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Concertina update/restart...
About 6 months or so ago I started work on an electronic concertina. In mid April, I put what I had in a bucket, hauled it off to Boston to demo to folks who'd appreciate it, and once I got home, I haven't looked at it since.

Recently, I've thought of continuing that project. To that end, I decided to look through my design schematics, board art, etc.

...and discovered that with OS upgrades and such, Eagle no longer runs on my system and all my schematics and board art are locked in files in a proprietary format I can't read.

I did find that there is a suite of open source electronic design software called gEDA, and started trying to reconstruct what I had done from the png versions of some of the schematics I have, as well as the general info I have floating in my brain. Some design changes were also in mind. But a lot was lost. For instance, I knew I had drastically simplified the design from the reference spec, but I had forgotten the details.

Today I had the bright idea of actually pulling the actual physical device from the the bucket it's been sitting in since April, and recording the circuit I actually used to connect this sucker.

Boy did I simplify the design... The reference MIDI design calls for 10 components (5 resistors, 2 capacitors, a switch, a diode, and an opto-coupler), the actual circuit I used had two, a resistor and a diode.

Now I have a good starting point to go back to the drawing board.