This sensor package is for line following Bot. Every now and then hobbyist who is willing to play with Line following Robot has a tough time with the IR sensor arrangement. This is a neat solution for them.
Calibration: To calibrate the sensors, you must tune the respective POTs.The left POT is connected to SEN1 and the right POT is connected to SEN2. Connect VCC and GND pins with the power supply and connect SEN1 and SEN2 pins with two LEDs.Keep tuning the POTs until the LEDs glow.
Now, Draw a Black line on white paper or vice versa. After the proper calibration is done, the LEDs will turn on when the sensors trace black and they will turn off when the Sensors trace white. That means the output is always either 1(High) or 0(Low).