For a while now, I have been investigating ways of using IR (Infra Red) for detecting trains on a layout. I am happy to say that I have found a good low-cost solution using the IS471 chip from Sharp that is quite easy to assemble. Here is an article that I have written about it on my web site.
The good news is that it works well and costs only about $3.50 per detector. This is considerably cheaper than IRDOT which costs almost 10 times as much. I can defintely recommend this approach.
Anand
Slowly building a layout since 2007!
The article appears most thorough and the approach looks worth investigating when the time comes. Thank you for posting it.
Dave Nelson
ndbprr wrote:I wasn't aware that IR would bounce off a plastic object. For my staging yard throat I intend to use one detector for all the tracks by shooting across the throat. I am going to mount the emitter with a tube around it to focus the beam better when shooting at the detector on the other side. Hopefully it will let me know when any track is fouled.
Actually, as I described in my article, I found that plastic does not, in fact, reflect IR very well. I actually had to use a little bit of aluminum foil on the locomotive or freight car to get the detector to trigger. The only exception were some Athearn Ready-To-Roll freight cars. There are a few very shiny screws on the underside that act as nice IR reflectors :-)
The setup you describe ought to work fine. Having the train block the IR beam is pretty fool proof.
Chip
Building the Rock Ridge Railroad with the slowest construction crew west of the Pecos.