In this YouTube video, the team from Mythbusters try to beat a thermal intrusion security sensor (a passive infrared sensor, aka PIR, that detects thermal differences). See how ...

Electromechanical PIR-Sensor Interface IC Controls Any AC Load Oct. 8, 2008 The LS6506R is a pyroelectric infrared (PIR) sensor interface IC that is designed to drive a latching relay.

How it works: When something triggers the sensor, the Arduino records that moment as triggerTime in Line 23, and compares it with the current time based on conditions in lines 26, 29, and 34.