Introduction: Self Calibrating Laser Trip Wire

Picture of Self Calibrating Laser Trip Wire

this is my tutorial on how to make a self calibrating laser trip wire .

WARNING lasers are super bright and will blind you. so don't use them were there are kids or in public spaces!!!

Step 1: What You Need

Picture of What You Need

  • Arduino (any should work)
  • 5v buzzer (if you buy one that uses pwm you will have to change the code a little)
  • laser (i'm using one from adafruit)
  • 10k resistor
  • and a photo resistor

Step 2: Wiring

Picture of Wiring

not a lot to say about the wiring, just copy the diagram

Step 3: Coding

Picture of Coding

download and run the arduino code, to program the board

Step 4: Calibration

Picture of Calibration

the arduino calibrates itself at start up and when you press the reset button.

to calibrate it, align the laser beam up with the sensor like so.

then press the reset being careful not to move the laser or the board.

done, now the system should be armed. you can test it by braking the beam with you hand.

does the buzzer trigger? if so you have correctly set up the system!

Step 5: Mounting

Picture of Mounting

ounce you have it working you can mount it using blu-tack .

it works best inside or in the dark. it will not work in direct sunlight because it will over power the laser beam giving false readings.

Step 6: Taking This Project Further

you can take this project further by bouncing the beam around using mirrors to make a massive laser grid.

or reprogramming it to count the number of people walking though,

or even use it for a automatic nerf gun trap!


Hazbell vids made it! (author)2016-12-09

thanks for the totorial very simple great for people who are learning I didn't have a buzzer so I used a led. There is a delay but I can fix the code for that. I am 13 and learning arduino and this was good to learn about photoresisters as well ??

DeadEye200321 made it! (author)2016-06-21

Thanks for making this tutorial, it was very simply and easy to do unlike the others that people make, they're a little more complicated. I liked this because I didn't have to go buy parts because I'm 13 and us teens like to spend our money so I don't have money to buy parts, LOL. Thanks for the tutorial :)

lieg (author)2015-07-29

can some body put the code what is inside because my computer cant open it pls

WoodsyTECH9 (author)2015-03-30

How would the code change for a peizo buzzer?

WoodsyTECH9 (author)2015-03-30

How would you change the code to work for a peizo sound speaker?

slattermatter (author)2014-03-27

"it will not work in direct sunlight because it will over power the laser beam giving false readings." - Do you think it would work in direct sunlight if you used a infrared laser with a infrared filter over the photo resistor? Infrared filters block all visible light letting only infrared light pass. This approach will be harder to calibrate but it will be invisible to humans and can be setup outside for surveillance or even a wildlife camera.

wfoster6 (author)slattermatter2014-03-28

you could just mount it in a shadow were the sun cant shine in on it .

but yes it would be possible to use ir although you would have to use a ir sensor

Very cool!

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