Building IR BEAM Break alarm system

First off. I know it would be much easier for me to just go and buy all this in a kit but my challenge from this project is actually building it from scratch.

The laser transmitting portion of this circuit I beleive i won't have trouble with this portion. I intend on using a IR LED with about 850nm and a variation of a laser driving circuit i found on the net.......unless somone has a better version i can study.

However, im not sure how to do the recieving part. I intend to build it so that once the light is interupted it sets off a relay. There is actually other parts of the alarm system but im just having problems comming out with a schematic for the beam reciever.

Here's what my plan is. I was going to use a PIN Photo diode since i've read that its sensitivty is the best detector with a peak range at around the same frequency of the laser. I CAN put the reciever in a pvc pipe or something to block out ambient light and external sources however i wan't to build this with some filters in it as well.

Diod-amp-filter-*****-relay

when theres a sudden voltage drop from the beam dissapearing it sets of the relay?

Anyone have suggestions on basicly anyhting i have said?

i know your prblem.
but i have solution on it.
i am giving here a ckt diagram of such system

mrkedar_kyk said:

i know your prblem.
but i have solution on it.
i am giving here a ckt diagram of such systemView attachment 19628

Click to expand...

hi,
Have you seen the date on the post.?

ericgibbs said:

hi,
Have you seen the date on the post.?

Click to expand...

Hi Eric!

I think that's some kind of record for dead thread resurrection.

Now, if the OP actually responds--that should *definitely* be a record.


Torben

Ok, I'll bring this back from the dead. I want to build a device for my garage so that when the front of the car breaks a beam, it triggers a light on the wall to turn on.

I have one of those devices that connects into my garage door but the LED is SO TINY I cannot see it when it turns on to tell me that the doorway is clear in the rear, hence my need for something bigger.

I can run wire, solder, etc, but only simple circuits. Any help would be appreciated!

hi there you obviously seem to know your stuff. im actually looking to do a similar circuit but i am unsure how the interuption of laser beam can trigger the relay. , do i have to use a logic gate to trigger the relay? i would appreciate your feedback.

shockz said:

... im actually looking to do a similar circuit but i am unsure how the interuption of laser beam can trigger the relay...

Click to expand...

You should use one of the very cheap and readily available IR receivers used for remote control in TVs, etc. Here is a thread that has links to other threads about how to do it.

cheers MikeMl, ill look into that.

Any criticism is appreciated..lol...since Im just a fool hobbyist . I'm a noob here and read in grade 10. So I've some question about this project.

You can laugh at me after looking at this image but I have no problem because Im a LEARNER so Im asking for your assistance.

NB: Another sorry for my bad English skill. I live nearby india.

Here is my questions. Look at the image, I wrote my questions on this image.
**broken link removed**