2 Minute Laser Tripwire

About: I am robotics engineer and a teacher whose passion in life is breaking down the maths and academic jargon of programming and robotics into something that everyone can understand, primary school kids include...

Ever wondered how it is that elevator doors these days have the kindly
habit of not crushing people... well its all about laser tripwires.

We build a laser tripwire by using an LDR which is connected to an Arduino analog pin through a voltage divider. Thus the reading on the analog pin varies with the light. Next we point a laser at the LDR and write a bit of code that says if the value goes down then trip the Alarm!

Component List:

•Arduino Uno

•5mm LED

•Piezo Buzzer

•Laser Module

•Light Dependent Resistor

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    5 Discussions

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    Vwsurfer

    2 years ago

    I have been looking at all the laser tripwires and this is great for my first project, Could you please tell me how to repeat the buzzer for another 5 times please.

    1 reply
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    NE1forLearning

    2 years ago

    Lost my laser module but found the setting sun worked great for testing

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    seamster

    4 years ago on Introduction

    Very cool! I've always wondered how elevator doors and stuff like that worked. I always just figured it was magic.