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Laser Door Security Alarm DIY

how to make laser security alarm

Welcome to the Quanta Project, In this project, we will make a laser security alarm. Every time we need security in our office, school or our home as well. so we decide to make a laser security alarm with a simple technique using Laser and the LDR driver circuit. it is the cheapest project you can make this laser security alarm in just $1- $2.and it is very useful and easy to implement and you don’t require anything expensive like computers and tools etc. so to make the projects first we will learn the working of this project. how it works and the reason behind it. and how to troubleshoot the system. Laser security you just saw in the movies. we are exactly making the same there will be laser pattern to secure the particular place from the unauthorized access. you will just make it in 1-2 hours.

How it works.

It works on the principle of LDR(light dependent resistance). It is one sort of resistor whose obstruction fluctuates relying upon the measure of light falling on its surface. At the point when the light falls on the resistor, at that point the opposition changes. These resistors are regularly utilized in numerous circuits where it is required to detect the nearness of light. These resistors have an assortment of capacities and opposition. For example, when the LDR is in murkiness, at that point it very well may be utilized to turn ON light or to kill a light when it is in the light. A run of the mill light ward resistor has opposition in the haziness of 1MOhm and in the splendor an obstruction of two or three KOhm.

Components Required:-

  • Laser light
  • LDR
  • NPN Transistors
  • Resistors
  • Battery
  • Wires

Circuit diagram:-

There are two transistors in the circuit as you can see in the circuit diagram. Two NPN (BC548) transistors actualized in this security alert circuit as an exchanging gadget. LDR (Light Dependent Resistor) associated with the base terminal of Q2 transistor through R4 resistor this LDR gives low obstruction when the laser light falls on it and gives high opposition when there is no laser light because of that supply voltage to the Q2 transistor changes relies upon the LDR obstruction.

The Q1 transistor authority terminal is associated with ringer and Indicator LED and afterward base terminal of Q1 transistor associated with the Q2 transistor gatherer terminal. Every transistor needs some edge voltage to get turn ON, If the laser light falls on LDR it enables supply to the Q2 base thus it becomes turn ON so the Q1 transistor base doesn’t get any inclination, because of that Q1 transistor remains in OFF condition so the signal and LED likewise in OFF condition

At the point when the laser light blocked then LDR went to high obstruction and there is no voltage stream to the Q2 transistor base so the Q2 gets killed however Q1 transistor base gets supply through R3 resistor and Q1 gets turned ON, so the signal and LED likewise gets turn ON and gives ready sound and Indication.

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Written by shahid

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