Picture of Another Arduino Laser Tripwire
This is my version of login258's laser tripwire at http://www.instructables.com/id/Arduino_Laser_Tripwire/

I've made a couple of modifications: the laser is now independent from the Arduino so that it can be placed anywhere in the room and I've changed the LED to a buzzer.


Step 1: Parts

You will need:

Laser emiter, 3v battery and on/off switch OR Laser pointer and electrical tape

Photocell (a big one because it makes an easier target)
2 10k resistors
peizo buzzer
Battery to power the arduino with a jack
Various short jumpers
Elastic bands
Bored kids
Wet sunday afternoon
andr3w992 years ago
Can someone make an instructable to help me run a code on an Arduino Uno? If would be very helpful! Thanks.
(I need fully detailed steps)

1 start Arduino IDE
2 open code you want
3 connect Arduino to yr computer with USB cable
4 in IDE select under 'Tools' the proper port and board
5 press 'upload' in yr IDE

andr3w992 years ago
Is there any code needed to make this work? Or can I just set it up & it will work?

yes you need code, otherwise the arduino has no idea what you want

Xanderone1 year ago
I can't get easy access to cheap laser pointers in my region (west Africa) but I sure have hundreds of faulty CD and DVD players lying around. Could I make use of the laser module inside these players? If yes, would I have to remove their lens system or just use it as it comes? A quick answer will be appreciated.
devilmaycry3 years ago
do you when the beam is broken, does the buzzer keep on buzzing or does it tur off after a while
Jonathan Robson (author)  devilmaycry3 years ago
yes it turns off
Login2586 years ago
Thanks for the credit! I'm glad my Instructable actually made some sort of impact. Someone commented on mine and said that two photoresistors would work well, one for ambient light and one for the laser, so that's a good suggestion for you .
Mr Login258......I just stumbled onto your little experiment. I have a need and I figured you seemed a lot smarter than I and could tell me if it is possible, how small could the devices be and how much would each cost? I want a laser beam that goes between 20" - 36" or maybe even 48" and when broken makes a noise. I need small....maybe the laser in one section and the "guts" in another place? Cost......are we talking $5, $10, $25 or $50? How do lasers perform outside; wind and sun? My email is rjones.chodrowrealty@gmail.com.........Dinner on me if you can help.
why not buy the arduino board and just get atmega's perloaded witht the bootloader.
make your prototype and look up for rrrrrrb arduino
slder the connections and you will have it ready for abt 10 $ max
Grey, I spent about 50 dollars on the supplies for this whole project including an Arduino Uno (official version from Arduino) to make this. A green laser could go VERY far, lasers are not affected by wind/sun or anything. My cheap $2 red laser can definitely go about 200-300 fet.
You could make one pretty cheap. Well really, it depends. For the first one it might cost $50 total, but after that each would be less than $10. Only because the tools needed to program the microcontroller are a bit pricey. Distance isn't a problem, and it could be about the size of a thick cellphone (receiver) with a completely separate battery powered laser unit. And dinner definitely isn't required for my help.
Jonathan Robson (author)  GreyGriff6 years ago
Beats me. I live in Shanghai. I get them for about 3 dollars at the electronics market down the road. Wind doesn't affect lasers. Sunlight does. At night I lose sight of it after about 3 blocks.
Another thought is that since this is probably going into a case of some sort, drill a hole in the case for the photoresistor, and recess is into the case a bit so that ambient light is less of a factor.
Jonathan Robson (author)  inventorjack6 years ago
Yes, recessing makes it a lot more flexible as to where you can place it.
TOCO5 years ago
is there a way to make the buzzer turn off when someone crosses back through the trip wire. That way if it is used for security it wouldn't turn off until the person leaves.
asirota TOCO4 years ago
Of course there is. The sketch needs to hold a counter in memory that gets switched once and switched again and set the pins appropriately to control the buzzer. Very possible, but the software is different.
jm18205 years ago
Thanks for the very helpful instructable.
Just wondering, if I could seperate the photocell and Arduino board, by about 20 metres (using wire) ?
Its just that I want to have the photocell at the top of my driveway, and the buzzer inside my house.
I have no idea, if a length of wire, would affect the voltage output of the photocell - anyone have a clue ?
dodich jm18205 years ago
Why not place a reflector 20[m] away and keep all the electronics together. Just a thought.
gaurangb6 years ago
dear from where i will get circuit for install photosell and buzzer to dedtect beam braking conditions. gaurangb@rocketmail.com
did u get the arduino at the maker shed or some were else and did u kno u can get an arduino mega it is so good i want 1.
what are the benefits from the arduno mega to the denou...(dont know its name)
it has many more pins and has more other pinsim not an exbert so goto http://makezine.com.com/ for more info

p.s u need to look in the podcasts to find the 1 a little tricky to find
oh right did not know that thanks
there is evan a vidio lol
amando966 years ago
i placed a thermistor instead of the LDR, now i have a very sensitive temperature diference measurer :D next step, get an LCD, and make thermometer :D