3D Printed Astrophotography Computer

control side on telescope

With the recent two month long stretch of clouds and rain, I decided to tackle the number one issue causing me to not take advantage of the rare (lately) clear sky…setup time. Living in the suburbs of Houston with a tiny yard, I don’t have the option of building a permanent, back-yard observatory. My best location is right in the middle of my driveway and even then I only have about 70 degrees of visible sky east to west…but I do have a clear shot of Polaris. The problem was that setting up is an hour long, very physical process and I can’t leave my gear in the driveway all night so I have to tear down at 2-3 in the morning…so…I would talk myself out of it most nights. If I wanted to image more frequently, I needed to simplify my setup/teardown routine!

Step one was easy and the most important. Getting a heavy duty medium size wheeley bar from JMI allowed me to leave the scope setup and just roll it in and out each night. This alone saved 45 minutes of labor!

Telescope

After using this setup for a while, I realized that I was still spending 15 minutes running cables to the computer and power to all the electronics so I started looking at on-telescope computer control systems. I did find two commercial options. The AstroBar was light weight and reasonably priced but feature and performance poor. The Eagle2 had the performance and many of the features I wanted but it was fairly heavy and very expensive. Having electrical experience, a couple of 3D printers, and plenty of cloudy nights, I began experimenting with stick PCs. The results were generally positive but I did run into a few issues. First, I found most of the sticks I tested to be fairly underwhelming from a performance standpoint. Running Windows 10, camera control, image capture, guiding software, etc. on 2 GB of RAM with an Atom processor proved troublesome at times. Plus, there were multiple occasions where I lost my remote desktop session to the stick and I had to drag a monitor, keyboard, and mouse out to the scope to plug in the stick and see what what going on. The first time this happened, I was at the Houston Astronomical Society dark site with no peripherals…3 hour round trip plus setup/tear-down time for no images. Very frustrating! Additionally, at this point, the cable monster was beginning to get a bit out of hand! The telescope looked like it had lost a fight with a drunk Radio Shack sales associate!

It was time to plan my ideal, custom Astrophotography, on-telescope computer/control setup.

Requirements:

  • Incorporate the following products into one system
    • Computer
    • Dew Control
    • Camera Control
    • USB Hub and Power
    • 12v Accessory Power
  • Provide at least 6 USB 3.0 ports (primary camera data, guide camera, PoleMaster, mount control, hand controller if doing PEC, focuser, one extra)
  • Power status monitor
  • Small integrated touch screen display (back up to lost remote sessions)
  • Single cable running off scope (power)
  • Small
  • LIGHT WEIGHT

After two months of prototyping and testing I am very pleased with the finial product…I call it The Cube 🙂

Specs:

  • Weight – 982g/2.16 lbs (this is actually 74g less on-scope than my previous non-integrated setup)
  • Size – 16cm/6.25 inch cube
  •  Intel M5 CPU, 4GB of RAM, 256GB of storage
  • 4 channel variable dew control w/low voltage cutoff
  • 7 external USB 3.0 ports each delivering up to 2.4 amps
  • 3 internal powered USB 3.0 ports
  • 5 inch multi-touch LCD display
  • Real-time voltage/amperage monitor
  • Highly regulated power control for the compute stick
  • QHY 10 camera control (TEC cooling/power/status)
  • Switched control for USB Hub, PC, Dew Control, and QHY CCD Camera
  • 4 unswitched 12v 5.5×2.1 mm accessory power jacks

Design and construction

I began the process by taking all the separate components I was trying to integrate and attaching them to a wooden block that could mount on the telescope so I could prove the concept and get a feel for the wiring involved and any potential pitfalls.

Prototype

Next, I 3D printed some components that would let me mock up the internal spacing requirements. The USB hub I decided to use based on size and weight was wedge shaped. I had to measure the angle and print a test wedge (orange component below) to stand the hub vertical for the mockup. The yellow stand below straddles the power distribution block and the buck converter used to supply the correct voltage (5v) to the USB hub. The red box houses the compute stick power regulator (more on that below) and the green shelf mocks up the location of the compute stick complete with opening for the cooling fan.

