This sensor package is for line following Bot. Now and then hobbyists who are willing to play with Line following Robot face a tough time with the IR sensor arrangement. This is a neat solution for them.
TwoLTH-1550 reflective object sensors have been used here. The LM358 dual OPAMP works as a comparator with two reference voltages set by two POTs.The sensors have 0.5-inch spacing.
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) just as the word 'digital' indicates.