The working Piezoelectric key.

Here is a diagram of a working piezoelectric key.


The design appears very simple because it is and it took a lot of thought to get it that way. Once you realize that a working keyboard needs at least 88 keys and to be fully Janko compliant it needs 264 keys, (the one I demonstrate on my first page has an intermediate 176 keys), you'll begin to realize the simplicity and economy are the name of the game.

If I count every wire in the design there are 7 parts to this key practically none of which need be machined or looked upon as 'moving parts'.

(Note: Some equipment such as an Oscilloscope and Volt/Ohm Meter  will make your life easier but are not actually needed for constructing a key, more on that later).

The list of parts are:
  1) 1 Piezoelectric strip, ($1.80 at windworld.com)
  2) 2 Mini dominoes, (28 for $2.00 at GameWorld on the Internet)
  3) 1 1.5 x .5 x .125 strip of "Headboard liner cloth purchased from any upholstery store.
  4) 1 bead of Hot Glue for making the beak at the end of the top tile.
  5) 1 Roll of sticky plastic film wrap, (Saran Wrap).
  6) Wire for attaching to the Piezoelectric film's leads.

Making a key.
    Step #1:  Solder a measured length of wire to each of the piezo films leads. (I found out too late that actually checking the polarity of the pulse and soldering the same color wire to the lead that actually produced the positive pulse would have been helpful bu not required.)

    Step #2: Wrap the piezo strip tightly in a small strip of plastic cling wrap. The piezo strip is destroyed by hot glue which tends to pull the conductive ink from the surface of the strip under force.
 
    Step #3: Wrap the cling film wrapped piezo strip in a strip of headboard liner cloth tightly to approximately 1/3 to 1/2 it's length.

   
Step #4: Placed the assembled sensor on the smooth surface of a mini domino and glue it into place. Pay attention to, if at all possible, assure that the leads at the back of the piezo strip are as flush as with the back of the domino due to the fact that they're metal and therefore prone to damage.

Step #5: Using your hot glue gun add a small bead of hot glue to the surface of the second domino approximately 1/8 inch from the leading edge. The tiny drop of glue serves as a 'beak' and transmit force to the outer edge of the piezo strip creating a more defined and sensitive response from the strip when struck.

Step #6: The final step is to glue the top and bottom halves of the key together creating your finished key. Alignment is Critical and you may want to spend some time developing various jigs to hold the pieces to together correctly as they're assembled. I found the clamp end of a 12'' crescent wrench to be most helpful.

And there you have it the finished key. In the next segment I begin to discuss the circuitry needed to make these keys sing. For those of you who are Engineers or savvy Hobbyist you need go no further to create your piezoelectric keyboard but if you are like me when I started, and don't know a diode from a hole in the ground the next discussions may be useful.