SnakeyJ

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.

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.

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.

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

Thanks Gina - reassurance much appreciated :-)

Gina - I've orded a couple of the 12v 28BYJ-48's (now currently on the slow boat from PRC), but wonder if you have varied the circuit diagram to give a direct supply to the motors. Dave's circuit diagram below: Shows the power supply to the motor as common with 9V supplied to the Arduino GND 29 and VIN 30. Will I fry the nano by putting 13.8V across this? Or have you modified the circuit to just supply the 13.8V to the ULN2003? There should be sufficient juice from my Startech hub to provide the 5V DC for the nano's logic.

They would all have different comm ports so should be okay. Though 3 cheap laptops might be a whole lot simpler and more stable [emoji3]

Dave - many thanks for providing the ascom driver and this great resource and tutorial. After finally borrowing a replacement soldering iron, I finally completed this last night and now have it working via Ascom with Firecapture. I still need to do another revision of the mount to fit my OO OC1 focuser and will probably upgrade to the 12V version of the 28BYJ48 to cope with the weight of the imaging train. I'll need to find a 4K7 resistor to complete the 1wire temp enhancement, but otherwise ready to roll when the clouds part