This info could be useful in other projects, so I put it in its own build page.
- Radio Shack 273-073 Piezo Element
- Mouse Pad
- Rigid plastic board (e.g., polyethylene -- I used some scraps, left over from my Proton Pack build, that originally were "For Sale" signs from Office Depot)
- small (about 1/4" diameter) foam rubber stick-on feet
- Silicon adhesive/sealer
- utility knife
- cutting board
- tin snips
- metal straightedge
Step 1: Cut Mouse Pad
Measure the size of the pads to your liking. I used the width of my ruler as a guide and made my pads square. Mark the lines in pencil on the mouse pad.
With the mouse pad on a hard cutting board, use the metal straightedge as a guide and cut the pad with a utility knife. Try to cut through the pad entirely in a single stroke.
Step 2: Cut the Plastic Squares
Cut plastic squares roughly the same size as the pads you cut in Step 1. They don't have to be exact -- in fact, a little smaller is preferred. I trimmed mine down using tin snips. Another useful technique here is to score the plastic along a straight line using a utility knife, then breaking the square off by bending along the score line.
Step 3: Crack Open the Piezo Element
The piezo element comes housed in a protective plastic case:
We need to set it free from its cold, plastic home. My preferred way to do this is to put it in a vise and squeeze the jaws until the lid pops off:
Be VERY CAREFUL! Wear safety goggles -- the lids sometimes fly across the room. One of these popped straight into my eye; fortunately I *was* wearing safety goggles.
Once you have the case open, gently remove the round piezo element within:
Be careful not to break the wires away from the element.
Step 4: Trim the Piezo Element to Size
Using tin snips, cut away most of the piezo element until just a small amount remains surrounding the soldered-on wires:
The smaller footprint of the modified element means less chance of your finger tapping the element directly. They seem to work better if they pick up vibration from a little distance away.
I assume they aren't as "hot" (don't generate as much voltage when tapped), which means less chance of picking up crosstalk from other nearby triggers.
Step 5: Assemble the "Sandwich"
Using silicon adhesive assemble the trigger in the following order (top to bottom):
- Foam pad
- Piezo Element
- Plastic Square
- Foam stick-on feet (3)
For the piezo element, try to keep it on a corner, away from the middle of the pad:
For the stick-on feet, try to keep them away from the piezo element. This minimizes vibration from other triggers reaching the element.
And that's it!