TT electronics OPTEK Technology enhances long distance reflective switch with adjustable sensitivity

“The OPB725A-18Z switch includes an externally-accessible trimpot, which allows customers to adjust the sensitivity of the device depending on their application-specific needs,” said Don Cook, product engineer for TT electronics OPTEK Technology. “The device is shipped with two M18 x 1mm plastic nuts to allow for easy mounting into an 18mm (+0.2/-0) hole. The switch is ideal for use in applications that require feedback on the presence or absence of an object, such as vending machines, mail sorters and conveyor belts.”

The OPB725A-18Z switch is tested to ensure detection of an 8” x 8” 90% diffuse reflective white card at a distance of 18”, with the sensitivity set to maximum (clockwise rotation) by the trimpot, which is accessible through a 4.3mm diameter hole in the sensor body.

Additional applications for the OPB725A-18Z long distance reflective switch include assembly line and machine automation, equipment security, machine safety, as well as door and end-of-travel sensing.

The OPB725A-18Z long distance reflective switch features an 850nm LED, and is offered with 48” (122cm) 26 AWG wires with mounting nuts. Power dissipation is 250mW, maximum collector voltage is 30V, and collector DC current is 50mA. Operating temperature ranges from 0°C to +50°C.

While an object is in the reflective path of the switch, light from the LED is reflected back to the housing, irradiating the surface of the logic output sensor. This causes the output NPN transistor to turn “on,” providing a “low” (0.8V max) output voltage when connected to the appropriate value pull-up resistor. When the infrared light from the LED is not reflected to the Photologic sensor, the output transistor turns “off,” minimizing the IC(ON) current and providing a “high” (22V min) output.