detection device

[glsummers]

Is there any kind of electronic detecting device that you can put under the track to keep two trains from colliding into each other at a 90 degree crossing where one train will stop and let the other train go through automatically? Thanks

[WoundedBear]

Would something like this from MicroMark work?

http://www.ares-server.com/Ares/Ares.asp?MerchantID=RET01229&Action=Catalog&Type=Product&ID=83232

Sid

[glsummers]

wounded bear,
That would tell you when a train was passing over the light but I don't believe it would stop the train automatically and let the other train pass by the 90 degree crossing. Maybe there is nothing like that available. I just thought I would ask some experts that have a great deal of knowledge in this hobby. Larry

[sour rails]

     Something like that would be nice to have, but there would be one problem, the detector would be too close to the crossing.  In reality, there would be some distance still travelled before the loco would finaly stop, not just instantanious stopping.  In railroading, You are the engineer of all your trains.

[Jim Banner]

Larry, it gets pretty complicated to do it automatically.  First, you need four detectors to tell if a train is approaching from on of the four directions.  And the detectors have to be able to tell you when the train has cleared the crossing.  A couple of  Circuitron DT-2 detectors might work.  http://www.walthers.com/exec/productinfo/800-5202

Then you would need a lockout system so that whichever train reached the crossing first would maintain command of the crossing until it had completely cleared.  This could be done with a pair of relays, each one controlled by one of the DT-2 detectors if and only if the other relay is not already pulled in.

It would also be nice if the trains slowed to a stop when necessary and also speeded up smoothly.  This could be done with decoders that include a "stop on dc" function if the railroad was being run on DCC.  With dc, you would need some special circuitry to do the job.  Maybe Circuitron makes something suitable for this too.

My non-automatic solution is much simpler.  Use a toggle switch to shut off either one route or the other.  This is just a safety device in case the engineer forgets to watch for other trains.  No gradual stop.  No smoothe accelerations.  But most important, no crashed trains.

[glsummers]

Thank you all for your input; I believe that is a little over my head. I believe having a simple cutoff switch would be the ticket as Jim suggested. I was just being lazy and wanted to see them run without having to be on my toes when running three or four engines on my DCC system. Thank you all again for your suggestions. I sure enjoy this message board. You all are great. Larry

[r.cprmier]

Four infra-red detectors[electric-eye type] similar to what is used in a garage door circuit, operating respective contactors, would do it.  A manual reset type of circuitry (start button) would probably suffice for a restart, to re-(de)energize the contactor.  "Cosmetizing" such devices should be no real feat, unless you are modelling the desert or a pizza pan.

Rich