The next step was to layout the front and rear panels. The front panel contains the USB hub, individual power switches (hub, PC, dew control, and QHY10 camera), PC power regulator control, master power meter, and dew heater outputs. The rear panel contains the touch screen and dew heater controls.

As a starting point I found a great parametric box and panel maker script that allowed me to use OpenSCAD to define my panel layouts mathematically after careful measurements with an accurate set of digital calipers.

Screen Shot 2017-12-26 at 11.06.25 AM

This method let me rapidly print and test prototypes for fit and layout.

Time for the real design work. Using the prototype prints from OpenSCAD as a starting point, I used SketchUp Pro 2018 to design the final box and panels. The front and rear panels feature raised lettering which allowed me to change filament colors once that layer was reached during printing (I went with light grey panels, orange lettering, and a black box to match my Celestron RASA/CGX-L setup). The upper box has an inset detail with precise holes for the QHY DC-201 status LEDs (more on that below). The lower box has a built-in wedge to lock in the USB hub in the correct position as well as built in tabs for positioning and holding the power distribution block and buck converter. Additionally, the compute stick shelf and integrated latch has a dovetail which joins it to the lower box half.

Printing time!

Final parts ready for assembly.

One of the trickiest aspects of the build was powering the Intel STK2MV64CC Compute Stick. When I tested earlier Atom based compute sticks, all I had to do was wire up a mini USB plug to a 5V power supply and the stick fired right up. However, I wanted a stick with a full m5 CPU and 4Gb of RAM which meant going with the USB-C powered version. The first thing I did measure the input voltage and current with a USB-C multimeter.

Compute Stick Power 20

Thinking I was in good shape with 5V, I tried a simple 12V to 5V USB-C converter.

Compute Stick Power 12

The stick would power-up, enter the BIOS check screen, then shut down…odd.

So I tried a higher end buck converter…same result…power-up, BIOS check, shut down.

Compute Stick Power 14

So, I decided to take apart the AC power adapter that came with the stick to see how it worked. This unique adaptor plugs into the wall and then delivers 5V over USB-C. Additionally, the wall adapter itself has two additional USB 3.0 ports that act as a hub over the type C connection. (the stick only has one 3.0 port on-board).

Compute Stick Power 2

Inside, I found a normal 110V AC to 5V DC convertor attached to a daughter board containing the USB 3.0 ports and USB-C connection.

Measuring the output signal on the USB-C link, I found a non-standard signal embedded in the normal data channel. It seems that Intel decided to stop users from using any power supply except the supplied Intel version. If the BIOS does not detect this input signal on the data channel of the USB-C connection, it shuts down. There is no way around it. I guess they were tired of users burning up their compute sticks with crappy cell phone chargers or other poorly controlled power supplies. My options at this point were to run a LONG USB-C cable along with the 12V power cable down from the scope to the ground and use the Intel power supply…or…get creative!

I realized that the daughter board was the only component that mattered and it was very small and light weight. The bulk of the power supply was the 110V to 5v converter which I didn’t need. I already had an extremely accurate voltage regulator in the Cube which I was planning on using to supply 5V directly to the USB-C port on the compute stick. Now I simply needed to supply that same 5V to the daughter board and use it to supply the connection the compute stick. So, I desoldered the daughter board from the rest of the power supply, tested the voltage (it was outputting 5.14v – 5.22v to the daughter board), soldered on some new leads, and printed a very small box to house the card internally. At a cost of only 32g, I was able to power the stick internally and I gained two additional powered USB 3.0 ports inside the box which proved very helpful later in the design process.

The next bit of major circuit reworking dealt with the dew controller. I decided to use the excellent 4-channel dew heater control unit from Thousand Oaks Optical . But, obviously, I didn’t want the plastic housing or much else from the retail unit. I just wanted the control board.

To save weight and allow the board to sit as close as possible to the screen on the rear panel, I desoldered and removed the 4 output RCA jacks and the 12v lead and aux 12v RCA input. I also removed the primary choke and soldered it back on the rear of the board to lower the profile.

Next, I soldered new RCA output leads and 12v input leads directly to the back of the board and provided strain relief with hot glue.

