If the paper moves away from the sensor, a green LED will light to indicate that the sensor output voltage has dropped to 1/3 Vcc or less. On the other hand, if the paper moves closer, a blue LED will light to indicate that Vout has risen to 2/3 Vcc or higher. This board allows the user to experiment with calibrating the sensor at various distances by monitoring the green and blue LEDs. Moving the sensor too far or too close to the paper, may prevent the circuit from calibrating. When this happens, a red LED indicator will flash multiple times and then remain lit to notify the user that the circuit could not calibrate.