Cheap Optical detection

[rsn48]

In the modified helix I am building I'd like (there are four levels) some form of detection so that I know the trains are still moving.  I figure 3 or 4 detectors per level.  So far I have come up with this solution, any other suggestions:

http://www.azatrax.com/ir-model-train-detector.html

[LKOrailroad]

If you are handy building your own circuits you can build your own for a lot less $$.

http://www.trainelectronics.com/artcles/PulsedIR/index.htm

The pulsed system is good when used in areas where there is likely to be stray IR sources. Inside your helix that isn't likely if you shield your photoresistor properly. That lets you build an even simpler circuit.

[LKOrailroad]

How is this for a sweet simple inexpensive solution? Details here: http://home.cogeco.ca/~rpaisley4/IrProximity.html

[rsn48]

I've sent this to a friend of mine who is an electronic type, but I must say I find the print on my computer at the site below to be difficult to read:

http://home.cogeco.ca/~rpaisley4/IrProximity.html

[John]

what I like about Rob's circuits is that he uses the same common parts for most of his projects  so you can go to digikey , allied, or jameco and get a bulk pack resistors, 4148 diodes, and use them for other stuff .