I Made a Calculator From Scratch
Now you don't have to think so hard to do a tricky calculation (under 20).
For this project, I used 2N3904 NPN BJT Transistors and 2.2k resistors. The circuit ran at 5V and drew about 100 mA of current. I'm planning to continue working towards a 4-bit computer, though I'm ditching the 7-segment display after this, at least for now.
Check out Ben Eater and Global Science Network! Their videos made this one possible.
@BenEater
@GlobalScienceNetwork