Sunday, October 26, 2014

Activities of the Week

The last week was very busy...

Bass Sticks
I was especially delighted to do some work in the Framingham Maker Space again!

Soldering New Boards
I soldered down most of the SMD components on a round of Music-Optimized Breakout Boards.

Mounting New Sensors
A few nights before that, I mounted the 4 new sensors that arrived for the bass stick (see Caught a Cold ).

Determining Optimum Resistor
Before making permanent mounting boards for the sensors, I needed to determine the optimum resistor to pair each one with.  I made a test jig for doing that and verified it work along with a Matlab script to plot and analyze the recorded signal and detect the resistance that produces the highest signal-to-noise ratio.  From what I've seen so far, it's between 35 and 40 dB.  Next step is to make this measurement official, buy some resistors and make a permanent board. 

Electric Eels

A Duet
Back at the MIT Maker Faire a few weeks ago I played an amazing duet with one of the organizers.  She was on fiddle and skillfully improvised a 2nd part to my lead on the classic hymn Silent Night.   By a nice bystander, it was recorded.  I was actually very shocked and surprised to play - caught off guard hearing a second note sounding after rehearsing it alone so many times - and what's more, the player's rhythm danced around the main line like a dancer whirling a beginner around on the floor.

By the second verse we played, we started to hit it off musically a little more and I was able to hear some of her stylistic expression and accompany them, pausing between phrases and accelerating the tempo in the middle of them.  I would love to do more like this:  This was the whole entire point of making these instruments - to play live electronic music along with others! 

A Tuning Correction
Also during that duet, the violinist showed me the tuning was slight incorrect for the Electric Eels - about 20 cents or 1/5 of a semitone. This surprised me since the math in the software had been carefully conceived accurate, but it was true nonetheless.

So I also spent a few minutes this evening, discovered the cause and fixed it.  This required digging out my old black MacBook to edit the software and upload it.  I made an attempt to start a repo on BitBucket with it, but the commands I tried didn't work.  That was probably because it appeared to have already been a git repo?!  I'm not sure how that happened, I'll have to look deeper into that.

Despite the confusion with the source control, it was very nostalgic to edit the old code again.  By the way: to fixi it was a simple matter of changing the number '90' to '89' in the initialization...

Speaker Grille

Also, if you remember back to last week, I made a new, wooden speaker grille for the Red Electric Eel at the Framingham Makerspace.  I sanded the edges of that grille to fit better inside the instrument this evening.  With the edges sanded, it fits nicely, a tight fit.  This will protect the speaker from unusual foreign substances I have discovered inside there, like popcorn, both stryofoam and the kind made from corn kernels.

I Broke a Wire!
During all of these Electric Eel operations, I managed to break a wire on the keyboard.  That took a few minutes to fix, but the news here is that the terminal on the keyboard switch itself had worn itself off!  I guess the light brass-like material gets brittle with vibration over time.   I'm not surprised, this keyboard didn't have sufficient strain relief like most of the others built after it.  At some point, I'll overhaul the whole thing, but it will hold for now, through the Christmas season.

Magnetic Field and Inductance
I also spent a lot of time reviewing material on fields and inductance. Each time I go back to this topic, I get a little more of an intuitive picture of how it all works.  I hope some day to understand it fully!  Or at least enough to make highly efficient generators, motors and speakers. 

Speaking of the Christmas seasons, today Tanya bought a set of 10 mini Christmas Carol books with lyrics and sheet music.  I'm delighted we'll go caroling with friends! 

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