A clock with two D flip-flops.
Multisim design can be found here.
Video of the project in action can be found here.

As a part of building our knowledge on electronics, I independently created a breadboard circuitry of a 555 timer, which was the project objective. First, I designed a circuit using Multisim, and implemented it on a breadboard. In this project, I extended what I learned with the 4-bit counter project, and incorporated a clock to automate the cycling of the 4-bit counter. I learned the effect of the resistor and capacitor values in the clock period, and learned how to replace a manual process with a clock. In the world of automation, this was a critical skill to add to my digital electronics skill set.