# School Project : Help required



## aritrap (Nov 26, 2007)

I am in class 11 and for an upcoming school exhibition have to make a project. I have decided to make an infrared based intruder detection system like the ones shown in films like Dhoom 2 and Oceans 12 and many others. It is a kind of a game in which the player will have to take a doll from one side of a room to the other end and come back without being in the line of sight of the infrared transmitters and the sensors. If the doll is in the line of sight of the beam, an alarm will be set off. The problem is that the infrared rays will not be visible to the player and as I dont want to make the game very complex I want to use some kind of a laser or LED which will clearly show the path of the infrared beams. Does anyone know something like this which does not cost much too.

Also can anyone tell me of some site which has the required circuit design for this kind of a project. 

Note: I know nothing of microcontroller electronics and I wont be using it for this project. I know only logic gates and circuits.


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## QwertyManiac (Nov 26, 2007)

Smoke should do it for normal lasers. Anything (particles) between the laser's path would make it appear. Might make your room cloudy though, so keep the amount in check, just barely enough to see them.


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## fun2sh (Nov 26, 2007)

infra_red_dude might help u. private message him


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## aritrap (Nov 26, 2007)

QwertyManiac said:
			
		

> Smoke should do it for normal lasers. Anything (particles) between the laser's path would make it appear. Might make your room cloudy though, so keep the amount in check, just barely enough to see them.



I said that I am going to red infrared. Can you tell me the cost a singel laser and its sensor. Also can you tell ,me how to produce the smoke. Also can you tell me how is is done in the films. There it is shown that if the hero wears a special spectacle, he is able to see the beams as rays. Is there any way to create such a ray which is visible to the naked eye.


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## bhutanesedude (Nov 26, 2007)

Aritrap, its good that you have a intention to do something big, and I would not discourage to do this. But our life and film is very different, why don't you just try to do something which is of your standard. I know that you can do what u have said, but it would cost you a lot, and as u have something cheap, then do some thing extradinarrily, not extraordinary things.

ANyways...I hope you will succed in what u do...All the best....


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## sashijoseph (Dec 2, 2007)

The project ain't too complex.Can be easily done with a readily available laser pointer and a photodetector.Look here : *home.cogeco.ca/~rpaisley4/ATLaser.html

Can also be done with infrared using an infrared led modulated at 38khz as the transmitter and tsop1738 as the receiver.The receiver may be mounted in a short,thin tube so that it picks up a narrow beam from the ir led.As for the visibility of the beam all you need is a 'companion' beam from a laser pointer placed alongside the ir led and pointing just adjacent to the ir receiver.
Cost wouldn't be more than 50 bucks,excluding the pointer.
Here's a crude diagram.


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## *GandaBerunda* (Dec 3, 2007)

u can use a laser (can get it locally for 90rs) and a LDR (photoresistor) and some logic gates for the project...


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## sivarap (Dec 3, 2007)

whats ur budget?

Joke: Like in the movie entrapment, tie ropes allaround...it'll be very cheap 

FYI in the movie catherine Z Jones is trained by sean connery to dodge lasers. During training he uses ropes to simulate the lasers....


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