The module has on board potentiometer that lets user adjust detection range. The sensor has very good and stable response even in ambient light or in complete darkness. The sensor module can be interfaced with Arduino, Raspberry Pi or any microcontroller having IO voltage level of 3.3V to 5V. Applications Obstacle avoidance in robots Production counting on assembly lines Presence detection Security systems Features LM393 Comparator based detetction circuit is very stable and accurate On board potentiometer sets obstacle detection range On board Power LED indicator On board Obsatcle Detection LED indicator 3.0MM mounting hole for easy mounting the sensor. Male header for easy connection Good Accuracy: By use of Infra-red LED transmitter the module performs well in Ambient light Technical Specifications Model Number: FC-51 Detection angle: 35 ° Operating Voltage: 3.0V – 6.0V Detection range: 2cm – 30cm (Adjustable using potentiometer) size : 3.1 cm (L) x 1.4 cm (W) Overall Dimension: 4.5cm (L) x 1.4 cm (W), 0.7cm (H) Ative output level: Outputs Low logic level when obstacle is detected In-active output level: Outputs High logic level when obstacle is not detected Current Consumption: at 3.3V : ~23 mA at 5.0V: ~43 mA Pinouts VCC: 3.3V-5V power input pin GND: 0V power pin OUT: Digital Output Pin Documents and Download Infrared Obstacle Avoidance Proximity Sensors Module FC-51 product review video LM393 Comparator IC Datasheet A useful link on construction and working principle of obstacle avoidance sensor