Speed Sensor LM393

An infrared beam across a small slot, broken by the teeth of an encoder wheel. Each interruption produces a clean digital pulse, so counting pulses over time gives rotation speed and counting them cumulatively gives distance travelled. This is the standard way to add speed feedback to a robot's wheels or measure a fan or motor's RPM. Connect the output to an interrupt pin so no pulses are missed while the sketch is busy elsewhere. Clean digital pulses, ready for interrupt counting; Non-contact sensing with no mechanical wear; Standard slot width fits common encoder wheels; Onboard comparator gives a sharp square output