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  #201  
Old 12-01-2014, 07:11 PM
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dtrewren (Dave)
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Morning all from a very chilly UK

Excellent Martin, glad everything is up and running. I picked up your first post early this morning ans was scratching my head trying to figure out what might be the problem but sounds like you have figure it out and got everything up and running. Still not sure why the dll didn't install correctly though. Sounds like a privileges thing - what operating system are you running and 32 or 64 bit ? It maybe you need to execute the driver install as administrator - Windows 7 is really pedantic about who can do what and when

The SharpSky Pro driver will not work in any shape or form with the original kit design. The respective driver authenticate the hardware to prevent any mix ups and generate an appropriate message saying connection not possible.

Cheers & clear skies,

Dave
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  #202  
Old 12-01-2014, 07:15 PM
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dtrewren (Dave)
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Hello Ian,

I have just had a look at the JMI EV focuser and it looks like it wouldn't be difficult to fit the motor. I have attached the focuser I think you have, is that correct ?

Cheers,

Dave
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  #203  
Old 12-01-2014, 07:26 PM
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mill (Martin)
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I did install the Ascom driver with admin privileges and it is a 32 bit machine.
I only got a dos box and not an install screen as usual.
On the computer i used to get the dll, i got the proper install screen and not the dos box, it is just weird

It will be clear the whole week as it looks like so it will be a nice test for the Sharpsky
Thanks again Brendan and Dave
Brendan i will bring the two motors tomorrow after work.

Cheers,
Martin.



Quote:
Originally Posted by dtrewren View Post
Morning all from a very chilly UK

Excellent Martin, glad everything is up and running. I picked up your first post early this morning ans was scratching my head trying to figure out what might be the problem but sounds like you have figure it out and got everything up and running. Still not sure why the dll didn't install correctly though. Sounds like a privileges thing - what operating system are you running and 32 or 64 bit ? It maybe you need to execute the driver install as administrator - Windows 7 is really pedantic about who can do what and when

The SharpSky Pro driver will not work in any shape or form with the original kit design. The respective driver authenticate the hardware to prevent any mix ups and generate an appropriate message saying connection not possible.

Cheers & clear skies,

Dave
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  #204  
Old 12-01-2014, 07:43 PM
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dtrewren (Dave)
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Hi Martin,

Very strange that is a first ......

If you ever get a moment maybe you can have another go and grab
a screen shot ?

Cheers,

Dave
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  #205  
Old 12-01-2014, 08:16 PM
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mill (Martin)
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I have to make it a video because it is a very fast dos box
Will do that tomorrow.

Martin.




Quote:
Originally Posted by dtrewren View Post
Hi Martin,

Very strange that is a first ......

If you ever get a moment maybe you can have another go and grab
a screen shot ?

Cheers,

Dave
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  #206  
Old 13-01-2014, 08:13 AM
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wasyoungonce (Brendan)
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Quote:
Originally Posted by mill View Post
.....Brendan i will bring the two motors tomorrow after work.

Cheers,
Martin.
Make mine strawberry! I like strawberry!
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  #207  
Old 13-01-2014, 11:17 PM
torsion (Bram)
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All very exciting. I have finished the distribution box and soldered up the various cables. Just working on a single 10-17 A power source ...

Brendan, I presumed that the 2.1mm power connector has the centre +12V, right? Just checking, believe it or not I have seen it the other way around. But if so, I can easily mod the cable.....

thanks,
Bram
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  #208  
Old 14-01-2014, 08:58 AM
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wasyoungonce (Brendan)
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Hi Bram

yes all power connectors are centre pin +ve...although you can bet sometimes someone will get it wrong or decide to swap them around in design!

I received the encoders today and will do some work on the system...it's a bit hot atm so I'll be trying to keep away from the soldering iron! Nearly all over..."bar the shouting!"

Interesting to see that Martins worked at my place fine but he experienced teething ASCOM issues on his set-up. I may be creating more headaches for Dave than he'd like!

Brendan
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  #209  
Old 14-01-2014, 04:51 PM
torsion (Bram)
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Quote:
Originally Posted by wasyoungonce View Post
...it's a bit hot atm so I'll be trying to keep away from the soldering iron! Nearly all over..."bar the shouting!"
No worries, there is no rush. Enjoy the heat I guess..
Thanks,
Bram
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  #210  
Old 14-01-2014, 05:16 PM
torsion (Bram)
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Hi Dave, I received the PIC controller this morning. Thank you.

Now I will see to find a stepper motor. Is there an optimum 'focus travel' per step? That is system dependent I would say. Far away from focus it would be linear (sort of the aperture angle of the cone per step). Rambling on a bit, sorry. Will see to read up on it.

Thanks heaps.
Cheers,
Bram (from boiling Canberra)
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  #211  
Old 15-01-2014, 07:01 AM
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dtrewren (Dave)
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Hi Bram et al,

Yes, there is a critical range for focus which is intimately dependent on your telescope optical speed, below is a table giving the critical depth of focus for scopes of various speeds.

So for example my Crayford on my solar scope was to hand and moves by 6mm with five turns of the 10:1 input control so ...

6000um / 5 = 1200um / revolution

SharpSky generates 2880 steps/revolution => 1200 / 2880 ~ 0.42um/step

The scope is about f/8 so that is 184 / 0.42 ~ 438 steps to cover the complete critical focus range of the scope - more than enough resolution to accurately nail focus.

Hope that's correct and makes sense ?

