8-Bit ADC Circuit
Built an 8-bit analogue-to-digital converter from scratch on a breadboard. No dev board, no library, just the ADC chip, some discrete logic, and a lot of jumper wire.
A potentiometer feeds the analog input. The converter samples it and outputs an 8-bit binary value across a row of LEDs, with a 7-segment display showing the same reading in decimal alongside it.
Partway through, the reading started jittering for no obvious reason. Turned out the fluorescent lights in the room were coupling noise into the circuit. Added a simple low-pass filter on the analog input and the jitter disappeared, a good reminder that the messiest bugs are sometimes just the room you're sitting in.