Step 8: Solder white LEDs and current limiting resistors
Solder two 100ohm resistors to the protoboard. One resistor should be electrically connected to the header pin for arduino digital pin 2 and the other resistor to digital pin 3 (figure 2). Bend the leads of two white LEDs and solder to the copper side of the protoboard as shown in figures 3 and 4. Solder a (red) jumper wire between each of the 100ohm resistors and the anodes of each of the white LEDs (figures 5 and 6). Solder two (black) jumper wires between the cathodes of both LEDs and the to arduino ground (figure 7 and 8).