This SHARP distance sensor bounces IR off objects to determine how far away they are. It returns an analog voltage that can be used to determine how close the nearest object is. These sensors are good for short-range detection.
Features:
Operating voltage: 4.5 V to 5.5 V
Average current consumption: 30 mA (typical)
Output signal: analog voltage
Output voltage differential over distance range: 1.9 V (typical)