hughgilhespie

Hi Peter,

My solution, which is based around the Lesvedome / VellemanVM110, is to have the main control box mounted on the static part of the observatory. I added an Arduino based controller to the Velleman system. The Velleman board responds to the Lesvedome ASCOM driver and rather than using the Velleman outputs to switch the  motor control relays on or off directly, the output signals are picked up by my homebrew Arduino board. This board then controls the motors. I actually use stepper motors but you could just as easily use the Arduino board to control relays to switch DC motors on/off. The big advantage of sending the motor control signals via an Arduino is that you can use fairly cheap wireless modules to send the signals to another battery powered Arduino / relay motor controller mounted on the rotating dome.

I realise this is a bit daunting if you are not comfortable with using Arduinos or similar but it does make for a fairly straightforward solution to automating the dome shutter. My system using stepper motors could be much simplified to become a relay driven system. In fact, thinking about it you could use the classic Lesvedome VM110 relay circuit for the dome rotation and all you would need to add for remote shutter control would be two ready made boards, Sparkfun Teensy 3.1 XBee adapters available from Cool Components in the UK, together with the Teensy 3.2 and XBee modules and probably a relay board. 

If this is of any interest please send me a PM and I will be happy to give you more details.

Regards, Hugh

If you are using Chinese Nano clones they don't like voltages much over 9 volts on Vin. You MAY be OK with 12 volts but it would definitely be better to add a regulator to your board. Something like will give you 8 volts and it only needs the regulator and a couple of small ceramic capacitors.

Regards, Hugh

44 minutes ago, skybadger said:

I also read that direct drive with inbuilt encoder can do 13M ticks per rotation but the spec says the positioning precision is 90" - what does this mean ?

Hi Mike,

A link would help.

Regards, Hugh

Hi Gina,

I bought a Pet Bed Heater to keep my obsy laptop a bit warmer. Someone on here suggested it - unfortunately I can't remember who - but it does seem to do the trick. They are about 20 watts, so don't actually get very hot but they are waterproof, so OK-ish in the obsy. I would still be a bit careful though and only run via an ELCB supply.

Regards, Hugh

Hi Mark,

Probably teaching Granny, but perhaps posting on Cloudy Nights might be more likely to get a response? They seem to have some very knowledgeable people posting. As you said, it will be interesting to track down what is happening.

Regards, Hugh

Gina,

It's a con - pure and simple!

Do a search on Beelink software repairs.

Regards, Hugh

Gina,

Have alook at this site. It may help.

http://www.howtogeek.com/175649/what-you-need-to-know-about-using-uefi-instead-of-the-bios/

Regards, Hugh

6 minutes ago, Gina said:

Ah - is it...  I have a gert big reel of CAT5 but could buy CAT6 if it's faster and would make a difference.  Thanks Hugh

Just a thought - if you have the crimper and a couple of sockets and plugs then why don't you make up a 'dummy' Cat 5 15 meter cable and try it. See what speed you get without all the grunt work of digging trenches, etc. It would only take an hour or so to make the cable..................

Regards, Hugh

I'm not an expert but if you already have Cat 5, it PROBABLY won't make much difference over 15 meters or so. I think the speed measurements are based on a total length of 100 meters, of which 90 meters is the solid cored cable with 2 by 5 meter stranded, flexible bits at the ends.

There is also Cat 6A now - another chance to spend yet more money................

Regards, Hugh

24 minutes ago, Gina said:

I see.  Thank you Chris

Since I shall be digging up the grass between house and observatory, I could lay CAT5E cable in MDPE water pipe in the ground under the weed membrane and gravel.  What bit rate do you think I could get out of that?  It would be about 15m long.

Hi Gina,

I suggest you install Cat 6 rather than Cat 5. It's about the same price and faster!

Regards, Hugh

A heartfelt 'Thank You' to Herr Otto Diesel!!

Hi Choo Choo,

Just for interest, I have uploaded some pics to my gallery showing my dome driver motor. There is also a short video of it in action.

Regards, Hugh

Hi Choo Choo,

I am happy to help in any way I can so please feel free to contact me.

Regards, Hugh

Hi Choo Choo,

I have recently travelled the same route you are proposing. My observatory is a Pulsar 2.2 metre, the more modern design which has an exposed internal dome flange suitable for attaching a timing belt. I went with a 25 mm wide T10 timing belt glued in place with CT1 adhesive. You need to be a bit careful to make sure that the tooth pitch is close to 10 mm across the bit where the ends of the belt meet but this isn't too difficult.

I didn't bother with measuring the torque needed as several others have used this system successfully using motors rated at 2 Newton Metres or better. I chose a geared stepper with a holding torque before the gearbox of 1.89 Nm and a 4.25:1gear reduction. This gave a theoretical maximum torque of around 10 Nm, more than enough. 

The other Pulsar domes that I know of that use the timing belt system only use one drive motor and that's what I did. 

The motor itself drives through an 18 tooth pinion. To keep the pinion in contact with the timing belt, there is a spring loaded pinch wheel running on the reverse side of the flange. The whole motor assembly is fitted on a pivot arm that is securely attached to the dome wall. These mechanical complications are required to cope with the distinct lack of circularity and the variations in thickness of the dome flange. If you are making your own they may not be necessary.

My dome automation is a work in progress but I have got the basic motor rotation of the dome working so I can confirm that this design works well. For various reasons I chose to use a stepper motor rather than a basic DC motor. Obviously this adds some complexity but it offers a lot of benefits too in terms of more precise control and an easy way to detect potentially serious problems such as the dome jamming and the motor burning out - or worse!

Hope this is helpful.

Regards, Hugh

Hi Corpze, I would also like to hear about this. Ideally I would like an ASCOM driver that interfaces an Arduino Mega to the ASCOM Safety Monitor. I am happy to connect my cloud and rain sensors to the Arduino - as well as lots of other bits and pieces - but I have no idea how to get the safety status information shared with ASCOM. 

Regards, Hugh

Hi Hugh

I have uploaded the full schematic and full layout (still need the drv8825 sub-board) to the site under DRV8825 folder.

Yes, the Focuserv125_DRV8825_F.ino supports LCD/push buttons/probe etc

Cheers

Robert

Hi Robert,

Brilliant - many thanks.

I am looking forward to a very focused Christmas!!

Regards, Hugh

I have added an Arduino based DC motor controller unit that has same functionality as RigelSys nFocus or JMI MicroMotor HandPad or FCUSB device.

Its at http://sourceforge.net/projects/arduinofocuscontrollerpro/

in the files folder DC Focuser L9110S

Full schamatic, code, windows app, layout, parts list, ascom driver etc to be posted.

Cheers

Robert

Hi Robert,

Thanks for posting this, it looks to be just what I want and I have ordered a suitable Nano and the 5:1 NEMA17 motor and DRV8825 board. I intend to make the full version with 16 x 2 LCD and push buttons.

I have downloaded the files I think I need from Sourceforge but I am a bit confused about the details regarding the construction for the full version using the DRV8825 driver. Is there a schematic for this? I can't see one in the Sourceforge file lists?

Also the PDF 'myFOCUSERDRV8825.pdf' refers to the Arduino code being for a mimimal system but the sketch 'Focuserv125_DRV8825_F.ino' seems to have the code for all the bells and whistles, so is this the code I need to use?

Sorry if I'm being dim but I am relly keen to use your design, fits my requirements to a T.

Regards, Hugh