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The T-Board keyboard. And my first PCB! (Designed with OsmondPCB.)

A unique Stylophone-type keyboard that I designed for my electronic musical adventures.

Project Log

For more photos, including my prototype device and the complete, soldered board, go to my mediafire page: https://www.mediafire.com/folder/q4ave4tjk87ns/Bagpipe_Project and look for The T-Board.pdf.

Some of you may know that I’ve been haunting this site for about a year and a half now, asking lots of questions as I’ve been trying to build something electronic that sounds like bagpipes. A difficult sound to replicate! And I began with the ability to read a schematic. And nothing more.

A bagpipe has what’s called a “chanter,” a pipe that’s played like a flute and produces an odd scale of 9 notes. Additionally, there are the “drones” which produce 2 buzzy, or perhaps slightly growling, background hums, an octave apart.

My first device has a little 9-pushbutton keyboard. But, then I decided I wanted to extend the playing range from Middle-C to A5, tune the keys to piano frequencies, and retain the drones. I changed my chanter circuit slightly (I’m not sure that it’s better) and added a foot pedal to turn the drones on and off. I also built a 2-layer keyboard with foil tape that’s played Stylophone-style with contact devices. The adventure is entirely chronicled in what’s now 4 PDFs and a few audio clips on my mediafire page (link above). The PDFs are extensive. They include information that I found useful along the way, bagpipe tuning info, song arrangements, dead ends I went down, mistakes I made (one very major one in the first iteration), build photos, build changes... If you’d like a short, totally canned “do this and you’ll have a cool musical instrument,” you should go elsewhere. I’m still playing with it. Still trying things. Still learning...

But, the keyboard has become very cool. It’s even notable, I think. I call it my T-board.

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!

As soon as I built my copper-foil tape on painted masonite prototype, I wanted a slick printed circuit board version and began trying to figure out how I might produce it—using an old iMac running OS 10.9.5.

I discovered OsmondPCB. Two versions of the software are downloadable for free, and one of them is compatible with my old system.

It took a while for me to get the hang of it. But, from the time I downloaded it to the time I finally was able to send my files confidently to PCBWay in China, was just a little over 3 weeks. (If that seems long, I was probably doing lots of other stuff at the same time. And had to ask more questions and research lots of things related to PCBs.)

If there’s a parts library in the program, I didn’t find it. I drew the array of holes across the top (for my series of tuning trim pots and fixed resistors) from scratch. I created one combo and then duplicated it 22 times. I used 2mm-round component pads and made my traces the same width. I made the holes in the pads for the fixed resistors .035” and the holes for the trim pot legs .040”. The corner mounting holes are .125”. I made the “vias” that go through the “T” pads and the sharp/flat pads .035” also, so that if something happened to any of the traces, I could easily run wires beneath the board, in the same way that I built my prototype. (Although, there’s an easy-to-use via tool that has a smaller default setting.) I drew the board outline on the top solder mask layer, as I saw that recommended on another fabricator’s site. OsmondPCB allows you to establish “Working Area” dimensions (your board dimensions), as well as a margin around that, for extra work space. I kept a very small margin in my document at the end, and drew a 2-point line (.028”) around the board extremities, corresponding to the board dimensions. I ordered a nickel-gold solder finish called ENIG applied over the large key pads, which increases durability and decreases oxidation. (For that, I needed a solder paste file.)

The holes sizes above are what I ended up with, but not what I started out with. Unfortunately, I changed the size of most of my holes at the last minute and re-did that whole array across the top of the board and accidentally left out one trace. The back legs of all the trim pots should connect together. There should be a trace running across the whole length of the top of the board, on the bottom side, with a couple of extra holes for places to solder the RCA cord to (or whatever connecting cord you want to use).

I designed the top array of holes to fit Bourns trim pots, 260P-1-103, 10K multi-turns, which I bought from Electronic Goldmine.

I was able to solder all the trim pots at an angle to the board, so that the screw end points slightly upward, so that I can get a screwdriver into the screws more easily.

The missing trace was easily solved with one long wire winding between the trim pot back legs and soldered to each one. Not catastrophic, but definitely a bummer.

I’ve made available a folder on my mediafire page, as well, containing the files that I sent to PCBWay, for anyone who’s trying to create their own PCB for the first time and would like to know what Gerber files look like, etc. (Gerber files are just text files.) But, OsmondPCB also outputs postscript files, so I put together a PDF with a couple of screen shots and the postscript images of my board layers (copper top, copper bottom, solder mask top, solder mask bottom, and silkscreen. One of the screenshots shows the master board layout as seen in OsmondPCB. The other screen shot shows the solder paste file as seen in an online Gerber viewer. I sent the Gerber files and the PDF to PCBWay, compressed all together in a ZIP file. The bottom copper layer in the files I’ve posted is corrected and the postscript image in the PDF is correct. I’ve also added a page with fixed resistor suggestions for tuning to the Middle-C to A5 scale. I’ve “shared this board (with corrected files) on PCBWay, too: https://www.pcbway.com/project/shareproject/T_Board_Keyboard_ba2cc10e.html

I’m still experimenting with contact devices.

And I want to create a more distinctive sound for my drones. Something noise boxy, I think. I’ve ordered some piezo elements and some cellphone-type vibrating motors from Electronic Goldmine…

One last thing about OsmondPCB: I found myself going back and forth from working in millimeters to working in inches (by changing the grid dimensions). I created the resistor array across the top, working in millimeters, and the large key pads, in inches. I found it very useful to do up a sheet for myself with a list of inch to millimeter conversion figures. Reminding myself, for instance that 1/16” = 1.5875mm and typical breadboard and component lead spacing is .1” or 2.54mm. The program works in “mils” (thousandths of an inch) and millimeters. Mils was too much for my math-impaired brain. That sounds really stupid now. But, it was easier to glance at my cheat sheet and enter millimeters for all my dimensions.

I have 3 or 4 extra T-boards that I’d be happy to sell. Email me at brookware(at)vtelwireless.com and put T-Board in the subject line, if you’re interested. And be patient. I don’t always remember to check that email every day. (I had to order a minimum of 5 boards from PCBWay. I might keep a second board. But, I definitely don’t need all five.)

BTW, someone warned me that one’s first PCBs hardly ever come out exactly right. Prototype your board and go over and over your design. I might’ve spotted that missing trace if I’d slept on it and looked it all over one last time.

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