One final bit of major electrical work before assembly. The QHY DC-201 has 5 status LEDs that provide information on voltage, TEC cooling, and camera fan.

QHY 8

I wanted to mount the DC-201 inside the Cube but I didn’t want to lose visibility to these status LEDs. So, I unscrewed the housing and removed the board. Using a straight edge, I carefully cut off the portion of the box with the status codes printed on it (I’ll use it later during assembly). Next, I VERY CAREFULLY desoldered the 5 LEDs being sure to label their position and polarity (LEDs are single direction electrical components). Using a very fine gauge solid strand wire, I re-soldered the LEDs to the board with 4″ long “extensions” protected in heat-shrink tubing.

Time to gather all the parts and clear the work bench for assembly!!!

First, front panel assembly.

Rear panel is next. The slots to the left and right of the screen allow me to attach a red overlay for imaging at a dark site with light policies.

The lower assembly begins by attaching the power distribution block and buck converter for the USB hub into their pre-printed spots on the lower box half.

Next, the USB hub is slipped into its custom fit wedge which features a lip to lock it in place. No glue or screws required.

Dropping the front panel in completes the front of the box.

Time to begin wiring all the switches, converter, regulator, and meter.

Wiring 4

Adding in the dew controller power (later put on an internal 2.1mm plug so the rear panel could be easily removed for servicing the Cube). Also wiring in the 12v supply for the switch’s LEDs.

Wiring 5

The Cube features 4 unswitched 12v aux jacks. These are a simple barrel connector soldered to leads and protected with heat-shrink tubing. I choose this particular connector because it came with a rubber cap to protect unused ports.

Adding in the aux jacks, the compute stick power supply, and internal USB 3.0 ports. Note the white USB-C cable to power the compute stick and the 3″ USB 3.0 cable connecting the hub to one of the internal USB 3.0 ports on the red power supply. The other 3.0 port is used for the touch screen (more below).

Wiring 6

The compute stick is attached to its custom printed shelf with a simple compression latch. The shelf is designed to place the stick in the center of the cube for maximum ventilation.

The compute stick is attached to the screen via HDMI (for video) and USB 3.0 to mini for power and touch. While the USB cord is moderately flexible, most HDMI cables are not. Additionally, the connections are on the side of the screen with only a few millimeters of clearance. Luckily, there is a company that makes flat ribbon cable in various lengths between 5mm and 80mm with every type of termination you can imagine. You simply order the tips and ribbon and snap them together. I used a 20mm straight USB 3.0 to right angle USB mini and a 10mm straight female HDMI to right angle HDMI.

Dew controller connected and the lower half is complete!

Wiring 9

The top half of the box contains the QHY DC-201 and the Losmandy dovetail adaptor.

First, the modified QHY DC-201 is attached to the roof of the top half of the box and the LEDs are inserted into their custom printed holes. The previously removed portion of the DC-201 is glued into an inset on the outside of the top of the box.

Next a custom 3D printed adaptor is attached to the top of the box to mate with a FarPoint dovetail clamp.

The QHY DC-201 is connected to the lower half power distribution with a 2.1mm plug and the two halves are screwed together.

bench cam side

Now, the only wire running off the telescope is a single 12v line. This can run from a battery or a well regulated power supply…I’m a big fan of BK Precision and use their model 1688B for my setup.

So far, this has really increased my imaging time. I can roll out of the garage, PoleMaster polar align, and be imaging in about 10 minutes. I can put the scope away in about 5 minutes. And I can run the whole setup from the comfort of my house with a remote desktop session to the compute stick.

