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Switching to a compute stick - My approach

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#1 kraegar

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Posted 23 August 2016 - 08:43 AM

Last time I was out imaging, at the end of the night a USB port on my laptop died.  Really died.  This left me with a single USB 2.0 port, on an aging laptop.  I'd been planning a move to a solution like a compute stick but had wanted to wait for them to mature a bit more (and get 4gb of ram).  Since I didn't want to replace my laptop, I went with the compute stick now.  There's been plenty said about how they work, and I have nothing much to add there.  2gb of ram is enough for the polemaster, phd2, and SGP to run.  It plate solved fine and ran fine through the night, so not rehashing that.  What I wanted to post about was my solution to locating, connecting, and powering my compute stick.

 

I've had this in mind for a long time, but had wanted to do it after I got a new mount.  Since the extra money for that isn't materializing as fast as I'd hoped, I decided to just try it now anyway.  I decided to make a custom mount for my compute stick, so it could be attached to the top of my scope.  I have a 3d printer, and did all the design work myself in Fusion 360.  I followed entilza's excellent pick of the anker USB 3.0 4 port hubs to pair with it.  My design puts the hub and compute stick in one enclosure, with lots of venting (no vents on the CS are blocked) and access to all the ports.  I modeled a dovetail bar to go on top of my WO Star 71, and a retaining clip to hold the CS & Hub in place.  Here's the model of all 3 parts:

 

X7wX1Ud.png

 

I went through several iterations, this is the current one.  It uses a side set screw to lock in place on the dovetail.

 

Once I had that on my scope I considered being done, but I've always hated one thing very much: cables.  I had way too many cables, and some of them (I'm looking at you, SBIG) were way short.  I run on 110v power, and it was annoying seeing the power transformer box danging in the air.  Not to mention the cable snags and drags that would occasionally happen.  So, I decided to do something about it.  I thought about buying a 12v power distribution box, but why, when you can make one?  My design goals were easy: main power, switched, fused connections.  12v for my camera, 12v for my filter wheel, and 5v USB power for my compute stick & hub.  Easy enough.  I bought the bits, did some diagramming, more design, prototyping, and testing, and came up with this model:

 

sCHcQw5.png

 

It mounts on the same dovetail - the bottom prints in two pieces and is glued & screwed together.  The layout is organized to keep the internal wiring as short and clean as possible.  I used powerpole connectors, automotive blade fuses, and basic on/off switches.  The USB step-downs were purchased off of amazon, and the case was modeled around those.  I power it with a 12v bench power supply I already had.  The main cables running to it are 12 gauge "Wet Noodle" cable, which is super flexible, yet can handle the current just fine.  All connections from the bus bars are 16 gauge.  I reversed the orientation of the powerpoles for the input power compared to my camera and filterwheel to prevent mis-connecting things (though since the FW & camera stay connected, it's basically a non-issue).  They're all keyed, so connecting them backwards isn't possible.

 

Here's a shot of the inside of the power box all wired up:

 

O5kw1D7.jpg

 

And, finally, the fun pictures - here it is set up last night for the first time.  Please excuse the picture quality, I got started later than I'd meant to and had to take these in twilight.

 

First pic: the scope on the mount.  All the cables, etc on the scope in these first two pics now stays there, in place.  I don't need to disconnect any of this post imaging session:

 

olLRpiX.jpg

 

xOm7KsP.jpg

 

And, fully cabled up.  There are 3 wires running from ground level up.  One for a second USB hub (it's got the polemaster, mount, and a USB powered router plugged into it), +12v and -12v.  That's it.  The cables have a tie off point on my scope cable guide, and on the bottom end of the spot for the polar scope on my mount (also a little 3d printed guide).  This gives a full range of motion, but the cable weight is barely on the scope at all. (I did forget to use the velcro tie off on the side of the power box for the 12v power lines.  It's basically there just for strain relief on the connectors)

 

PP7RR38.jpg

xOLaqfF.jpg

 

Next I plan to make a box to keep all the stuff in the duffel bag in, so it's nicely attached and organized, instead of having to be messed with and risk tangles, etc.  That'll be pretty easy.

 

I had a lot of firsts last night with getting PHD2 & SGP going on the compute stick.  I started "fresh" with both, so it took a while to get settled and imaging.  Once I did, I got 4 hours of images with very few issues.  I think I have a buggy USB cable on my filterwheel, it disconnected twice, and I'm unsure the driver is very happy with my QHY5L-IIM guide cam.  It did eventually decide to behave and guided well once I got the balance figured out for my target.  It will work much better on a beefier mount than the AVX, but it handled it OK.  The scope, with all the bits attached, weighs 10.2lbs.  I don't have an exact weight on the power box and compute stick, but the plastic and parts are all very light, it's a small fraction of that weight.  Power and cabling was a non-issue all night, things ran smoothly, and I'd call it a very successful night.

 

The one issue I had that isn't really resolved (other than the possibly bad USB cable on the FW / driver issue with the guide cam) is that bahtinov grabber didn't seem to work well at all.  I had to manually focus, and don't think I did all that great of a job at it.

 

I'd be happy to answer any questions.  I'm sure one will be a parts list for the power box, it's rather simple, so I'll post it soon.

 

Edit to point out that I now control everything wirelessly using RDP from my laptop.  I plan to work on some longer range wifi, so I can hit it from inside my friend's farm house when winter comes around!


Edited by kraegar, 23 August 2016 - 10:23 AM.

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#2 kraegar

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Posted 23 August 2016 - 08:56 AM

And, it gets its own post, because it's important.

 

Thank you entilza - without your write up of the compute stick review, and the detail you put into it, I probably wouldn't have tackled this project yet.



#3 entilza

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Posted 23 August 2016 - 09:11 AM

Nice job Tony!  Very creative.  Now I know where you've been :)  Nice to have all that room on top of the scope with an OAG...  Glad the post helped, I have had perfect success with the intel stick it's extremely reliable.  One thing just to make sure, try running "RealTemp" on your stick to see the temperature of the device while it's in the box just to make sure it's not too hot, let me know the temps after running for an hour.



#4 kraegar

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Posted 23 August 2016 - 09:11 AM

BOM for the Power Box:

 

6 x http://www.digikey.c...ords=A112200-ND @ $0.50

6 x http://www.digikey.c...ords=A102007-ND @ $0.63

12 x http://www.digikey.c...eywords=1744041 @ $0.33

1 x http://www.digikey.c...ywords=S760K-ND @ $4.01   (Connector for my camera)

2 x http://www.digikey.c...1520-ND/5774323 @ 1.95

2 x https://www.amazon.c...e?ie=UTF8&psc=1 @ $6.99

1 x https://www.amazon.c...e?ie=UTF8&psc=1 @ $4.67

 

Misc: Blade Fuses, Spade connectors, 16 gauge wire, 12 gauge wire.

 

Edit to note the box did come out a lot taller / wider than I'd originally planned.  I'd like to find a better / more compact USB step down converter, and get some slimmer switches.  Though I really like these switches, they're stiff and not likely to be tripped by accident.  The fuses don't need holders because they're modelled into the 3d print, and use space connectors to attach.  There's roughly $4 in spade connectors used, I think.  (I had a bunch already, as well as the fuses & wire)


Edited by kraegar, 23 August 2016 - 09:16 AM.


#5 kraegar

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Posted 23 August 2016 - 09:13 AM

Nice job Tony!  Very creative.  Now I know where you've been :)  Nice to have all that room on top of the scope with an OAG...  Glad the post helped, I have had perfect success with the intel stick it's extremely reliable.  One thing just to make sure, try running "RealTemp" on your stick to see the temperature of the device while it's in the box just to make sure it's not too hot, let me know the temps after running for an hour.

 

Checking the temp is a good plan.  I checked it "by hand" last night, and it was fine.  But it was also a nice, cool night.  I'll get a monitor running on it so I don't have any surprises.  I was very careful to not block any of the vents, but there's still limited air-flow for sure.



#6 kraegar

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Posted 23 August 2016 - 03:38 PM

I really should get rid of the finder.  I don't use it now that I plate solve & use the polemaster, and it's kind of in the way now.



#7 pdfermat

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Posted 23 August 2016 - 06:36 PM

Thanks for posting this - I'm planning on doing something similar (someday)!

#8 kraegar

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Posted 23 August 2016 - 06:38 PM

Total weight of the compute stick, dovetail, power box and cables is 600g.



