Description
A singular RCA adder of one of many designs. Includes inputs A and B, CIN, and COUT. CIN is the side input, COUT is the two-colored 4-long wire, and A and B are the levers at the back.
RCA adder designs are great for redstone beginners - they are simple to explain, build, and use.
However, there is a drawback: RCA has a delay for each adder you add. Each adder has to wait for the last to finish. That is where 'Ripple Carry Adder' gets it's name. It ripples.
This means that not every calculation will take the same amount of time, and thus RCA is not recommended for applications with sensitive timings. If you do plan to use it in something with a clock, like a CPU, probably ensure that the clock is slow, as to give the RCA time. And for pipelined CPUs? Forget it.
Related Schematics

256 color display
The hardware for the 256 colors resource pack, by zPippo

Jumbo Airplane
An airplane loosely modeled after a Boeing 747 or other wide-body airliner. Perfect for airport or city related project.

Cerebrum-0.4 -- CPU
Cerebrum-0.4, PICOlo_1109's CPUISA: https://docs.google.com/spreadsheets/d/1y0ApeDLECaKg-eRCr1qtvhsx0OteVB7QY5UVcZzkjQQ/edit?gid=0#gid=0NOT FINISHED