Fall Quarter Projects

Posted by magnetovore on November 4, 2012
Posted in: Blog, Instruments, Papercraft Computer. 1 comment

It’s been 6 weeks since I finished the version 7 Magnetic Cellos and #3 and #2 has been in the hands of my three cello friends  for a couple of weeks. They are testing out the instrument and, I hope, enjoying themselves as they learn a song or two. No major problems have surfaced, although I may have to add some extra magnets to the bow.

I’ve been keeping myself occupied while I give my magnetic cellists some time to learn the instrument. I’m learning about how to use imaginary numbers and Euler’s identity to solve circuits (Phasors are amazing) but I’m also using me free time to complete some nagging small projects.

Every inventor kid’s gotta have a nice pair of science tinker goggles. So my first project of this quarter was to make a nice custom pair of goggles. I cut out plastic circles  one orange filter and one tw0-way-mirror for each lens. The result is an awesome orange reflectivity. Halloween was an excuse to wear these goggles around campus.

Project number two is an evolution of the papercraft piano and cello scale calculators from last April (That’s a winder of a name… working on that). Folks on youtube and hackaday wanted a scale/chord slider made for the guitar, so, after a bit of canoidering, I was able to decode all the minor and major chords on the guitar, and fit it all on two business cards. By sliding one card past the other, any guitar chord can be displayed. An interactive and fun way for a novice guitarist to learn his or her chords, and it’ll fit in the card slot of your wallet.

Below is the latest prototype. I ordered 100 business cards with the chord pattern. I has to use an Exacto knife for the card in the picture, but once I get a hole puncher I’ll be able to make clean cuts and I’ll be able to pass around prototypes.

I’ve still got to test the actual thing with real guitarists, but when the thing’s ready, it won’t be too hard to print out a few on nice plastic cards, made of clear stock with transparent windows to show one card thought the other. There might be a market for sliding guitar chord guides (still working on a good name, do you have any suggestions?).

Finally, I’ve been working to improve the few mistakes I know I made on the Magnetic Cello V.7.0. I cleaned up the instrument’s printed circuit board, removing unneeded features and fixing the demux so that the bow jack can attach to the box without shorting out the power buses. Here’s the difference (improved board is on the right):

I think that’s it for now. You’ll be hearing more about the Magnetic Cello and Guitar Chord Slider once I get some good feedback. Hopefully I’ll get the thumbs up.

Done. Now What?

Posted by magnetovore on September 17, 2012
Posted in: Blog, Instruments. Leave a Comment

The three version 7 Magnetic Cellos are complete! It took a long week of sleep and video game deprivation, but I was able to finish the instrument before having to pack for college. Here is the picture I took at 5 in the morning, right after screwing the last neck in:

The instruments look and sound great. The coils look great and the construction feels solid.

But being an experimental run, there are of course a few tweaks that still need to be made. You may notice a few wires sticking out of cello’s box. As I discovered at 3 in the morning, the circuit does not sound when the two parts of the box are screwed together. Due to connectors on the aluminum box, one half of the box is tied to ground, while the other half is foolishly tied to plus 5 volts. When the two box halves are connected electrically, the circuit shorts out. It’s an easy fix, but it will require a fresh circuit board to fix the problem.

For now thought, the connector will be hanging outside the box. This quarter I’ll be doing some customer development and reliability testing by letting my cellist friends at the instrument. Probably around winter break, I’ll go back, adding or removing features from my friends’ feedback (business skills) and fixing and improving any technical problems that rise up (engineering skills).

So, by year end, I’ll have three new tried and tested version 7 Magnetic Cellos. No promises yet, but my old cello teacher is eyeing the instrument for his store, and I will look into selling an instrument or two on Amazon, Ebay, or an upgraded version of this website. I’ll be keeping cello #1 for myself, of course.

But for now, I’ve just moved back to college, and have class tomorrow. I intentionally left most of my tools at home; I need to focus on class and friends, and paying off some of that sleep and video game deficit.

A lot of hard work. But a pretty great summer.

Finishing Week

Posted by magnetovore on September 11, 2012
Posted in: Uncategorized. Leave a Comment

I’m ankle deep in sawdust and my goggles have fogged up in this strange un-southern-Californian humidity, but I’ve got just enough energy to let you know how things are going two thirds through the two week process of giving life to three new Magnetic Cellos.

Here is the list of text outlining what I still had to do as of my last blog post. I’ve crossed out what I’ve done:

I will be sourcing some wood and some music stands to be turned into endpins, using a jigsaw and router to cut out the wood using the laser-cut template, assembling and winding three coil, wiring and gluing three magnetic bows, drilling out holes in three aluminum boxes to mount knobs and switches and other sundry panel mounted electronics, soldering together these panel mounted electronics, staining the body and neck and coil, soldering together two circuit boards, applying the ribbon sensors to the neck of the instrument, screwing together the neck to the body, the coil to the box, and the box to the body, and, of course, burning or engraving version and serial number, the date, and my signature in a discrete part of the instrument.

At a glance, it looks like I’m half done. But working the wood took all of last week, and the box, bow, and coil are really all that’s left. And then I do the final assembly, tune and test. And play some Bach on each of the instruments.

Hopefully you’ve been following my twitter and getting  pictures every few hours this week showing my little bits of progress. But here’s some of the best stuff, below.

One cello body after being jigsaw cut and before being template router cut:

The template bit on the router is designed to stop along the template and cut the wood below:

The result is very smooth curves. Here are the three instruments after routing, edge rounding, and sanding. The necks and bodies are bolted together. The box is mounted, but not the coil yet:

I took a break from wood and finished all three circuit boards:

Then today went back and woodburned each instrument with its number, version, and name of creator. This information is burned underneath the circuit box and will only be visible during maintenance.

Finally, here are the three bodies after woodstaining. I still need to apply the protective glossy finishing layer. It’s finishing week!

Some Assembly Required

Posted by magnetovore on August 21, 2012
Posted in: Blog. Leave a Comment

My summer in San Luis is wrapping up, and the parts and tools needed to complete the next batch of Magnetic Cellos are either in the lab, the mail, or a nearby store. Lawrence and I have finished using the laser cutter on campus, and all that is left for me to do is… quite alot, actually. But before I explain what still needs to be done, here are some pictures of our progress:

Here is the newest coil. We tried to use acrylic glue to join the 4 acrylic layers of the coil housing, but because acrylic glue is toxic and hard to work with, we decided to use 6 screws to hold the housing together. These screws will be under the neck and out of view.

After finalizing and testing the design of the coil, Lawrence went out and cut out enough housings for three version 7.0 Magnetic Cellos:

And after a last minute decision to add 50% more magnets to the magnetic bow, we cut out and the final template for the neck and body of the instrument and three of each layers of the bow housing:

On the electronic front, my printed circuit boards came in the mail:

 

And I immediately populated the circuit board:

When I first used this circuit, I was getting terrible noise and tone problems. But after a few hours of frustrating troubleshooting, I found that I only needed to ground a few components mounted off the board, on the control panel. The circuit now works great, is easy to solder, and looks professional.

 

So we’ve got the electronics, the bow, and the coil ready for action, and a template to cut out the neck and body of the instrument. I’m going to be going home in a few days, to, among other things, eat some home-cooked meals and learn to drive. But I will also be sourcing some wood and some music stands to be turned into endpins, using a jigsaw and router to cut out the wood using the laser-cut template, assembling and winding three coil, wiring and gluing three magnetic bows, drilling out holes in three aluminum boxes to mount knobs and switches and other sundry panel mounted electronics, soldering together these panel mounted electronics, staining the body and neck and coil, soldering together two circuit boards, applying the ribbon sensors to the neck of the instrument, screwing together the neck to the body, the coil to the box, and the box to the body, and, of course, burning or engraving version and serial number, the date, and my signature in a discrete part of the instrument.

That was the longest sentence I’ve written in a few years (made longer by my unfortunate choice to use the gerund ‘-ing’ form of the verbs) and I won’t quiz you on what I just wrote. But the effect is there: I am going to be very busy in the next three weeks before school starts again. I’ve built half a dozen Magnetic Cellos before, though, and this latest version is designed to be relatively easy to build.

I’ll keep you posted on my progress. Don’t forget to follow me on twitter at @Magnetovore if you want updates (with pictures) of my progress.