Reflective IR Proximity Sensor Module
This small circuit module can be used to detect obstacles and in general proximity with any object. There is an IR emitter diode which emits the IR rays and a Ir phototransistor receives the reflected IR rays. The amount of IR rays reflected from an object depends on it's proximity with the sensor. There is a potentiometer on this module which can be used to tune the proximity distance in various ambient lighting conditions.