author
9Instructables172,426Views164CommentsSt. LouisJoined April 30th, 2016
Projects in light, music, and electronics. Find them all on my site: www.jbumstead.com

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100+CommentsEarned a bronze medal
10K+ViewsEarned a bronze medal
Arduino Contest 2016
Contest WinnerGrand Prize in theArduino Contest 2016
LED Contest 2017
Contest WinnerFirst Prize in theLED Contest 2017
Epilog Challenge 9
Contest WinnerGrand Prize in theEpilog Challenge 9
Make it Glow Contest 2016
Contest WinnerSecond Prize in theMake it Glow Contest 2016
Microcontroller Contest 2017
Contest WinnerRunner Up in theMicrocontroller Contest 2017
Invention Challenge 2017
Contest WinnerSecond Prize in theInvention Challenge 2017
Photography Contest 2017
Contest WinnerThird Prize in thePhotography Contest 2017
Remix Contest 2016
Contest WinnerSecond Prize in theRemix Contest 2016
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  • Desktop CT and 3D Scanner With Arduino

    Thanks! Looks like I forgot to add STL files. Just added it to Step 4.

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  • Understanding Emitter-Followers: Using Transistors to Reduce Sag

    Thanks for your clear explanation on clipping. I have been reading Art of Electronics and got stuck on why clipping was worse on the negative rail. Now I understand thanks to your instructable!

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  • jbumstead commented onjbumstead'sinstructable 13 Note MIDI Laser Harp25 days ago
    13 Note MIDI Laser Harp

    Sorry for missing your question, now I've got it. I think that I just plugged my control signal to the positive control signal pin and left the negative pin disconnected. I'd start with that and then check the driver manual (if there is one out there) before grounding the negative pin. Even if your differential amp isn't working yet, you can test the galvo is responding to control signal by plugging in a positive dc signal (like 3V from the arduino) to the positive control pin. No troubles for the questions. Glad to help!

    Glad I can help! The driver board of the galvo is connected to the +/-15V power supply. The power supply remains the same to the board. Don't send your control signals to the power pins. A separate pin on the driver board is used for the control signal that is coming from the differential amplifier. The board then sends the appropriate signals to the galvanometer. The attached image shows a galvo driver board that is similar to the one I used. Excited to see what you create!

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  • jbumstead commented onlonesoulsurfer'sinstructable Fizzle Loop Synth - 555 Timer27 days ago
    Fizzle Loop Synth - 555 Timer

    Thanks for your reply. A nice idea with dimming the LED.

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  • jbumstead commented onjbumstead'sinstructable 13 Note MIDI Laser Harp27 days ago
    13 Note MIDI Laser Harp

    Hi Piotr, Thanks for your questions. It has been a long time since I did this project, so I some of the details are fuzzy. After looking through my documents, I think I can answer your questions. Although, I bet there is a more efficient way to do it.After the non-inverting amplifier (sorry about the mistake in the text), the control voltage for the galvo varies from 0 to 12.5V, because the gain is 2.5 and the output of the R2R DAC ranges from 0 to 5V. This amplifier could be power 15V/GND or +/-15V. The issue is that the control signal from the galvo must range from -10 to 10V for the full range of scan angles. To offset the signal, I used a differential amplifier powered with +/-15V. If the amplifier were powered 15V to GND, then the control signal could not be negative and you would ...

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    Hi Piotr, Thanks for your questions. It has been a long time since I did this project, so I some of the details are fuzzy. After looking through my documents, I think I can answer your questions. Although, I bet there is a more efficient way to do it.After the non-inverting amplifier (sorry about the mistake in the text), the control voltage for the galvo varies from 0 to 12.5V, because the gain is 2.5 and the output of the R2R DAC ranges from 0 to 5V. This amplifier could be power 15V/GND or +/-15V. The issue is that the control signal from the galvo must range from -10 to 10V for the full range of scan angles. To offset the signal, I used a differential amplifier powered with +/-15V. If the amplifier were powered 15V to GND, then the control signal could not be negative and you would be limited to half the scan range of the galvo.The non-inverting input to the differential amplifier was 7V, so the output would range from around 5.5 to -7V, not the full range of galvo but good enough for my harp. I'm not sure why I didn't set the non-inverting input to 6.25V so that the output would range from 6.25V to -6.25V. Doesn't matter in the end, because I could align the galvo, even if it wasn't oscillating about its center position at 0V. I think I used LM741 op amp for both the non-inverting and differential amps. https://www.amazon.com/gp/product/B00CSKFT6A/ref=o...For the power supply, I used the +/-15V supply that comes with the galvo. I didn't know about DC voltage converters at the time, so I used another 9V power supply for the Arduino.Hope this helps!

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  • jbumstead commented onlonesoulsurfer'sinstructable Fizzle Loop Synth - 555 Timer5 weeks ago
    Fizzle Loop Synth - 555 Timer

    Cool 555 project. Very useful because I haven’t tried using them before. excellent find on the case! Looks perfect for your project. How does the LED blink rate and potentiometer affect the sound differently? Are they both changing the pitch? What is the frequency range of your device? Thanks!

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  • Desktop CT and 3D Scanner With Arduino

    Yes, a different camera will work. Michalis made his optical CT scanner with a webcam. See the comments below. Best of luck with the build!

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  • jbumstead commented onrzinurov'sinstructable Volca Synth Foldable Case7 weeks ago
    Volca Synth Foldable Case

    Thanks for sharing this beautiful piece. The cardboard prototype really helps show your entire design process.

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  • Desktop CT and 3D Scanner With Arduino

    Thanks for checking it out, Matlek!

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  • jbumstead's entryDesktop CT and 3D Scanner With Arduino is a winner in the Epilog Challenge 9 contest7 weeks ago
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  • Desktop CT and 3D Scanner With Arduino

    Thanks!

    Thanks for checking it out! RaviG28 suggested using a Pi too. You could display the images in real time and even do the processing automatically on the Pi right after scanning.Using sound is definitely feasible. There is a technique called Photoacoustic Tomography that uses light to excite the sample and detects ultrasonic waves emitted. You could also set up ultrasonic sensors and do 3D scanning, similar to what Super Make Something does with IR sensors: https://www.youtube.com/watch?v=-qeD2__yK4c

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  • jbumstead's entryDesktop CT and 3D Scanner With Arduino is a finalist in the Epilog Challenge 9 contest8 weeks ago
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  • jbumstead's instructable Desktop CT and 3D Scanner With Arduino's weekly stats:2 months ago
    • Desktop CT and 3D Scanner With Arduino
      43,683 views
      413 favorites
      50 comments
  • Desktop CT and 3D Scanner With Arduino

    Hi Michalis,I will have to try the linear polarizers and ImageJ for making the 3D reconstructions. I have already updated my matlab code to make sure the axis of rotation is directly in the center of the image.Excellent work keeping costs below 100euro. The dSLR will definitely help with resolution, easy triggering, and adjustable exposure. Right now I downsample the image so that it doesn't take so long for the reconstructions. The amount I downsample depends on how much I crop the image (e.g. how big the object is) and how long I want to wait.Lots of sugar is good. Maybe this is why Jaswant suggested soaking in saturated sugar solution.

    The distance shouldn't matter when using a telecentric lens. However, there may be some weird magnification issues when imaging too closely to the object. Here is a link for some advice on imaging small objects with photogrammetry: https://www.reddit.com/r/photogrammetry/comments/4n03js/tips_on_small_objects/Good idea with image from multiple heights to get better coverage of the object.Best of luck with the project!

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  • Desktop CT and 3D Scanner With Arduino

    Thanks for the vote!

    Hi Michalis,Thank you for sharing your optical CT scanner project and all of your documentation. And congratulations on winning those competitions too! This is a perfect project to get students interested in imaging.Your implementation, write-up, and results are terrific. I especially love your idea to use two polarizers to ensure that only light scattered in the specimen makes it to the camera. I guess that my results worked out okay because the rays of light from the source saturated the sensor if they did not travel through the sample. You also initially had some issues with scattered light in the box, which implies that using black out paper on the walls is really crucial for these homebuilt optical CT machines.I am also happy to see that this setup works using a webcam instead of a...

