Proximity sensor The Proximity sensor (part 9583) can detect objects very roughly up to 15 cm away, depending on the shape of the object and other properties (reflection, colour, etc.). The motion sensor is an active IR (infrared) sensor. One of the visible parts emits a light while the other is the detector. The LED light is pulsed at 7 kHz. The sensor can work with 5 to 9 volts.
We used this sensor in this video: