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Arduino Ascom focuser Mark2


tekkydave
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Thanks Gina and Dave for your confirmation on this, I will leave the Nano to derive it's power from the USB bus and power the ULN2003 directly via 13.8V.

I had previously noted an issue with the 5V motors in that I had to connect USB connect the arduino first and then connect the battery to get this to work correctly and drive the motor.

I've just completed the new bracket for the OO OC1 focuser and will complete the wiring for the temp probe tomorrow, now that I have a supply of 4K7 Ohm resistors.     The one wire and motor will be mounted at the bracket and connected back to my project box via a Cat 5e lead.   The project box will velcro to a power board on the pier, adjacent to the USB hub and DC power.

Pics to follow on completion - once the motor(s) arrive :)

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Actually, the Nano which uses the FTDI chip suffers this issue.

If you use the Nano powered by the CH340 chip, then there is no issue with the serial port and that Nano can be driven either using Vin or USB power.

The CH340 drivers are readilly available for Win/Mac/Linux

Cheers

Robert

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Up and running tonight - the one wire is returning sensible temps (19.5C) in the house and responds to warmth if I hold it.   I've taken the power (9V) direct to the ULN2003 and this seems to flash away on focus commands, but the 5V motor isn't turning at the end of the Cat5e cable.   I suspect this is simply the motor wires being a little too thick and not crimping well in the IDC's but will confirm tomorrow.    The bracket just needs a minor tweak to get the belt length and tension right - a little work with a file to allow some tension adjustment.

No sign of the 12V motors yet - wishing I had ordered these from the UK now, but hope to iron out the glitches and give this a try with the 9V supply and 5V motors, as Friday night is looking promising.

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As suspected the problem was the RJ45 sockets.   Although the old ITT-Cannon cat5 modules were small and neat, they were not properly crimping the motor wires, even after some gentle persuasion.  I have replaced both with TE cat6 modules and the whole unit now works perfectly.

I quite like the idea of data modules for the motor and one wire connections, as they are light and I can easilly swap around and choose patch lead length to suit.      Though it would make for a neater project if I could find some modules that soldered directly to 0.1" pitch veroboard.      Otherwise DB9 plugs and sockets are the usual way to go, but heavier, bulkier and not so neat to my mind.

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Finished my focusers for the rc and mak 127.Got a stainless pipe clamp from work and lined it with neoprene.Welded on a bracket.

I then got a few parts made at work for the clutch and drive.

Nice work - very neat job.
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Up and running tonight - the one wire is returning sensible temps (19.5C) in the house and responds to warmth if I hold it.   I've taken the power (9V) direct to the ULN2003 and this seems to flash away on focus commands, but the 5V motor isn't turning at the end of the Cat5e cable.   I suspect this is simply the motor wires being a little too thick and not crimping well in the IDC's but will confirm tomorrow.    The bracket just needs a minor tweak to get the belt length and tension right - a little work with a file to allow some tension adjustment.

No sign of the 12V motors yet - wishing I had ordered these from the UK now, but hope to iron out the glitches and give this a try with the 9V supply and 5V motors, as Friday night is looking promising.

Jake,

I am eventually interested in 12V steppers version.

I didn't found so many information about it.

Only one good tutorial for this stepper : http://42bots.com/tutorials/28byj-48-stepper-motor-with-uln2003-driver-and-arduino-uno/

And maybe an other well known article on Focus : http://www.astrodon.com/Orphan/parfocal_and_critical_focus_zone/

Didier S-C

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Jake,

I am eventually interested in 12V steppers version.

I didn't found so many information about it.

Only one good tutorial for this stepper : http://42bots.com/tutorials/28byj-48-stepper-motor-with-uln2003-driver-and-arduino-uno/

And maybe an other well known article on Focus : http://www.astrodon.com/Orphan/parfocal_and_critical_focus_zone/

Didier S-C

I sourced mine on ebay, via the slow boat from China http://www.ebay.co.uk/itm/12V-4-phase-5-wire-Stepper-Motor-Gear-Motor-28BYJ-48-12V-for-DIY-Project-XN-/271475220977?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item3f352f21f1

Should be a lot quicker to Beijing.

The directions in this thread are excellent, even for a relative Arduino newbie like myself.

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Only 12 days from China and £3.38 for both incl p&p!

5a3ab7aba086f37a9d067479df99a028.jpg

No complaints!

The 5v motor was working with the OC1, SX FW, TV x3 and QHY5L-II, but I think this should be a better solution and will all run from my 12v obs supply.

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My UNO board and motor shield work perfectly with stepper with motor. But one problem: my motor can not drive coarse focus knob of moonlite CFL focuser (it is quiet stiff), so I hook it to fine focus knob. However my imaging setup is slightly heavier than what it can handle so it does not rack in when the telescope points up. It forces me back to coarse knob.

Question is that: is there anyone using CFL moonlite focuser? And what motor do you use to drive coarse focus knob? I need to know so that I can get motor with enough torque.

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I don't have the same setup, but I opted to use a NEMA 17 12v/200 step stepper from the off - over engineering, maybe, but it's been a fun project, and gives very precise control via the fine focus knob, which is good for my Hyperstar setup due to the very narrow CFZ.

This certainly doesn't lack torque.

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I don't have the same setup, but I opted to use a NEMA 17 12v/200 step stepper from the off - over engineering, maybe, but it's been a fun project, and gives very precise control via the fine focus knob, which is good for my Hyperstar setup due to the very narrow CFZ.

This certainly doesn't lack torque.

I think I did not make myself clear.

My motor has enough torque to turn fine focus knob, it is the knob which fails to rack focuser in, I guess it just can not handle the load.

I need to find another motor to work with coarse focus knob - the current one does not have enough torque.

I confirmed with manual focus that coarse focus knob can rack in/out without any issue.

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Just got this on the scope, been waiting for the Sun to go too low as it's on the Quark scope and didn't want to disturb it 'till now.

Only running on the AAF2 app ATM, need to remount the scope and see if I can get it to work with Maxim.

Dave

post-21198-0-92531200-1419075144_thumb.j  post-21198-0-35186600-1419075146_thumb.j

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That looks good Davey, like the spring mounting, is that a door hinge you have used ?

No, two bits of aluminium joined with a "skeleton" hinge, bit cheap and floppy but does the job.

Nicked the idea from Dave D :)

Dave

post-21198-0-45890500-1419079926_thumb.j

Edited by Davey-T
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Just got this on the scope, been waiting for the Sun to go too low as it's on the Quark scope and didn't want to disturb it 'till now.

Only running on the AAF2 app ATM, need to remount the scope and see if I can get it to work with Maxim.

Dave

Very nice job. Love the mounting.

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