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  #61  
Old 12-11-2018, 01:05 PM
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The UK website suggests using the green laser pointer for aligning..

I think you can do the same in Queensland (we in VIC need to have license for succh lasers).

I would use red dot finder, or one of those polar finders(they are too expensive IMO)


BTW, Red Dot Finder (RDF) is very useful for aiming at objects on the shy...
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  #62  
Old 12-11-2018, 09:54 PM
Jasp05 (Aaron)
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I found my old tracker. Picture attached.

I attached my ballhead to the bolt on the top plate closest to the hinge. (the closer the camera is to the hinge the sturdier it will be and it makes it easier for the stepper to drive the weight up as it follows the sky.)

This was a 3/8 inch bolt in my case as my ball head could take either a 1/4 inch or 3/8.

The threaded rod was bent by printing out the required radius on A4 paper and then bending the rod by hand. I believe a curved rod will stay tracking better for longer than a straight rod.
I used a 1 mtr length and grabbed it by both ends and bent them in to get the curve. If you grab a short length to bend you will just make a a very sharp odd shaped curve instead of a nice round even curve. the middle of the 1 mtr length will have a decent curve (You only need 200-300mm at most in the centre). Everything else either side will still be to straight to be of use.

The gear on the threaded rod was just a kit from Jaycar electronics. Was like 10 bucks for about 6 different gears which all fit on stepper motors. So I used a small spur gear on the stepper (which is missing in the photo).

The larger gear was drilled to slightly under the diameter of the nut to suit your threaded rod. Then I just hammered the nut into place in the gear. Its stuck in there quite nicely just like that. (I put a thrust bearing under this gear to reduce friction against the base board. Probably not required but for an extra dollar or 2 it seemed worthwhile).

The only important thing about the gears is the ratio between them as you need that to calculate the RPM required from the stepper motor. and the larger the ratio the more torque can be applied to the drive rod. (I tested my setup and it was pushing around 2-3kg easily when weight was placed directly over the drive rod. so 2-3kg at the camera mount point was even easier). even though my camera setup weighed somewhere around 1kg at the time.

Hopefully this was helpful. If you need a hand with coding an arduino to drive the stepper, I'm no expert but can bumble my way through it enough to help.
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  #63  
Old 13-11-2018, 07:31 AM
Jethro777 (Jethro)
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Thanks Aaron,
That picture does help. I have to say I am very nervous about ordering a motor. I'm worried it's going to be the wrong speed, or that I have trouble attaching it because it is the wrong shape. It's not much though, so I may order one today that I can run on a 6v. AC worries me (electrocution), so it definitely needs to be DC.
Also, I need to get some gears, the middle part of the gear, how do I know if it will fit into the motor?

Can anyone recommend/link a motor (DC) and the gears that should be workable?

Thinking this one? : https://www.ebay.com.au/itm/DC-6V-1r...AAAOSwH05ZsLCx

I don't think I want any electronics/programming on it.

I have found a supplier of gears, just not sure what to match up. (https://www.ebay.com.au/itm/Various-...HstQ:rk:1:pf:0)

I took out the camera for a test run last night at 135mm with a Minolta 28-135, which is truly an exceptional terrestrial lens - but it's a disaster for Astro.

This has really made me appreciate the 100mmm f/2.8 prime I am using, which flattens so well and is free of chromatic aberrations..

First shot is with a UV filter on the front (forgot to remove it)
Then, without (not that it really helps given that lens).
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  #64  
Old 13-11-2018, 07:43 AM
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Jethro, for DC motor you will need more complicated servo electronics, to stabilise rotating speed.

Arduino controlled stepper is a good and very versatile aproach - but a bit more complicated, and I have a feeling you are not comfortable with hands-on to those things... that is why I suggested AC motor with (or without) transformer.

If it is "wrong" speed (50-60Hz issue) this is easily mitigated with suitable dimensioning of the mechancal design (the whole thing on UK website you mentioned earlier is designed such that you have to turn the knob once per minute, listerning to 5-sec beeps (and moving handle by 30) or watching the seconds hand of your wristwatch)


Good source of gears are old trashed printers, scanners etc.
Also you can try Small parts,they have a lots of other stuff.


On your latest pictures - I think they are out of focus. You may want to use Bahtinov mask to achieve better focus.

Last edited by bojan; 13-11-2018 at 08:15 AM.
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  #65  
Old 13-11-2018, 09:25 AM
Jasp05 (Aaron)
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Quote:
Originally Posted by Jethro777 View Post
Thanks Aaron,
That picture does help. I have to say I am very nervous about ordering a motor. I'm worried it's going to be the wrong speed, or that I have trouble attaching it because it is the wrong shape. It's not much though, so I may order one today that I can run on a 6v. AC worries me (electrocution), so it definitely needs to be DC.
Also, I need to get some gears, the middle part of the gear, how do I know if it will fit into the motor?

