I purchased a digital sound module from Innovative Train Tech that will play a fog horn and other harbor sounds as either a continuously on cycle or a momentary one-minute tract. I want to trigger the sound for as long as a train is running through the harbor area on my layout and I am looking for suggestions, with specific circuit designs, for how to build either an open collector analog circuit that would be triggered by IR sensor or some sort of block detection device that would do the same thing.
I suspect there are commercial products available which I wouldn't be against purchasing, but I'd like to try to build it myself and this forum has a lot of "engineers" with a lot of good ideas.
John
Check the circuits available from this web site: http://home.cogeco.ca/~rpaisley4/CircuitIndex.html
The first thing that comes to mind is reed switches and magnets.
Here is a link to some detector circuits.
Rob Paisley's MRR Electronics Pages
Edit: LOL cacole beat me too it!
I'm in the process of putting in some train detection circuitry using reed switches from Miniatronics. So far, it looks like this will work very well. I'm using it in what will be underground staging for my subways.
This is a good use for reed switches because the number of trains that will be on those tracks is very limited. I only need to equip 2 trains with magnets. Of course, magnets are cheap. (It's the reed switches that run up the cost. Even so, the Miniatronics package of 5 switches and 5 magnets is only 9 bucks.) So, you could get cheaper magnets to equip your whole fleet.
It takes an iron man to play with a toy iron horse.
FYI Magnets.
Rare Earth Circular Magnets
Rare Earth Rod Magnets
Rare Earth Magnet Sampler
Thanks for all the tips. The websites have good information including circuit diagrams. I also found that Dallee (www.dallee.com) has a block detector for $30 that would make it a lot easier than trying to mount IR sensor/detectors.