I’ve been trying to build something that sounds like bagpipes. Hard sound to replicate! My first device has a 9-pushbutton keyboard, tuned to the bagpipe scale. But, then I wanted more notes, tuned to piano frequencies, along with the background drones. This is my second keyboard design. I designed the PCB in OsmondPCB, a version of which works on my old iMac, running OS 10.9.5. My musical adventures are chronicled in extensive PDFs and a few MP3s, available on my mediafire page. Go to https://www.mediafire.com/folder/q4ave4tjk87ns/Bagpipe_Project and look for The T-Board.pdf for more on the device above, in particular. (That PDF will tell you that I accidentally left a trace off of the board/files that I had fabricated. The Gerber files that have been uploaded here have been corrected. Layer2 has the trace that is missing from my board.)

The array of holes for components across the top of the board were sized for Bourns trim pots, 260P-1-103, 10K multi-turns (which I bought from Electronic Goldmine) along with fixed resistors. I.e., a series of 23 trim pot-resistor combos, one for each note. The fixed resistors get you in the ballpark of the tuning for each note, and the trim pot is for fine tuning. (I used 1/2-watt resistors. I think you could use 1/4-watts though.)

If you run a contact device over the stems of the Ts, you can play a series of adjacent notes in a tune. If you run a contact device over the tops of the Ts, you can easily play notes in a tune that are a whole step apart—C to E to G, for instance. Sharps and flats are available above and below, accessible wherever your ‘metalized’ fingers happen to be. The design works really well! My current contact devices are made from aluminum cigar tubes, which fit well on my index fingers. I’ve added a strip of hobby foam wrapped in copper foil tape to the ends of the tubes, to make the touch a little bit softer. But, I’m still continuing to experiment. I also want my drones to be more distinctive-sounding. Something noise-boxy, I think. I’ve got some piezo elements and cellphone-type vibrating motors on order...

The PDF that is attached here has 2 screen shots (one of the master file in OsmondPCB and one of the solder paste file, as seen in an online Gerber viewer; I needed a solder paste file because I ordered an ENIG finish applied across the large key pads, on my board). It also has postscript images of my Gerber files (Layer1, Layer2, Mask1, Mask2, & Silk1). The last page lists piano frequencies from Middle-C to A5 and the fixed resistors that I used for my tuning. If you use the T-Board with a different musical device or circuit, however, you may have to figure out a different tuning and a different set of resistors, I would think.

I hope someone finds this useful! Please give attribution to me as Jacki Brook.