This document describes a simple dark detector circuit using an LDR (light dependent resistor) that can act as a mini police alarm. The circuit uses an LDR, resistor, transistor and a buzzer or LED to create a sensor that will sound an alarm if the LDR is exposed to darkness, indicating an intrusion has been detected. The circuit requires a 6-9V DC power source and creates a simple intruder alert system with few components.

1. Simple electronic Dark Detector or Sensor circuit using LDR
DC 6-9V Mini Police Alarm