Arduino circuit/breadboard not working at higher voltage?

Yes, the last PDF I linked to was a 7805 regulator, with figure 1 showing 0.33uF on the input side of the regulator and some smaller value on the output side.

The C6, etc parts I referenced are from the arduino schematic I linked to also. Print that out, find the parts, and get them setup up on your protoboard the same way. If you're gonna play with electronics, you're gonna have to dive & start getting used to looking at schematics.