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Backyard Sprinkler Park

Most of you know that I generally fill my summer up with construction projects around the house and for hire. This summer has been no different. I apologize for being absent from the blogosphere for a while, but I’ve just been enjoying my summer too much to sit and type. So far the for hire projects have included some sheetrock repair, hanging a new exterior door, fixing some rotten entry ways, enlarging some closets, new bathroom faucets, new kitchen plumbing, and a full bathroom remodel that had the room down to the studs and included new tile, shower, and walls. Pretty much every Friday through Monday I’ve been somewhere fixing something. It’s been great as I love doing this type of work, and it’s a nice way to supplement the teacher salary. On the home front it’s been all about the backyard. I’ll write about the pergola project in the next few days, but by far the most fun project of the summer is the sprinkler park. Being a stay at home dad (Tuesday through Thursday), this summer has been a blast, but unlike the previous years I now have a baby to take care of as well as an almost 4-year old. Needless to say this puts a damper on how much time I can spend playing with Annelise. As soon as we start something, Julianna needs her diaper changed or a bottle. Adding to this is the fact that the normal outlets for stay-at-home-moms are not available to a stay at home dad. She can’t have any of her girl friends over and we can’t go to any play dates. To make her summer a little bit more fun (and because I like cool projects) I told her we would build a sprinkler park right in our own back yard. So if you like totally pointless projects, or you just like the smell of PVC glue here is how to get started…

I didn’t really start with much of a plan. I had some ideas, but I really work best by going to Lowes or Home Depot and just playing with the stuff they have and seeing what I can come up with. I was in Home Depot with an assortment of 2″ PVC fittings stuck together in a configuration that should never occur in nature trying to spark some ideas when a man in a “Jon’s Plumbing” shirt looked over and said, “I don’t know what it is but it’s the most complicated thing I’ve ever seen.” The point is that there are a lot of things that can be used for other than their intended purpose…just be creative. I settled for lots of PVC, some small and large foam noodles, a sheet of pink high density foam house wrap, and lots of spray paint (the kind that is made for plastic).

Below you can see the basic core of each sprinkler. The basic idea is that water flows in on the left and can go into the sprinkler or out the other side to the next sprinkler. The whole point is that the sprinklers are all chained together and can be used separately or all together. The only issue with the design when this picture was made is that a second sprinkler hooked up to the right hand output side won’t have water pressure unless this sprinkler is on. My final design placed a T-fitting before the valve and just capped off the output side. Now all the sprinklers have water pressure all the time regardless of which ones are actually on. The valve I choose is a brass ball valve meant for gas. It was the easiest to turn on and off for kids.

You want the water to flow up into the sprinkler not down into the support tube (and the ground) so before gluing the lower tube in place I put a 2″ knockout plug on the top of the pipe.

After gluing the lower pipe in place you can see that the knock out plug has blocked the lower leg of the assembly.

I also painted on a nice layer of silicone caulk to the top of the knock out plug.

The lower pre-assembly is the same for all the sprinklers. Below you can see a basic pre-assembly attached to the “Dueling Noodles” sprinkler body. The top small pipe is capped and does not carry water…It’s just there to support the duck (you’ll have to look at the pictures at the end)

If you are going to use a noodle to carry water it must be one of the large noodles. The smaller ones just split under pressure. To attach a noodle to the PVC core you need an 8″ length of ½” PVC. I taped off ¾” at the end to protect it and coated the other end with plumber’s goop (actual name) and just pushed it into the noodle and let it dry for a few days.

Once it’s dry you can pull off the tape and attach any fitting you need.

If water is not supposed to come out of the other side you can glue a PVC plug to the ½” pipe. I used this technique on the “Tunnel” (again…see the pictures at the end)

For the “Dueling Noodles” station, I wanted to use small diameter noodles so I had to thread a length of ½” flexible hose through the noodle to bear the pressure.

For the “Flower Shower”, I bought the cheapest shower head I could find and broke it apart to remove the shower disc.

I filed the disc down until it would fit in a 2″ PVC compression ring fitting.

Then I screwed the fitting together to make the shower head. The flared out piece in the picture below (the one with the bar code) is not actually glued on anything. The 2″ PVC pipe carrying the water is passing right through it. The piece is a 2″ to 3″ adapter with the 2″ side cut off and just slipped over the pipe before the compression fitting was glued in place.

The flower head is just a piece of pink foam house wrap cut into a flower shape.

Using the basic ideas and techniques described above, I built the following four sprinklers.

