PIR (Passive InfraRed) sensor
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Limited stock.       PIR    Passive InfraRed sensor    $39.00 

This sensor has been tested with NXT using the Lego NXT conversion cable (W770323).

The PIR sensor detects motion of people and animals..

The Passive InfraRed sensor (PIR) is a sensor for the Lego Mindstorms™  Robotic Invention System.  The PIR senses motion of a warm object, like a person or animal.  This is the same type of sensor used in motion activated lights, and in some burglar alarms.  The sensor detects changes in infrared light.  Infrared is like normal light, except you can not see it with you eye.  Infrared is also called Radiant Heat.  There will be no visible indication when the sensor is operating.

NOTE:  The infrared technology used in this sensor is different than TV remote control technology.  This sensor will not detect or interfere with other Techno-stuff sensors, or with the RCX infrared communications port.
 

Motion detector for Mindstorms   PIR front view

Motion detector on RCX  Burgler Alarm

With just the RCX, PIR sensor, and a simple program, you can build a burgler alarm that will detect a moving person at a range of up to 20 feet.


You program the detector just like the Lego light sensor.  Use the Light Sensor block in the Mindstorms program environment to cause program branches.  The PIR returns two different values depending on what it sees.  In the example below, the RCX will turn on a light and beep six times when it sees motion.

Icon program for infrared motion detector


Read an independent review of the PIR sensor by Dave Astolfo.


 

Specifications

        *  Two PIR sensors may be attached to a single Mindstorms sensor port. When both sensors detect motion, the Mindstorms value is 99.