Engineers had learned that a resistor, which restricts the flow of electrical current, is best made of certain materials and a capacitor, which stores electrical charge, of others.
As it is made entirely out of circuit board, users can solder components directly to it -- such as a light dependent resistor or a microphone to make it respond to sound.
The modified N900 attaches a resistor that responds to a squeeze at four different pressure levels, and doles that out during a traditional or Skype-based call as a vibration on the other end.
On your breadboard connect the MIDI circuit as follows: The collector is connected to a 220 ohm resistor which is connected to the second pin from the left on the back of the female midi connector (labelled pin 5).