Bucket Dump

This sprinkler, while being the most popular with the kids, is the most complicated to build as you must design a pivot mechanism for the bucket. I welded mine out of ½” square tubing and rolled a length of1/4″ round bar into a ring that the bucket could sit in. If you don’t have a welding machine (get one)…or you could probably create something out of wood. It may be a bit bulkier but it could be made to work. You can attach your pivot mechanism to the body of the sprinkler with 2″ pipe hangers. These are heavy clamps that fit around the pipe and have bolt holes for attaching your bucket contraption. I did a ton of math (finally a use for my otherwise useless Physics degree) to find the point on the bucket where the bottom of the bucket is heavier empty but the top is heaver at the moment the water reached the top, so it will dump automatically. Turns out the kids just want to dump it themselves, so I attached a string…

Dueling Noodles

This sprinkler is the most dangerous to the dry adults in the vicinity as it is capable of spraying close to 60 feet. The top decoration is just a silly duck noodle that I found at Wal-Mart and cut shorter and stuck on the top of the sprinkler body. The two noodles on the side can be picked up and sprayed at each other or any other moving targets within the neighborhood.

Flower Shower

This is the simplest and (according to Monique) the cutest sprinkler in the collection. We’ve even let Annie bathe out here. This is the sprinkler that first gave us the idea for putting little one ring pools at the bottom to protect the yard from turning into a mud pit.

The Tunnel

I couldn’t really come up with a cool name for this one, but it’s one of my favorites. Its two large diameter noodles attached together (using a 12″ length of ½” PVC and the goop described above) and have holes poked along the length. I actually used some 1/8″ tubing in the holes to get the spray to aim better. The tubing is attached to the PVC base with a threaded connection, so you can take the noodle off for storage.

The only part I don’t have pictures of is the actual anchor into the ground. I just used a 4-foot piece of ½” galvanized iron pipe hammered 2 feet into the ground. Into the lower leg of the sprinklers, I screwed in a 1 ¾” PVC cap with a ½” hole bored into the center. This fitting slips nicely into the 2″ PVC, and a simple wood screw from the outside holds it in place. With one of these at the top and the bottom of the lower support leg, the sprinklers can be slipped over the galvanized pipe. This makes the sprinklers stable enough to be left out all summer but portable enough to be stored in the winter. Come by and let your kids play sometime…the park is always open!

Welcome Home Julianna Theresa Nilsson

-By Monique 

If you haven’t heard the news yet, our little Julianna was born on March 12 at 12:16pm. We (and the doctors as well) were shocked at how chubby she is. Based on my pregnancy size and the latest ultrasound, it was predicted that she would be in the 6 pound range. What a surprise when she weighed in at 7lb 14oz. We love those very kissable chubby cheeks. Julianna looks a lot like her sister did at this age, only with dark hair. She is a great little baby so far, and big sis Annelise has been a dream with the disruption to her normal routine. Annelise is completely in love with her little sister, and Julianna calms down and lights up whenever Annelise sings or talks to her. Thank you for your prayers – we can’t wait for you to meet her. Here are a few pictures to enjoy:

Only a few weeks left!!!

I really can’t believe how quickly the time has flown by this go around. Just today I was looking at a calendar and it really started to sink in just how little time is left. I’m both excited and a little nervous at the same time. I guess that’s always true with change but I really don’t know what to expect this time around. I think the Astro’s lineup looks strong but with the soft pitching rotation I’m not sure. Either way March 31st is just around the corner. I love opening day…what did you think I was talking about? Seriously, I can’t wait for Julianna to arrive on March 12th. I know Monique is ready to have her insides back to normal and I’m ready for all the late nights taking care of the baby (with the Astros on the office Tivo of course).

Back to the Astros…Everyone has reported to spring training but our young superstar, Hunter Pence, is home recovering from lacerations on his right hand and knee. Guess how he got these injuries…He ran through a sliding glass door that he thought was open! I love it…at least the injuries aren’t serious. My favorite part of the story –

Pence jumped into the shower to wash the broken glass off of him, but when he noticed he was excessively bleeding, he called his parents. They told him to call 911, and soon after, according to Pence, “firemen, emergency people and medics came to the house.”

He called home first…what a guy.

Babies and Baseball – March is going to be AWESOME!!!