# Dc train detection



## trains galore (Jul 22, 2013)

I know this is a pretty commonly discussed topic
But I have an auto reverse system which works good, but I'd like to replace the microswitch with some other non contact sensor

Does anyone know where I might be able to get a kit for an ir beam relay (so when the beam is broken it trips a relay? I have an old project diagram for one but I'd have to scratch build and i'm too lazy:laugh:

I heard about current detection too but a bit too complex for me
Did find this though which doesn't look too hard
http://www.pcbheaven.com/circuitpages/Light_Dark_Activated_Relay/
But I'd need a light above the track


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## Mark R. (Jan 26, 2013)

This may sound rather archaic, but I use magetic reed switches mounted between the rails for detection on my layout to control reverse sections, signals, crossing gates, etc. Each engine has a small rare earth magnet mounted on the bottom to trip the required circuits.

Best part ? - it works on DC or DCC as it is totally independant of any track power.

Mark.


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## trains galore (Jul 22, 2013)

sounds like a good idea
And it won't be using my track power either...
I know you can get the little reed switches in the glass envelopes, is that what you mean?
Only problem is I have to attach magnets to the trains, I could do it but I'm a bit nervous to on my best ones:laugh: I could attach something to some rolling stock though, and probably some of my old trains


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## Mark R. (Jan 26, 2013)

trains galore said:


> sounds like a good idea
> And it won't be using my track power either...
> I know you can get the little reed switches in the glass envelopes, is that what you mean?
> Only problem is I have to attach magnets to the trains, I could do it but I'm a bit nervous to on my best ones:laugh: I could attach something to some rolling stock though, and probably some of my old trains


Yes, those are the reed switches. To install the magnets on my own engines, I drill a shallow hole (the magnets are only 3/16" diameter) in either the bottom of the fuel tank or in the trucks gearbox cover on longer engines (so the magnet stays centered between the rails) and glue in place with a bit of epoxy. Be sure to use the rare earth magnets as regular magnets aren't strong enough to trip the reed switch if moving too quickly. I got my magnets at Radio Shack, but I'm sure there are other sources.

When visitors bring over their own motive power to run, a stack of two or three magnets stuck to the coupler box screw works in a pinch. The magnets are also a perfect fir into the opening of a freight car truck sticking to the truck screw. I have a couple dedicated "magnet cars" for when there is no provision on visiting power to attach the magnet.

Mark.


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