Explanation: When you tap the black rubber circle by your finger the electric impuls is generated by the piezo transducer located under it. Signal is then carried to the "brain", which is an electrical circuit with a microprocessor (drum module). The brain transforms the signal to MIDI data and forwards them to the computer via USB or MIDI interface. In the computer MIDI data are played back using software drum synthesizer, such as BFD, Addictive drums, Toontrack...
The drum module I use is from Megadrum. Because I am not experienced in the field of electronics, I bought the kit from Synthex. Also the body is crafted by my brother. It is made of oak and spruce. For sensors are used rubber door stops purchased in store. Piezo transducers are freely placed beneath them and lies on the foam. Rubber is glued to the body. Foam supports are placed in the holes which are countersunk in the body (example).
I also made "hi hat pedal" (see pictures), so I can control the hi hat by my foot. Pedal works on the principle of optical resistor (from edrum.info).
Pictures and video:
input sensor
