well last night I got my Dave EK DSC going at last!
I have got a bit side-tracked lately as I have been working on making a CNC machine. I figure this will help me make certain parts for this project and others to come.
Back to the Dave EK board - I was a bit worried for a while that the hard to get parts that I subsituted on the board wouldn't work - but they did! Also when I programed the PIC and put it in the board it didn't work either until I selected the correct clock to use (the crystal one and not the internal one!). I think that this part of the project would have been much easier if I had have taken up the offers of people making the board for me for a few bucks extra but I just have to play with fire