PCB Touch Piano

A piano for your pocket? Sure!

Using a printer toner transfer, copper etching solution, and a Teensy 3.2 we make a tiny MIDI controller that responds to a simple touch of a finger.

You'll need some materials:

100mm X 70mm copper PCB
Teensy 3.2
Ferric Chloride
Design Software (I used Illustrator)
Arduino IDE
Soldering tools
Digital Audio Workstation (I used Ableton Live)

I am more skilled in Illustrator than any PCB design software so I decided to give it a shot! It is unconventional but if you find any program do be a more natural way of designing circuits then by all means use that! a pixel width of 1 was sufficient enough for the circuit pathways.

Using your laser printer, load a sheet of magazine paper(I use a page out of MAKE:) taped to a regular sheet of paper a and send it though. Cut it out and get ready to prepare your Copper board.

Wash your copper board with steel wool and alcohol to make the surface ready to take the toner and to be sure it is free of any oils.

I splashed a bit of acetone onto the surface of the Copper and positioned the printout over it. once it was alligned correctly a added a bit more acetone on top of it and pressed down with a 2nd copper board(although you can use anything flat to do so).

I waited ~10 minutes and returned to wash the now dried magazine paper off under water. If the toner has transferred it should look like the last picture in the set. Now it is ready for the etching solution!

Use a safe container to pour the etching solution into. then let your board go for a swim. I was suprised that it took ~30 minute to dissolve the copper. Your mileage my vary due to temperature so check it often.

After it is finished rinse it off and use some steel wool to rub away the toner.

I soldered some headers on the outside pins of the Teensy and did some tricky soldering with the pins underneath to make it connect to all of the TouchSense inputs but after it was done it felt very secure to the board.

I'll attach the .ino file here, too. For this you'll need the Arduino IDE, Teensyduino, and set the board to "Serial+MIDI".

Once you upload you can check the connections!

Test out your connections, and celebrate if everything works like you had imagined it! If something is wonky check your soldering and code. I use Ableton Live for my sound libraries but it should work with Garage Band or any other DAW that you fancy.

Enjoy!