IR Beam Break Hardware

I am trying to make a program to detect a beam break. I am going to simulate it on Arduino and eventually move it to a Q4 board, matlab, and simulink for a class. What IR sensor/transmitter would I be looking for?

I already have these: https://www.parallax.com/StoreSearch...ir+transmitter https://www.parallax.com/StoreSearch...ir+transmitter but I'm not sure that will work. I can probably code it once I get the right sensors. Please help! Time is of the essence! : D

What sort of range do you want. This is important for the answer.

Six inches at the most. Thanks for the expertise guys.

OK you can use the circuit here:- http://www.thebox.myzen.co.uk/Hardware/Sneak_Thief.html

Im making the same thing for a people counter.

I used an IR LED, which I bought of element14, and an IR receiver module. You will need to make the IR LED pulse and the IR receiver module to only pick up light which is pulsing at the frequency you are making the LED go at. This is because if you don't, and you just use a regular IR photodiode, ambient light will affect your devices accuracy. 38kHz is the most common pulsing frequency I believe. I am using the arduino to make the LED pulse, and I bought an IR receiver module which is designed specifically for 38kHz IR light.

Check this out too. http://www.ladyada.net/learn/sensors/ir.html

But for a 6 inch range there is no need for modulation of the beam. Any problems with light interference can be solved by putting the sensor at the end of a short tube to cut down the angle. Yes for several feet range you should used modulated light, that is why I asked for the range.

I'm also interested in doing something like this. But I'll be going to use a simple LDR and a cheap laser pen. Because in the end, my pupils will have to place a security system, and I have to break in. :grin:

I'm not sure, but I think this thing would have to always be on, correct? Its not like it sucks up a lot of power anyway but, it would have to be on all the time i believe

wouternet: I'm also interested in doing something like this. But I'll be going to use a simple LDR and a cheap laser pen. Because in the end, my pupils will have to place a security system, and I have to break in. :grin:

You might not want to lead them down that path. The LDR sensor will be affected by ambient light and your students will inevitably cope with this by widening the allowable reading for a good beam, and then they'll find that the speed at which the LDR adjusts across that range to detect the beam break is slow enough that a person can just run through the beam and not be detected.

Granted it's fun to set your students up for failure, but y'know ;)

I need something like that but for visible light and the range would be about 1 foot. It would be a laser beam for the beam. Also could you put up the coding you are using for your project?