Awhile ago, I used a great little emitter/receiver pair wired up in a simple bridge circuit as a line detector (follow a white line on a black surface). The thing was surprisingly accurate and easy to use, but I can't remember the part number and can't seem to find it online. It was a single component that housed an IR led and an IR receiver. The casing was small, black, and quite square. You could pop the individual diodes out if you wanted.
Does anyone here know the part I'm talking about? I'd love to figure out the part number.
Hello. There are a number of such components out there; have you tried searching digikey? If you want something that's a little easier to interface with than a discrete component, you could consider our QTR reflectance sensor or reflectance sensor array. These modules are comprised of IR LED and phototransistor pairs, and they are intended for use as line sensors (but they can also be used as edge or proximity detectors).
Thanks. After some searching I stumbled on someone else's blog post that mentioned the QRD1113, just the one I was looking for! Thanks though, the sensors on your site are essentially what I'll be building, except with resistors already attached. The idea with the QRD1113 is that the unit is well tuned to get a good response curve if the students select good resistors and wire it properly: a simple task to get beginners used to building sensor circuits.
Thanks for the help, the circuit schematic on your site is exactly how I remember wiring this pair up before.