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Smaller than a pound coin !


Guest peepshow
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Guest peepshow

Here is a stepper motor control board with a £1 coin. 

 

It can step full step, 1/4 1/8  or 1/16. 

Voltage up to 35v and current up to 2 amps.  Clocking input and direction control.

  

All smaller than a pound coin and cost no more than 5 of 'em. :)

When I ordered this I never realised how tiny things are getting. 

 

 

 

12610189735_18e2616c18.jpg
 

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Guest ecopley

Sure you already have this covered but don't forget that, for any kind of useable output you will need a heat sink. The magic smoke is crammed in really tightly and is desperate to get out!

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  • 3 weeks later...

Richard, hi again


Just replied to another thread of yours 16x stepper motor. The little Rep Rap board off ebay is what I use. Amazing aren't they! For my control pulse I use a noise maker circuit from Maplins. Great fun muckin' about with this stuff.


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Guest peepshow

Alan, I am now using an Easydriver board (£10 from UK and £2.55 from China !!!),


 with a stepper motor of low resistance.


What is the fastest speed you have managed to get I wonder?

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Hi Richard. I've never tried to run my motor at more than 1 or 2 rpm. That was when I was running the worm and gear in with grinding paste to try and improve the periodic error. The worm is held onto the gear with a spring so I just disengage it to return the mount  to the start position. It's only a part gear and can do about 3 hours before It runs out and has to be manually returned to the start of the sector.  


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Guest peepshow

Am I right in assuming that you have built your own eq. mount, Alan?


If so, you should post details here on this forum as many are interested in DIY to the stars. :)

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Yes that's right. I don't have a blog or site I can post a link to. Do you know if it's possible to put photo's into a post? I can describe it but a picture's worth a thousand words!


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Richard. You have no need for micro stepping your motor. I did some experiments before I started my eq tracker project and found I could get away with a 1/2 second exposure with a 400 mm lens on a APS C chipped camera. ( Nikon D300 ). I figured from this that as long as I stepped the mount at a rate of 2 per second I wouldn't have any visible streaking. Am I right in thinking that your step rate is 200 per sec? If so your step resolution is never going to be a problem.

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Guest peepshow

Alan, here is a link to thread on posting images from flickr.  

As I understand it, one cannot upload phots to this forum directly from your own PC. 

 

http://www.eastmidlandsstargazers.org.uk/topic/7354-how-to-share-images-from-flickr/?hl=%2Bflickr+%2Bimages

 

OK on stepping.  I can now reverse at x16 so that's OK.  Actual tracking has never been a problem, justn the mechanics

of rotten hinges. :)

 

Bringing in the other thread.....I do have photos of the old tracker but will soon be posting shots of the new improved one.

Old photos here...........  It is unusual in that it has an mini eq mount on it with digital read outs for RA and DEC.

 

i10739146124_4f2f9c35a0.jpg

 

Edited by peepshow
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Hi Richard.


That is an amazing bit of kit. Ingenious!


 Just joined Flickr and put some star tracker pics on it. Hope it works.


The RA axis uses an old rear wheel hub off a mini. The tripod is welded up from bits of scrap electrical conduit. The sector is fabricated from iron strip with a length of MOD .5 Rack bent around and welded onto the curve. The worm is a length of 16 tpi x 5/8 Whitworth studding. Stepper motor came from ebay. 


 


], on Flickrtos/119738074@N05/13013785224/'>13013785224_24f9fa65aa.jpg


Edited by Werisit
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Love both projects - More pleasure than just throwing money at it - Looks well engineered - Both deserve a pat on the back  :notworthy:


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Guest peepshow

Well Alan, I am very glad you were able to post that picture as it really made my day.


A great piece of astro DIY you have done there.


 


I was very interested to see  your DIY, RA mount, especially the worm and wheel,


which gave me a weird sense of daja vu.........


............many years ago I made a 10 inch worm and wheel using a picador pulley wheel. 


Into its groove I bent a length of 3/8 BSF threaded rod, pinning it as it went.  


This was for a manual eq mount too.


Then, just like yours I used more threaded rod as the worm mounted at a slight angle,


and again like yours, it was spring loaded.


They say great minds think alike.....great DIYers also :)


 


  As I said, my picture is out of date, all been redesigned and now


   using ball races on silver steel shafts, pre loaded.


 


You did mention periodic error and I wonder if you have this at all?


 


You will most certainly know, that main bearing you used, which I take was used to machine


the wheels radius should have nil float.


Also how accurate does the rack fit the curved surface? 


Both can lead to mis shapen stars at best, especially with long focus lenses.  It looks, from your piccy that


you are not using any telescope, but just a camera.  I wonder what lenses you have and what


exposure times you have achieved?


 


Well Alan, this thread is getting off topic so before the moderators, moderate, I will stop. :)


Maybe we should start a new DIY thread sometime to compare notes further?

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Hi Richard,


Thank you for the compliments. It's very interesting to hear how you made your worm and wheel. Very inventive. 


You now have me thinking. Yes I have periodic error and presumably that is why you went the barn door route. I agree we should start a new thread as the title of this is no longer accurate so won't allow anyone to find it. There is much more to say on the subject. I too have a "mk 2" in progress!


How does one start a new thread?


Edited by Werisit
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Guest peepshow

Hi Richard,

Thank you for the compliments. It's very interesting to hear how you made your worm and wheel. Very inventive. 

You now have me thinking. Yes I have periodic error and presumably that is why you went the barn door route. I agree we should start a new thread as the title of this is no longer accurate so won't allow anyone to find it. There is much more to say on the subject. I too have a "mk 2" in progress!

How does one start a new thread?

To start a new thread select the section one wishes it to be in and hit start new topic button.

I will start a new one now in the DIY and mods section.  I will call it,' DIY mounts.'

Might see you there. :)

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