Now that the note bottle assembly is built, it is time to build the electronics that will connect the servos to the Pi. This step is relatively simple, as all that you need to do is connect the Pi directly to the signal wire of the servos (usually yellow or white, sometimes orange) and provide power to the servos.
Since this project has the scope to use a lot of GPIO pins, we will use the Pi B+ for this project, which has an additional nine usable GPIO pins on its 40-pin header than on the older Pi model B's 26 pin header.
For reference, the circuit we will construct is laid out similar to the following diagram (note that for simplicity, only one servo is shown here):
The first step to create the electronic parts of this project is to ...