SFH900-A Low-Cost Miniature Reflex Optical Sensor Appnote 26

Whether for an industrial plant or a hobbyists drilling machine, an electric drive will hardly be acceptable nowadays without speed control. Incremental bar patterns simply applied to rotating shafts can be detected by the new Siemens reflex optical sensor, the SFH 900. The information can be processed with a minimum of circuitry, whether for a high rate of black-to-white transitions or just single, slow transitions.