As a kid one of my favorite book series were Forrest Mims Circuit Scrapbooks. They were interesting to read and build the circuits out of. One of the projects that was in my opinion the most fun to play with is a binary guessing game from The Forrest Mims Circuit Scrapbook, Vol 1 page 121. Since prototype PCB prices have dropped recently due to competition in China this was a project that seemed interesting to convert to a PCB.

Schematic:

Changes to above schematic:

• A 10K pullup was added to the 74193 side of S1 to prevent noise from loading new numbers to guess.
• A .1 μF bypass cap was added to the 555 timer to prevent ringing in the output.
• The circuit is powered by a 9V battery. This battery goes to a switch. After the switch a LM2596 buck module is used to drop the voltage down to 5V

Gerbers:

https://github.com/mdunakin/PCB/tree/master/BinaryCompare

Photo of finished PCBA: