The IR sensor detects a reflective surface once per rotation. Arduino measures the time between detections, calculates RPM, and displays it on the LCD. If RPM exceeds 3000, the buzzer sounds an alert.

Photoelectric sensors detect objects and surface changes using variations in optical properties. Each sensor includes a light emitter and a receiver, with most relying on infrared light. In optical ...

The traditional theremin is more or less an audio oscillator with two metal rods. Using proximity sensing, one rod controls the pitch of the oscillator and the other controls the volume. [Teodor ...