Can anyone recommend/link a motor (DC) and the gears that should be workable?

Thinking this one? : https://www.ebay.com.au/itm/DC-6V-1r...AAAOSwH05ZsLCx

I don't think I want any electronics/programming on it.

I have found a supplier of gears, just not sure what to match up. (https://www.ebay.com.au/itm/Various-...HstQ:rk:1:pf:0)

I took out the camera for a test run last night at 135mm with a Minolta 28-135, which is truly an exceptional terrestrial lens - but it's a disaster for Astro.

This has really made me appreciate the 100mmm f/2.8 prime I am using, which flattens so well and is free of chromatic aberrations..

First shot is with a UV filter on the front (forgot to remove it)
Then, without (not that it really helps given that lens).
I wouldn't stress too much over the electronics. Its plug and play with the wires. (Don't have to solder anything). wires just push on/off. I use hot glue to stop them falling out. (see picture below).

It's 2 power wires and 4 signal wires for controlling the stepper motor. The stepper motor has a cable harness which will plug into the driver board. (the driver board comes with the stepper when you buy it and is the little green board).

Only thing you really need to do is plug a usb cable into the arduino and "upload" code to the board. All you do is install the Arduino program on your desktop. There is plenty of code online or I can help with writing something that you copy paste into the window. Then hit upload. And its done.

And the best part is the whole thing is just slightly bigger than a credit card when put together.
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  #66  
Old 13-11-2018, 02:12 PM
Jethro777 (Jethro)
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It looks like working with the arduino won't electrocute me.
If I went this way, I would need the arduino board (there are several, right?), and some bits (motor - a little blue one will do it eh?).

Perhaps I could find a motor in a printer or broken scanner. I'll see what I can come up with.
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  #67  
Old 13-11-2018, 02:23 PM
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Quote:
Originally Posted by Jethro777 View Post
It looks like working with the arduino won't electrocute me.
If I went this way, I would need the arduino board (there are several, right?), and some bits (motor - a little blue one will do it eh?).

Perhaps I could find a motor in a printer or broken scanner. I'll see what I can come up with.

Printers andd scanners are full of motors and gears :-)

However, they may be bipolar, and that little motor with driver from ebay is only 2$ (plus waiting to arrive from China.. I bought 5 some time ago and used them all) and it is what Aaron proposed (to be used with Arduino Uno, as pictured).
Also, you can get 3 Arduino Nano boards for 10$... (Nano is smaller but uses the same processor)
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  #68  
Old 13-11-2018, 02:28 PM
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Quote:
Originally Posted by bojan View Post
Printers andd scanners are full of motors and gears :-)

However, they may be bipolar, and that little motor with driver from ebay is only 2$ (plus waiting to arrive from China.. I bought 5 some time ago and used them all) and it is what Aaron proposed (to be used with Arduino Uno, as pictured).
Also, you can get 3 Arduino Nano boards for 10$... (Nano is smaller but uses the same processor)
Can you link these please Bojan?
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  #69  
Old 13-11-2018, 04:31 PM
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Sorry, my mistake, it was 3 for 9$ each..
https://www.ebay.com.au/itm/3-5-10-P...vETw:rk:7:pf:0


steppers:
https://www.ebay.com.au/itm/28BYJ-48...:rk:5:pf:0&var


Stepper is powered from 12V, so you need 5V regulator for processor board as well:
https://www.ebay.com.au/itm/0DB1-5V-...2755:rk:5:pf:0

https://www.ebay.com.au/itm/1-2-5pc-...:rk:5:pf:0&var
https://www.ebay.com.au/itm/78L05-5V...xnm:rk:95:pf:0

Last edited by bojan; 13-11-2018 at 04:42 PM.
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  #70  
Old 13-11-2018, 04:39 PM
Jethro777 (Jethro)
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Thanks Bojan! Ordered.

1 x Nano V3.0 MINI USB ATmega328P CH340G 5V 16M Micro-controller Board Arduino
1 x 28BYJ-48 2003 Stepper Motor Driver Module For Arduino
1 x DC 5V Stepper Motor
1 x 0DB1 5V Out 6V To 12V In Step Down Linear Voltage Regulator Power Module Board

Now, let's see..

Solder iron? Check.
Wire stripper? Check.
Wires, nope.
Solder, nope.

Few other bits I'll get and I'll be right thanks to those arduous wait times... Hinges also arrived today.
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  #71  
Old 13-11-2018, 04:45 PM
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Don't forget 12V -> 5V regulator
https://www.ebay.com.au/itm/0DB1-5V-...2755:rk:5:pf:0
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  #72  
Old 13-11-2018, 04:48 PM
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Added, anything else?
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  #73  
Old 13-11-2018, 04:51 PM
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You need Arduino IDE:
https://www.arduino.cc/en/Main/Software
And some sketch to start with
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  #74  
Old 13-11-2018, 04:57 PM
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You may need something to couple stepper motor to threaded rod (like this below, check the diameters - stepper shaft will be 5mm, your threaded rod will be something else)

https://www.ebay.com.au/itm/19-25-mm...WEg:rk:13:pf:0


Or, do it like Aaron did.


BTW, bent threaded rod is OK because tracking speed will not change as the barn door opens.. but straight rod can also be used, the necessary change in speed can be achieved in the program (called "sketch" for whatever reason..)
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Old 13-11-2018, 04:59 PM
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I will definitely need some gears.
And yes, something to attach to the rod. The rod is an M6.

Bojan, I take it that I only need ONE of these - they are both the "same" voltage regulator, right? What does this / do they do? What/where do they attach onto? Do I need a "bread board" I think they call it?

So that I've got things right;

1 x Nano V3.0 MINI USB ATmega328P CH340G 5V 16M Micro-controller Board Arduino

Base board.

1 x 28BYJ-48 2003 Stepper Motor Driver Module For Arduino

Needed to run the motor, obviously

1 x DC 5V Stepper Motor

Actually moves things.

1 x 0DB1 5V Out 6V To 12V In Step Down Linear Voltage Regulator Power Module Board

Allows me to run the thing using 6v instead of 12V?

Software "Sketch" - to transfer the program to the board + USB Cable (got that).

https://www.ebay.com.au/itm/19-25-mm...WEg:rk:13:pf:0
It allows me to couple the stepper motor to threaded rod - how exactly?

Last edited by Jethro777; 13-11-2018 at 06:13 PM.
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  #76  
Old 13-11-2018, 05:32 PM
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And USB cable...
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  #77  
Old 14-11-2018, 06:04 AM
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Here you can find the code for tracker:
https://kukuruku.co/post/diy-an-astr...in-two-nights/
(some parts of it are not necessary as they are for LCD)


Another one:
https://www.jjrobots.com/projects-2/startracker/


Google search results in many more projects like those...
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  #78  
Old 14-11-2018, 10:35 AM
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Jethro that Arduino board will operate from 12v just fine. Its input voltage should be between 5-12v. (It's regulated on the arduino pcb).

It's logic level is 5v. Which means its output signal to the pins is 5v. Which is neither here nor there when operating that stepper.

So just connect to a 12v battery/ power source and you will be fine.

The stepper will also run off 12v but they run hot. So if you can best option is a pack of 4x aa batteries running the system. This gives you 6v which is enough for both stepper and arduino without having to worry about dropping the voltage. (one less thing you need to do).
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  #79  
Old 14-11-2018, 10:41 AM
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and are you doing straight or curved rod design Jethro?

My advice is curved rod. Bit more work to bend it and get the curve right, but it was easier for me to do that than try and code for the speed increase that will be required over time on a straight rod design.

with the curved rod, we can program it to just do 1 rotation per minute. (provided your gears are 1:1 ratio. if its different we just speed up or slow the stepper down which is a simple case of changing one value in the code).

I'll go home and have a play as I have all the parts you have purchased. I'll write something to get the stepper going 1 rpm so all you have to do is upload it if you like. (If you want the learning experience then by all means go for it).

Also with those CH340G arduino boards (their chinese clones of the original arduino) you will need the CH340G USB driver for your version of windows. Otherwise windows will not detect it when you plug it in.

What version windows do you have? I can find the download site, as their normally in chinese. A quick google search for "Arduino ch340g driver" will probably get you in the right place also.
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Old 14-11-2018, 01:38 PM
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I am thinking curved.
I have windows 10.
So basically, I probably don't need the voltage regulator.
Do I need to get some wires and solder? Bread board project box or similar?
Now for the long wait for parts.
I am currently imaging the LMC as well as orion and I have noticed I can do far longer exposures for the LMC because of the much closer proximity to the southern pole. Fascinating!
It's huge. I didn't position the LMC correctly as I didn't know it was so large and the orientation isn't perfect, but the 100mm lens seems just right.
This is going to be a new favourite of mine to image.
Wow.
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