I’ve finally gotten jealous enough for the astrophotography subreddit to get back to work on this project. Jess bought me a Meade LX10 8″ diameter telescope several years ago for my birthday. I’ve used it quite a bit to view planets and try to take deep sky astrophotography pictures. This telescope isn’t one of those fancy ones you can type in whatever cool thing you want to see and it’ll drive itself to point right to it, that’s called a “GO TO”. Rather it has a simple “barn door” tracker motor. Basically, if you align to perfect true north, and set the wedge (the thing that mounts the telescope to the tripod) to your latitude, whatever you point the scope it will stay in view for hours in the eyepiece. If I know where to look, I can attach a camera to the scope and leave the shutter open and get some amazing pictures of nebulae and galaxies.
Being that I’m no good at polar alignment, I decided a few years ago to build an arduino interface that will connect my scope to my computer. The way this works is that I attach a webcam to the spotter scope (the small telescope that helps you find stuff) which looks at a particular star. The webcam pipe data into a program that sends signals out to the arduino to move the scope to keep the star in the same part of the webcam’s view. This way, I don’t have to be perfectly polar aligned, the software will help adjust the position of the scope for me.
I went on the hunt for a webcam that would work well with Windows and linux. This is because a lot of people are buying Raspberry Pi boards,connecting a webcam to them and attaching the whole setup to the telescope. Right now I’m testing on a windows machine so I need a webcam that’ll play well with both. I looked up the Linux Universal video Class (UVC) drive list to find a good modern camera. This list shows a good number of webcam models and brands that are known to work natively in recent linux distros.
The camera I landed on is the Logitec HD Webcam C270. It is a very cheap 720p 3 megapixel webcam. That’s overkill for the telescope, but it’s a good general use webcam and we can use it for video chats and such as well. This means my solution to attaching the camera to the scope can’t be permanent.
I keep a bunch of 3/4″ PVC pipes and connectors in the garage for prototyping, so I grabbed a 3/4-inch T connector. This connector can easily accommodate my 1″ outer diameter sighting scope.
The scope doesn’t fit perfectly, so I added some 2mm sticky-backed craft foam for a snug pressfit. (On a side note, I can’t tell you how useful it is having this kind of foam in the toolbox for all sorts of random purposes. I use it all the time) To accommodate the webcam, I used a hacksaw to cut a portion of the PCV connector off as shown. Then I wrapped a 3/8″ piece of foam on each of the cut edges of the PVC where it will touch the camera. This will help the camera seat well and stay in place when I attach it to the scope.
Finally, I used a smooth “ouchless” hair tie to hold the camera to the PVC tightly and aligned the camera with the hole in the PVC T-joint. Again, believe it or not, these hair ties are pretty useful for random jobs. In fact, I use a 8-inch smooth headband made of the same material to hold on my cheapo dew shield (more on this in another post.)
The final product is easy to use and quite robust. I think it’ll work quite well with my the rest of my setup. Since I’m still working that all out, I’ll post more as I learn more.
whole machine Forgive this messy rant….
After obsessing over CNC machines for about 10 years, and having some misadventures from time to time designing my own hardware and software, I jumped at the chance to order the original Shapeoko CNC mill mechanical kit as soon as it came out. It took me a year to find time to put it all together. After it was assembled, I connected up my old HobbyCNCPro Motor driver board to it. This driver board is for Unipolar motors, so I searched for some that would work. I found these NEMA 17s from pololu <>
On a previous attempt at making a CNC machine, I used Mach 3, but this time I went with LinuxCNC. The main reason I wanted the machine was to mill PCBs. The workflow was EaglecAD–>pcb-Gcode–>autoleveller–>linuxCNC.<> I made a few really horrible PCBs with the machine before realizing it simply wasn’t the tool for the job. The gantry had way too much play. The eShapeoko community was constantly updating and improving on the designs, so I waited it out until the V2 came out before the obsession hit me again when I saw how they doubled the gantry slides to improve strength.
After a year of V2 being on the market, I searched forums for a conversion pack but none was to be found. So I spent a while trying to define the differences between the machines. In the end, I spent probably just as much as buying a whole new mechanical kit, but here’s my process.
