Step 1: Materials
(x1) Audio output transformer (radioshack #273-1380)
(x2) 1/8" mono jacks (radioshack #274-0251)
(x1) 3" x 2" x 1" project enclosure (radioshack #270-1801)
(x1) Piezo transducer (radioshack #273-0073)
(x1) 6' stripped-end audio mono cable (radioshack #42-2434)
(x1) Mini audio amplifier (radioshack #277-1008)
(x2) 6' audio mono cable (radioshack #42-2420)
(x1) Assorted shrink tube (radioshack #278-1627)
(x1) Audio player with output jack
(x1) Roll of double-sided tape
Step 2: Solder
Solder the green wire from the audio output transformer to the ground tab on the other mono jack, and the blue wire to the signal tab. This will be the output jack.
Trim the black wire to remove any exposed uninsulated wire.
Step 3: Holes
Drill both of these marks with a 1/4" drill bit.
Step 4: Install
Finally, mount them firmly in place with their mounting nuts.
Step 5: Glue (optional)
Step 6: Close
Step 7: Piezo Disc
Carefully break away pieces of the enclosure until you can fully free the disc. Be careful not to bend the fragile piezo disc, or it may not work.
Step 8: Solder
Slide a little bit of heat shrink tubing onto each of the leads.
Solder the ground lead to the mono cable's outer insulation wire.
Next, solder the red signal lead to the cable's inner insulated signal wire.
Cover the solder joints with heat shrink tubing, and briefly use a heat gun (or other heat source) to shrink it into place.
Step 9: Plug
Plug one end of a standard mono audio cale into the transformer enclosure's input jack.
Step 10: Amp
The external speaker jack should receive the mono cable already plugged into the audio input on the transformer enclosure.
Plug a new mono cable into the audio input jack on the amplifier.
Step 11: Audio
Step 12: Tape
Step 13: Stick the Piezo Onto Something
Don't forget to turn the amp on, and the volume up.