I'm trying to make a simple IR break-beam circuit to activate an LED. So when someone breaks the beam, it will activate an LED on a timer (simple 555) and the LED will turn off once the timer has expired. I understand the timer part, but I have no idea how to go about using IR LEDs to activate separate circuits. I suppose a phototransistor would be the receiver, but I don't know how to use it in this context. Can anyone supply a diagram or some information on how to approach this? I'm trying to make this very simple so that I can understand the basics and then go from there. Thanks.
You're in luck, I just stumbled across this circuit while searching for other ideas, and happened to book mark it for a later read/make. http://www.discovercircuits.com/H-Corner/infraredltsw.htm Unfortunately, that's about all I can offer for help with the actual making of it, aside from my good wishes, and hopes for pics of the completed process!
Thanks, but that seems a little more complex than what I'm going for. I simply want to make a circuit where, when the phototransistor no longer detects the IR LED (i.e. something interrupts the path), then an LED is activated. I think this could be straightforward using a few transistors, right? I'm not sure, though--I'm looking for some suggestions because I'm new to this sort of thing.
Heres something I whipped up in a min: the idea is when IR light is shining on D1 (your ir detector) the resistance drops allowing the base of the transistor to turn on. It begins conducting and the LED switches on. Thats the idea anyway.
I hope you find the circuit your looking for. I've been looking for pretty much the same thing for quiet some time now. When I look to the commercial industry the prices are extraordinary. There couldn't be anywhere near that much in $ in internal parts involved. Besides the feeling of Do It Yourself is priceless. I'm looking for a simple circuit design that would use a pulsed IR beam (to reduce false alarms) that can be extended in range 100 to 500 ft by using optics such as from binoculars (separated to make 2 optical receivers) that can be found at The Dollar General Store $10 bucks . Another approach would be one of the 3 watt IR LEDs on the market or possibly combine the binoculars and 3 watt IR LED for super range. If you have any luck of course please let us know. Wishing the both of us luck From Imjusthappytobehere
Here's some easy and functional circuits (Designed for model RR) Based on a comparator - works great with photo transistors. IR Proximity More background info.... Photo Dectors There is an "Across the track" sensor on the site using a laser pointer lots of good stuff there...
