The OPB120 through OPB123 devices consist of an infrared emitting diode and a Photologic sensor (which is a monolithic integrated circuit that incorporates a linear amplifier and a Schmitt Trigger). The OPB120 series have an LED and Photologic sensor mounted on opposite sides of a 0.080" (2.03 mm) wide gap of an opaque housing. The OPB12_A series have a molded 0.040" (1.02 mm) wide apertures located over both the emitter and the Photologic sensor. The OPB12_B seriesseries have a molded 0.040" (1.016 mm) wide apertures located over the emitter and 0.010" (0.254 mm) over the Photologic sensor. All devices in this series have the added stability utilizing hysteresis built into the amplification circuitry. The electrical output can be specified as either buffered Totem-Pole (OPB 120A, OPB120B), buffered OpenCollector (OPB121A, OPB121B), Inverted Totem-Pole (OPB122A, OPB122B), or Inverted Open-Collector (OPB123A, OPB123B).