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    Hi Michalis,Thank you for sharing your optical CT scanner project and all of your documentation. And congratulations on winning those competitions too! This is a perfect project to get students interested in imaging.Your implementation, write-up, and results are terrific. I especially love your idea to use two polarizers to ensure that only light scattered in the specimen makes it to the camera. I guess that my results worked out okay because the rays of light from the source saturated the sensor if they did not travel through the sample. You also initially had some issues with scattered light in the box, which implies that using black out paper on the walls is really crucial for these homebuilt optical CT machines.I am also happy to see that this setup works using a webcam instead of a much more expensive dSLR. I downsample the images anyway for my reconstruction. Did you add any lenses in front of your webcam? If not, I wonder how big of a difference the telecentric lens that I used makes for the CT imaging.The last major thing that I might not have emphasized enough in this write-up was the importance of making sure that the axis of rotation is vertical and directly in the middle of the image. I actually just eyeballed the center of the images when cropping afterwards. I guess it was good enough for most scans, but I am now going to adjust my code to make sure that the axis is right in the middle of the image. Great results with the gummie bear reconstruction. I am impressed how clearly you can see the hole in the bottom where you mounted the sample. Thanks for voting!

    I was able to make 3D scans with the demo version, which is standard Photoscan. However, I couldn't export files, so I downloaded the free trial, which is the professional version. If you buy the standard version, you can of course export files too. For a beginner with this software, I couldn't tell much of a difference between standard and pro. I used Photoscan because I have a Mac, but there are other options. The free instructables class uses Recap Photo, but it requires windows so you will need to run parallels on your mac. You get it for free if you have a .edu email account. I would have used Recap Photo, if there was a Mac version. Mi_Tasol also suggested trying a program called Irfanview, but I haven't tried it yet. https://www.irfanview.com/

    The samples are sitting in sugar solution. We'll see how it works!

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  • Desktop CT and 3D Scanner With Arduino

    Thanks for sharing Irfanview with me, especially with my free trial of Photoscan ending soon. I think there are ways to automate the cropping in Photoscan by uploading a background image, but I haven't perfected it yet.You have a great idea for building a photogrammetry scanner that takes photos from multiple elevations. There is another great instructable that I found in the middle of my project on building a similar scanner by using a microwave as a light box: http://instructables.com.mevn.net/id/The-Microwave-A-C...For improving cropping, he uses what is called an "infinity wall." There is a stage for moving the camera up and down, but ultimately he just moves the camera up and down manually and uses the burst feature on his camera to rapidly take photos. One thing I have learn...

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    Thanks for sharing Irfanview with me, especially with my free trial of Photoscan ending soon. I think there are ways to automate the cropping in Photoscan by uploading a background image, but I haven't perfected it yet.You have a great idea for building a photogrammetry scanner that takes photos from multiple elevations. There is another great instructable that I found in the middle of my project on building a similar scanner by using a microwave as a light box: http://instructables.com.mevn.net/id/The-Microwave-A-C...For improving cropping, he uses what is called an "infinity wall." There is a stage for moving the camera up and down, but ultimately he just moves the camera up and down manually and uses the burst feature on his camera to rapidly take photos. One thing I have learned after completing this project is that you can keep the design for a photogrammetry system simple and still get amazing results. The turntable is the key component for making the scanning easier.

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  • Desktop CT and 3D Scanner With Arduino

    Thanks for sharing these excellent resources. The images acquired in both of them are beautiful too. Because I am just thinking about how to clear samples, the comparison done in the Kurihara paper is particularly helpful. Looking forward to figuring out how to make these solutions.

    Hi Udon, Thanks for your comment! Optical CT definitely opens manypossibilities for 3D imaging, and it can help you get a much betterunderstanding of how it is applied to human imaging. The case is closed on tonertransfer: great technique for many types of projects.

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  • Desktop CT and 3D Scanner With Arduino

    I forgot to include the cost of filament and the hardware, so it is probably closer to $150.

    Great idea to use a Raspberry Pi for this. You could display the images in real time and even do the processing automatically on the Pi right after scanning. I just added the matlab code to step 12. It is only around 200 lines. Matlab has an inverse Radon transform with filtered backprojection function, so I didn't have to write that part from scratch.

    You are probably right about the camera rig. I was worried about how heavy the camera lens was, and I have a history of overdoing it dowel rods! Thanks for your note.

    Thanks for your note! An MRI machine, now that would be a challenge.

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  • Desktop CT and 3D Scanner With Arduino

    Thanks Lance! I love that expression by the way.

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