Clear skies,

Dave

Focal Ratio Depth of Focus
f/2 12 microns
f/3 26 microns
f/4 48 microns
f/5 72 microns
f/6 104 microns
f/7 141 microns
f/8 184 microns
f/9 233 microns
f/10 287 microns
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  #212  
Old 15-01-2014, 10:27 AM
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wasyoungonce (Brendan)
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Daves info is spot on but I'll add some. You can check out ccdcalc.exe to find how various scopes and CCD combo's go together and part of the info given is Critical Focus Zone (CFZ) per combo.

As Dave said shorter FL scope have smaller CFZ...so you want lots of steps from your focuser in this zone...not too many as it will be verrrrry slow! Longer FL scopes...not so critical.

You can calculate various stepper combos on your focuser by Circumference C=πD (lets use D=5mm, the pinion for the drawtube diameter, for arbitrary sake, then each revolution of the pinion = 15.7mm movement). If I choose a stepper that has 2040 steps per revolution (one I used, has internal gearing) then I get each 2040C=π5 ~ .007699mm (~7.7 micron per step, 15.7/2040).

In a scope that needs CFZ = 20 microns then this is not good I'll need a stepper with more steps per revolution either thru smaller step angle or bigger gearing...or even a smaller DT pinion.

If you connect via a 10:1 reduction pinion drive then obviously you will get 10 times more step accuracy per step "point 7 microns" per step (depends on the pinion). This is probably just acceptable for this small CFZ. Given lets talk an F7.5 scope as an average scope then it's CFZ is ~123 microns so 7 microns per step is fine.

Anyway hope this helps, try not to choose a stepper that has too many steps per revolution as movement is slow...but more accurate.... Have a look around this may help you decide on choosing. No one can tell you how many steps you need in the CFZ...the more the better but too many and the focus movement rate is very very slow!

hope this helps.
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  #213  
Old 16-01-2014, 02:13 PM
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wasyoungonce (Brendan)
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Ok all done, tested running just like a store brought one..or two ..or three! Martian has his already.

Peter4059 and Bram I'll need you post address and emails ..by PM so I can send them, probably Monday, I need to sort packing etc.

I tested them all with my stepper system, all functions: Temp measure and compensation; manual control and manual control change; USB connection and connect via ASCOM ok; check all functions via computer; and Runs my ML stepper just fine.

I also did current draw checks and these were the same as original, spot on. So I'm happy to release them into the wild.

So, I'll send the: PCBs; PCB LED looms; cases; manual control and temp probes (both already made up). You will need to cut and drill and file the case for the PCB to fit in...honestly I am time short atm so I'll leave that part to you both but I'll send vai email a drill/cut CAD drawing with measurements on this.

I'll include all hardware necessary to secure the PCBs but as said leave the case cutting to you both. I'll also send some small mounting notes and details.

Finally...done!
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  #214  
Old 16-01-2014, 02:51 PM
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mill (Martin)
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Also do not run any stepper with a current consumption over about 500/600mA.
The ULN chip is strong but will overheat and you will have to replace it (like me ).
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  #215  
Old 16-01-2014, 05:51 PM
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Thanks for doing all that Brendan. Soldering the small bits is quite a challenge. I'm off to Bunnings to get a stepped drill so I don't stuff up the box.

Have pm'd you the address.

Cheers,

Peter
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  #216  
Old 16-01-2014, 11:23 PM
torsion (Bram)
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Quote:
Originally Posted by dtrewren View Post
Yes, there is a critical range for focus which is intimately dependent on your telescope optical speed, below is a table giving the critical depth of focus for scopes of various speeds.
Thanks. Airy disks hey.


Quote:
Originally Posted by wasyoungonce View Post
Daves info is spot on but I'll add some. You can check out ccdcalc.exe to find how various scopes and CCD combo's go together and part of the info given is Critical Focus Zone (CFZ) per combo.

As Dave said shorter FL scope have smaller CFZ...so you want lots of steps from your focuser in this zone...not too many as it will be verrrrry slow! Longer FL scopes...not so critical.
I have a Celestron 9.25", so will need to work out the pitch of the focus screw (should not be to hard). But I would say a factor 10x of 20x less then the critical focus zone should provide plenty of resolution.

Thank you both, it does help.
cheers,
Bram
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  #217  
Old 16-01-2014, 11:25 PM
torsion (Bram)
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Hi Brendan, Thank you!! That is mighty great.

i sent you a pm as well.

cheers,
Bram
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  #218  
Old 19-01-2014, 04:34 PM
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jwoody (Jeremy)
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Hello all
Does anyone (or can you provide a link Dave) for the Ascom driver for the sharpsky kit focuser? I think the link on your website Dave is perhaps an old link for a old driver version (3.14)?
I have moved all my astro control software to a new pc.
Thanks
Jeremy

Last edited by jwoody; 19-01-2014 at 05:15 PM.
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  #219  
Old 20-01-2014, 12:00 PM
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wasyoungonce (Brendan)
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Hi Jeremy, not sure which version you are after, so:

The 1st version with PIC18F4550 is here.

The 2nd version, aka the shaprsky kit (PIC18F2550) is here.

Client software is here.

Brendan
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  #220  
Old 20-01-2014, 12:02 PM
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wasyoungonce (Brendan)
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Kits sent out this morning, should get them soon gents.

Sent Alistair a small package of SIL resistors and SIL connectors.

So, all done! Good luck gents.
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