I am a novice / hobbyist and I have a project in mind that involves detecting where a laser is aimed at on a relatively large scale (300+ sensors). I've found circuits that would work on a small scale such as a phototransistor or a comparator IC to compare resistances, but I have absolutely no idea how to scale this up in a cost effective manor. This will be used to then output digital logic signals to a microprocessor. Any ideas?
you could assemble a photo-resistor array, if you're looking for a cheap, small, precise measurement of the location of a dot. You will need a number of Input equal to the number of rows + the number of columns, wired up like so:
You can buy a hundred of these for about 10 cents a piece, probably less, and make a 10x10 matrix for 10 USD.
if you don't need that sort of precision, I agree with ambitoise, and check out some image recognition solutions.