This circuit was placed inside the PIR sensor, and the phone jack was installed in the lower part of the case. Resistor R4 is attached to the PIR LED driver.

This circuit is from the GLOLAB web page. The document referenced here includes an excellent design as well as an excellent tutorial on PIR devices. You've probably seen these ...

PIR LED Security Light Circuit Schematic Notes The PIR sensor requires an initial stabilization time of about 10 to 60 seconds in order to function properly. During this time, the sensor gets familiar ...

This is a simple update to Mr. Hareendran’s PIR Sensor Security Light circuit. It has a shortcoming limits the relay voltage to approximately 3.3V. While this may function with some 5V relays, it will ...

The PIR sensor is housed in a shroud to limit its wide field of view; [Jeremy] added a second shroud when an even narrower field is needed.