#9 Goofi

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Posted 23 August 2016 - 08:00 PM

Great write-up Tony ... and what a fantastic looking mount!   ;)



#10 gparamore

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Posted 24 August 2016 - 01:32 PM

Great to see the AVX loaded up with some hardware "automation"!



#11 kraegar

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Posted 24 August 2016 - 04:13 PM

The AVX wouldn't be my first choice at this point, but it's what I have, so I'll live with it.

 

Goofi - like that shiny polar scope cap I got?  I stripped the plastic one trying to find a way to add a ring for cable management, so I ordered an orange aluminum one from ADM :)



#12 FiremanDan

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Posted 24 August 2016 - 04:22 PM

Nice work. After I get over all my other speed bumps, putting everything on my OTA's via a small PC or PC stick is high on my list of to-do's! 



#13 tolgagumus

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Posted 24 August 2016 - 05:47 PM

I just found out this thing. It looks very interesting.

 

http://www.lattepanda.com/

 

I want to get one to try


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#14 kraegar

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Posted 25 August 2016 - 09:03 AM

I just had someone else bring those up to me - looks interesting.  I'd want to see some reviews first, but is likely a good option.  If I went that route, I could really slim down the compute stick case I have quite a bit.  (That's part of why I went with a printed dovetail, makes it all modular)


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#15 rgsalinger

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Posted 25 August 2016 - 09:39 AM

That's a great power distribution box. My next project is something like that - but I don't have a 3D printer so it won't be nearly as elegant. I've been using stick computers for about 5 months now. Right now I run cigarette lighter cables to a multi outlet and then just one wire down to the power supply on my Atlas. I'm going to rip all that out and use a Rigrunner solution which arrived just yesterday. I only wish I was as handy as you are!

 

I really can't work out why you need two more cables than I do. I can guess that one goes to a second hub. I don't have that issue because I use a 7 Port Startech (4 years old now) hub that allows me to connect the Polemaster, my auto focus system,  plus two cameras, a filter wheel, the mount. That accounts for the second cable. What is the third cable for? 

 

I find that the stick works but I long for a more powerful solution. Right now I can see the lag in terms of starting things up, plate solves, etc. When an image is downloading (I use MaximDL for camera control) I am locked out for 5-10 seconds which never happens on even my 6 year old laptop. Maybe next year we'll see another generation of these. I've switched over to using Remote Desktop from TeamViewer for two reasons. It gives me the ability to use two screens and has slightly better response time.  

 

Again, impressive work!

 

Rgrds-Ross



#16 kraegar

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Posted 25 August 2016 - 11:25 AM

Coming "down" from the top of the scope are 12v+ 12v-, and a USB cable.  That's it.  You could count it as two cables, if you used a 12v power that was +/- in a pair.  I didn't (hard to find in 12 gauge... which is overkill, but I like overkill rather than regrets or having to redo things).  The USB cable is for the second hub.  I have the polemaster, AVX, and a router plugged into it.  (The router is for wifi between the compute stick and my laptop, it was a cheap / easy solution).  I could run the polemaster & AVX cables up, there are enough ports, and power the router off the power strip, but that's one more cable going "up" then.

 

My other thought has been to just disconnect the polemaster after I'm done setting up, since i never adjust later on... but as soon as I do that, I'll accidentally bump my mount and wish I hadn't!



#17 kraegar

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Posted 25 August 2016 - 11:26 AM

Oh, and in the 3d design, I made it easy to add more powerpole connector spaces & fuses, so if I ever want to add a spot for powering a dew heater, or a auto-focuser, I can just print a new box up and transfer the parts over, and add in the new connectors.



#18 rgsalinger

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Posted 25 August 2016 - 11:44 AM

Ah. I didn't realize the +- wires were being counted as separate. I don't see the point of the second hub at all. I get that you need a router but the stick will attach itself to the router wirelessly. The Polemaster can be run off the powered hub so there's no cable dangling there either. There must be something about the AVX that I don't understand. I just run the mount USB off the hub attached to the top of the scope. I just got my WO71 back from getting an autofocus system added so I can't post a picture right now.

 

Anyway, this is a terrific setup. Someday all mounts will come with power and usb distribution as an optional feature. I bet they could sell a lot of them that way to the imaging community.

 

Rgrds-Ross



#19 kraegar

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Posted 25 August 2016 - 11:50 AM

The cable for the polemaster is awkward - sure I could run it up to the top of the scope, but cabling it was weird.  The AVX connection is a Serial cable off the bottom of the hand control, which goes to a USB cable.  Regardless of what I do, I would have to run that cable up.  There's no way to do this (in my config) without 12v + at least one USB going "up".  Rather than do that, it made more sense to add the second up, just have the data cable for that, and then I can connect whatever I want there.


Edited by kraegar, 25 August 2016 - 11:51 AM.


#20 kraegar

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Posted 05 September 2016 - 05:13 PM

An update after 3 nights in the field in a row:

 

I had some driver issues with my EFW2, reverting to an older driver sorted that, and now the compute stick is working flawlessly.

 

I swapped out my duffel bag for a plastic tote.  I used heavy duty velcro and attached all the things in the tote, and pre-wired everything.  Now I can just run the cables when I get there.

 

My arrival to power on time is now about 15 minutes.  10 minutes to do the polemaster routine.  Wait for it to get fully dark, calibrate PHD, and start imaging.  Teardown takes about 5 minutes.

 

Everything is working very well at this point, really couldn't be happier with my electronics setup now.  Once I sorted the EFW2 driver, I had no technical issues at all.  Collected 14 hours of images in 3 nights.

 

Arrival at my darker site to power on:

 

Run the extension cord

setup & level my tripod.

Setup the mount

Attach scope

Bring out tote.

Run cables for: Power, USB, Mount, Polemaster, Hand Control.

Power on.

 

Here's a look at the inside of the tote: http://imgur.com/Ottvc68


Edited by kraegar, 05 September 2016 - 05:22 PM.

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#21 entilza

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Posted 05 September 2016 - 05:35 PM

Cheater you got AC power :)  Nice Job Tony..  Having it refined makes it easier doesn't it.. I love having the stick up there too it's really smoothed things out for me.. It needs to be with the cold weather coming I don't want to be fiddling with things that I don't need to.

 

Pretty much the only thing that concerns me is not having a way to remote focus, I am debating a motorized focuser but I'm more interested in perhaps an optical upgrade in the future :)

 

Looks like you didn't need to upgrade the mount either which is great why re-invest if it's not necessary, plus the EQ6 is a lot more mount to lug around..

 

mp



#22 josh smith

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Posted 05 September 2016 - 06:14 PM

Thanks for sharing! Awesome stuff and I'm moving to the computer stick myself this week so nice to see others with some success.

#23 FiremanDan

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Posted 05 September 2016 - 06:55 PM

Which computer stick is the safe bet? 

There are a lot of options and I have horrible luck. 



#24 cdavid

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Posted 05 September 2016 - 07:01 PM

Nice job. Love the sweet little box.

I've been worried about my little stick as the winter approaches.

Considering a project box to enclose my stick with some dew pads to generate a little heat and keep things dry.

Dan...I've been using the second generation Intel pic stick. Works beautifully running SKYX pro PHD2 and Ascom for my setup

There are a few other options out there as well including mini computers.
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#25 kraegar

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Posted 05 September 2016 - 08:18 PM

Cheater you got AC power :)  Nice Job Tony..  Having it refined makes it easier doesn't it.. I love having the stick up there too it's really smoothed things out for me.. It needs to be with the cold weather coming I don't want to be fiddling with things that I don't need to.

 

Pretty much the only thing that concerns me is not having a way to remote focus, I am debating a motorized focuser but I'm more interested in perhaps an optical upgrade in the future :)

 

Looks like you didn't need to upgrade the mount either which is great why re-invest if it's not necessary, plus the EQ6 is a lot more mount to lug around..

 

mp

 

The AC power is great. I image at a friend's farm, and plug into the back barn.

 

As for remote focus, I'm currently debating the idea of building my own belt driven remote focuser using an arduino and a stepper motor.  It would require adding another channel of power to the 12v box, but that's easily done.  On the fence about the idea of doing that.

 

As for the mount... I really want to upgrade. The money just isn't there, so I'm working with what I have for now.  It'll work, sometimes I just have to kick it a bit to get it there.




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