I am looking for help with making a simple infrared break beam circuit. What I need it to do is this. When something gets in the way of the beam and breaks it, it will turn a switch on. When the beam goes unbroken, the switch turns off. It will need to be able to cycle fairly quickly (about 15 times per second). It also needs to be relatively small. I would like to avoid using a relay for the switch, because the design will see lots of vibration in use. The switch won't need to handle much power either, less than 9v and maybe a hundred miliamps max (I'm not sure exactly how much, but I know it won't be much). Any help would be awesome. An actual circuit diagram is preferred, but ANY help or pointers are appreciated! Edit: I forgot to mention that this will be used in a dark place, so light interference shouldn't be a problem. If on the other hand you know how to prevent light interference and want to share, by all means do! It would be great just to know.