Capstone Project

raejj

Hi all,

Does anyone have experience with the IR Transmitter/ Receiver pair? I'm using it for my capstone project and cannot seem to block the light from passing to the receiver.· The connection should be made only when it passes through a hole in the spinning roller, but for some reason, due to reflection, it is never broken.· Any help would be greatly appreciated.

Thanks,
Raejj

Mike Green

You need to narrow the beam. Look at what Parallax sells as part of their IR transmitter kit. There's an opaque tube that fits over the LED. You could use a metal tube that fits over the IR LED. Depending on the size of the hole in the roller, you may need a smaller tube that fits inside the one that fits over the LED. Make sure whatever you use is opaque to IR. Not all tubing that appears opaque to visible light is also opaque to IR.

See: www.parallax.com/Store/Components/Optoelectronics/tabid/152/CategoryID/30/List/0/SortField/0/Level/a/ProductID/178/Default.aspx

raejj

I have the IR transmitter kit and am using the black two piece tube you describe. It seems to go through the opaque roller or is reflecting off the plastic casing. It's only when I cover it with my finger that the connection is broken.

Mike Green

You may need to to have a similar opaque tube on the receiving end. The roller may not be opaque.

Without a good picture / diagram and description of materials, I can't give you any more specific advice. Somehow, enough light is getting through when it's not supposed to such that it activates the detector. You have to use common sense and some experimentation. For example, turn off whatever is spinning the roller so you can rotate it by hand. See what happens to the detector output. Use various objects to block parts of the beam to see what happens.