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Laser Light Security Alarm using LDR | Burglar Alarm

Hello engineers, In this article I am going to share an LDR operated laser light security Alarm system. This circuit having LDR as the light-sensing component. This circuit discussed here has a relay that simply changes whenever the laser falling over LDR is interrupted and then Buzzer turns ON.So let’s get started with understanding in detail. with our Laser light security alarm circuit or Burglar alarm.

Materials:

  • Laser Light
  • RL1-Relay 12V dc
  • Q1 -Transistor TIP122
  • R1-470K
  • LDR1-LDR
  • BUZ1-BUZZER 12V
  • PCB
  • BATTERY /POWER SUPPLY -12V dc
  • D1-LED

The Circuit for laser light security alarm

Laser light security alarm

In the circuit above the Laser light is falling over the LDR. An LDR is a photoresistor whose resistance is least when the incident light is at the high intensity and highest when kept in dark. So, when the laser is falling over the LDR, its resistance is least approx.100ohms which makes the transistor base to be shorted by ground and transistor is kept turned off and the relay is also turned off and the buzzer is also not getting supply.

When Laser is interrupted

laser light security alarm

When Laser is interrupted, Light is not falling over LDR and LDR’s resistance is maximum, up to 1M ohm which is higher than R1 which is just 470Kohm and lesser than the LDR’s resistance 1Mohm. So, now the transistor’s base is connected to +12v via 470k resistor (because current follows the easiest path) to travel through. The active state transistor turns the TIP122 which turns ON the relay and then com is connected to the NO. This condition connects the Buzzer +ve and -ve both terminals.

Applications Of circuit

These kinds of circuits are employed in various security systems,

  • Theft alarm systems,
  • Field security
  • Cattle herd protection system
  • Burglar alarms,

It can be employed in field boundaries to automatically turn on fence gates at night to protect crops, etc.

I hope you guys liked it. Comment below to share your views.and ideas. Below is a full simulation video check that too.

Watch full simulation video and do subscribe to that channel for getting updated about new circuit diagrams ,simulations and gadgets because there are somethings i only upload there

Check a much More advanced smart automatic Intruder detector Burglar alarm with 400metres loud sound and motion detection feature. Circuit here. Also having additional functionality of auto power on and off during night and day.

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Aabhishek
Aabhishek
Aabhishek Sharma is a Computer Science Engineer and a Digital Marketing Trainer and Consultant. Aabhishek Sharma also loves working on Electronics Projects and working with microcontrollers and Designing Home automation Gadgets.
http://www.electroinvention.co.in

18 Replies to “Laser Light Security Alarm using LDR | Burglar Alarm

  1. Very good info. Lucky me I recently found your site by accident (stumbleupon). I’ve book-marked it for later!| а

  2. Hmm is anyone else experiencing problems with the images on this blog loading?
    I’m trying to determine if its a problem on my end
    or if it’s the blog. Any feed-back would be greatly appreciated.

    1. Hello, Sorry for the inconvenience but everything on the website’s end looks fine. It can be either your internet connection or maybe some technical issue on the website, a lot of users come so sometimes it can be a server problem too.
      If images are loading after you are scrolling that part and not already load when you aren’t viewing that part of the page, then that’s a lazy loading plugin feature. to decrease page load time and also it saves your internet data too.
      If my users are facing problems then I am going to remove that. Please update if anyone else is also facing any problems.

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