Twist a volume knob and you may be turning one of two devices that look nearly identical from the outside. The split between a potentiometer and a rotary encoder is one of the cleaner illustrations of analog versus digital position sensing. A potentiometer is fundamentally a variable resistor. A wiper slides across a resistive track, dividing it into two halves and forming a voltage divider. The output is a continuous analog voltage that maps directly to shaft angle. This makes it inherently absolute: power up the circuit and the voltage already tells you exactly where the shaft sits. The tradeoffs all follow from that sliding physical contact: • Rotation is bounded, typically around 270 degrees for a single turn • The wiper wears over time, eventually producing scratchy, noisy output • Resolution is limited only by the ADC reading it, but so is the noise floor A rotary encoder reports motion digitally. Incremental encoders output two square waves, channels A and B, held 90 degre...