4 for $4

The other day I visited a thrift store and picked up some old electronic toys. One of these toys was a Kawasaki Electronic Drum Set. The drum set is about the size of a shoe box, has 4 different drum pads and only cost $4. I dismantled the drum set and found that there was a contact microphone glued to the backside of each of the drum pads. When the drum pads were impacted, the contact mics created a signal which triggered a sample of a drum sound. The signal sent by the contact microphones is actually the sound of the impact on the drum pad, however, this signal was used by the toy to trigger a pre made drum sound. The chip inside of the toy also stored samples of music which could be triggered by buttons on the surface of the toy. The tempo and volume of the music could be controlled by two fader switches. While tinkering with the toy, I found that I could also control the tempo of the music by licking my finger and pressing it to different areas of the chip. The tempo change was much more radical and unpredictable with this method. This method also caused the audio to suddenly cut out. Flipping the power switch off and then back on again fixed this problem, but had to be done every time the audio cut out. I decided to disconnect the contact microphones and drum pads in order to use them for a future project.