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

8 bit 5hz torchless divider
Pipelineable 5hz 8 bit divider

Tamed Wolf
From https://mc-blueprints.weebly.com/blueprints.html

Hex for-loop
Outputs once for every signal strength inputted. So if a signal strength of 7 is inputted, the output will flash 7 times.It has a few nice configuration options:- You can change the pulse duration of the output by increasing the delay on the locked repeater. Keep in mind that the delay on the repeater that locks it needs to be equal to the delay of the locked repeater.- You can also change the delay between pulses by increasing the pulse extenderI also made a version that is 2-wide instead of 3-wide but is one block longer and uses a redstone lamp. You can find that on my account page as well.