For a while now, I’ve been asking my students to submit their work as PDFs online using moodle (or email). I always use open source tools to annotate and grade these documents. There are several apps out there for this, I happen to use Xournal. The problem was that my preferences in Xournal were never saved. So I figured if I had the problem, maybe others do to. Here’s how to fix it:
First find where the preferences are stored. In Linux, these are found in a text file in my Home folder. I assume it will be similar in Windows. I edited this text file to automatically start with good grading tools already selected: ie. Red text with a Serif font.
$ gedit ~/.xournal/config
Then Ctrl+F and find “startup_tool” set this to “text”
Then Ctrl+F for “pen_color”and change this to “red”
Finally Ctrl+F for “default_font” and set this to “Serif”.
Save the file and you are done. Now every time you open Xournal, these settings will be loaded and you can just start commenting and grading without having to do any additional tool selections.
UPDATE: In Windows, Xournal configurations are hard to find. You must first set it up so you can view hidden folders and files (Go to Start menu–> Control panel –> Appearances and Optimizations –> Folder Options –> Show hidden files and Folders. Look for the radio buttons and select “Show hidden files, folders, or drives”. While I’m in here I usually also uncheck “Hide extensions of known filetypes” which lets me rename files including their filetype and see what types of files they are directly.
Once you do this, you can run Xournal and “Save Preferences” once as Ken mentioned in the comments below. Close Xournal first, then go to the path “C:Users\<username>\.xournal (Notice the dot in “.xournal”!!!) Open the “Config” file in a text editor (like notepad or notepad++ or Sublime text editor) Now you can make the changes above, and save.
A note of caution, edit a PDF with text, export it, then open it in another PDF reader to make sure it does not mess up. Sometimes when editing the config file, the Font doesn’t work correctly and I end up with garbage text and random characters on my exported copy which isn’t useful for students. If this happens to you, simply delete the config file and start over.
I got tired of going to the dropbox website to find the public link for files I put in the Public folder. On Windows you can simply right click–>get Public link, but I’m running LinuxMint with Dropbox version 2.0.22 which doesn’t support this (among many other things like Pausing a sync…)
Anyway I wrote a script that you can just drag your files onto and it’ll pop up a box showing you the public link. In Linux, a script alone can’t do this, but a script and a .desktop file can call a script to do it. Here’s what I got:
Save the following in a text file called “getPublicLink.sh” inside your Dropbox/Public folder. Make sure it has permission to run (right-click the file–> properties –>permission and check the box to allow it to run)
Today as I got into my car I realized that someone had broken into it and ransacked my glovebox and center console. I couldn’t nail down exactly when it happened but I couldn’t help but feel violated. Someone else in my neighborhood also had a break in. I decided to do something about it. I immediately went to the closest store and grabbed a cheap webcam and prepared to make a motion triggered surveillance system. (Man, I love Linux).
Many people are curious about linux, or maybe have even tried linux at some point. There is a huge difference between people trying linux, and people using linux. Hopefully this article will sort of ease your transition into using linux, either as a full time OS or even just enough to get around if you ever encounter it. Once you are familiar with software on one OS, its tough to move on but with this article I hope to list out some linux software that replaces many of the XP programs I once loved and how to run certain irreplaceable Windows software on linux.
(Image provided by Wikimedia Commons. Authors Larry Ewing, Simon Budig, Anja Gerwinski)
I have had some issues dealing with “experts” at local music stores and even reviews of products online; in particular dealing with USB condenser microphones used for music recording. I though that since I could see how so many people claim to be experts, yet give misleading information, I should do my part is dispelling some myths about USB audio hardware using a particular example.
Even some “experts” at the music store will have no clue what they are talking about, so let me enlighten you something so you won’t fall prey to their stupidity.
I like to record music from time to time on my computer. Nothing special, a riff here or there on the guitar, or a cover song or something. I wanted to have the simplest method for recording so when I chose to, I can focus on recording music instead of setting things up. I found the MXL USB.006 Condenser Microphone to be perfect for my application, however everyone and their brother advised me against it. Even the guy who sold it to me at “Guitar Place” said it wasn’t as good as running a standard condenser mic through a mixer and using a USB sound card. The one he recommended was the Behringer UCA202. So I bought them both to see the differences.