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No security system is complete without lasers. We have all seen movies where the main character has to get past a high tech security system and there is always a room full of lasers somewhere.

So in this project, I show you how to build a laser tripwire alarm.  All you need is a cheap laser point, a couple of mirrors, and a few dollars of electrical parts. With this you can cover an entire house with an array of light beams. If any one of them is crossed it sets off your alarm. And unlike in the movies, these lasers are practically invisible.

This system is fast and easy to set up and it is battery powered. So you can set it up anywhere. You can make this a standalone alarm or it can be integrated into a larger DIY security system like Make’s Cellular Sensor Sentinel.

Read all about it on MAKE: Projects and on Instructables.

See the full series here.

Jason Poel Smith

Jason Poel Smith

My name is Jason Poel Smith. I have an undergraduate degree in Engineering that is 50% Mechanical Engineering and 50% Electrical Engineering. I have worked in a variety of industries from hydraulic aerial lifts to aircraft tooling. I currently spend most of my time chasing around my new baby. In my spare time I make the how-to series “DIY Hacks and How Tos.”


  • Quinn

    Please! Leave the parts list!

  • eliobou

    Nothing is say about R1 resistor. What is the value ?

    • http://none not cleaver

      R1 = 10 ohms
      R2 = 1K ohms

  • jose

    My kid and I are total novices but this looks simple and fun. Could you list the parts needed please?

  • svaughn

    what part number is your photo resistor?