Smart alarm system designed to detect and alert users to the presence of motion in a given environment. The system integrates a LM358 comparator, a Passive Infrared (PIR) sensor, and a buzzer to achieve robust motion detection and notification capabilities. The heart of the system lies in the LM358 comparator, a versatile integrated circuit known for its precision and reliability in comparing analog signals. The comparator circuit is employed to analyze the output signal from the PIR sensor, which detects infrared radiation emitted by moving objects within its detection range. Upon sensing motion, the PIR sensor generates an electrical signal proportional to the detected movement. The LM358 comparator processes the signal from the PIR sensor, comparing it against a predetermined threshold voltage. When the signal exceeds this threshold, indicative of significant motion, the comparator triggers an alarm activation sequence. The alarm activation sequence initiates the activation of a buzzer, serving as an audible alert mechanism to notify users of the detected motion. The buzzer emits a distinctive sound, drawing immediate attention to the presence of potential intruders or unauthorized activity. This smart alarm system offers a cost-effective and reliable solution for enhancing security in various settings, including homes, offices, and commercial establishments. Its utilization of the LM358 comparator, PIR sensor, and buzzer ensures efficient motion detection and timely notification, contributing to the overall safety and peace of mind of users.

Features of proposed system are:

• It is very cheap and affordable.
• It is efficient and portable that means we can place this circuit at any place easily.
• Very easy to use.
• Maintenance cost is low.

  The project focuses on the following areas:  

1. Characteristics of PIR sensor.
2. High voltage device controlling.
3. Buzzer working technique.

   The major building blocks of this project are:  

1. Regulated power supply with voltage regulator.
2. LM358 Comparator
3. Passive Infra Red Sensor (PIR).
4. Buzzer

   

Regulated power supply:

 

Block diagram:

video: