Providing design engineers with a reflective device capable of operating in dusty environments, Optek Technology has developed a long-distance infrared switch that exhibits a reflective distance of more than one inch. Designated as the OPB732 series, the reflective switch configuration includes an infrared LED and phototransistor and is enclosed in an opaque housing to reduce the sensor's ambient light sensitivity.

Whenever an object is in the path of the device, light from the LED will be reflected back to the housing, irradiating the surface of the phototransistor. Both the emitter and sensor are protected by a clear window that enables the device to operate successfully in dusty environments, such as those in industrial and automotive applications. The OPB732 reflective switch is, therefore, well suited for non-contact reflective object sensing circuits in equipment security, machine safety, assembly-line and machine automation, as well as door and end-of-travel sensing applications.

The OPB732 series light-emitting diode operates at a wavelength of 850 nm and dissipates 100 mW. The maximum forward current is 50 mA and the maximum forward voltage is 1.8V (I_f = 20 mA). The reverse dcvoltage is 3 V with a reverse current of 100 microamperes (V_r = 2.0V). Electrical performance of the output phototransistor is characterized at collector-emitter voltages of 30 V, collector dc current of 50 mA, and power dissipation of 100 mW. The OPB732 series assembly is offered with either PC board through-hole pins or 24-inch leads. The phototransistor can be configured as either a common-collector or a common-emitter device. OPTEK’s OPB732 reflective switch is priced at $2.97 each in quantities of 1000. If stock is not available, lead time is from eight to 10 weeks.