# Wiring a Working Crossing Signal for DC Operation



## Empire Builder 76 (Feb 11, 2016)

Edited for clarity.

My HO layout runs on DC. I'd like to wire a crossing signal such as the one in this link without going completely digital, if possible.

That is, no detector circuit boards. Possible?

https://www.trainboard.com/highball/index.php?media/new-crossing-signals.123324/full&d=1436201455

So aside from a required opto sensor between the ties (an edit from "digital detector", which is what I originally wrote), is it possible to wire the crossing signal so that the lights flash and can be turned on and off by use of a center-off DPDT toggle switch or some other simple electrical component connected to an AC/DC power pack (the one that controls the Tortoises on my layout) and an opto sensor? Or, is such a elemental setup incompatible with an opto sensor?

In brief: An opto sensor between the rails + a center-off DPDT toggle switch on the fascia + a power pack (using the AC or DC terminal?) + wiring to all three. Not a circuit board in sight. 

Will that setup work? Such a wiring scheme compatible with an opto sensor?

Thanks!


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## gregc (Apr 25, 2015)

if all it needs is power, figure out what voltage, AC or DC and wire it like a light bulb with a simple SPST electrical switch.

if you want to use a block detector, use it's output to control a relay if it's AC or a moderately high power transistor capable of handling the current.


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## Tom_C (Jan 8, 2016)

It seems to me (and sort of eluded to by Greg) that once you insert the "opto sensor" then you're on your way to a circuit board or something else to control the power to the signal.

The picture of the signal doesn't really show if it's already got a flash circuit included or if it's relying on a controller to provide the flashing.

What exactly is your intent? To use the switch to control the signal, or to use a sensor to control the signal when you turn the power on?


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## Empire Builder 76 (Feb 11, 2016)

Tom_C said:


> It seems to me (and sort of eluded to by Greg) that once you insert the "opto sensor" then you're on your way to a circuit board or something else to control the power to the signal.
> 
> The picture of the signal doesn't really show if it's already got a flash circuit included or if it's relying on a controller to provide the flashing.
> 
> What exactly is your intent? To use the switch to control the signal, or to use a sensor to control the signal when you turn the power on?


Tom,

You're helping to lessen my ignorance of things digital. An opto sensor, as I understand it, simply detects the approach of a train (either uni-directionally or bi-directionally). Mine would be the latter.

Your second point - to use a sensor to control the signal when I turn the power (the center-off DPDT) on/off - is what I have in mind. Will that work?


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## Tom_C (Jan 8, 2016)

Empire Builder 76 said:


> Tom,
> 
> Your second point - to use a sensor to control the signal when I turn the power (the center-off DPDT) on/off - is what I have in mind. Will that work?


Yes, it will work. The problem, however, is the 'opto-sensor'. I don't know all the different sensors available, but I will use Azatrax as an example, but I'm sure there are others. The opto-sensors as you are calling it is simply a IR pair, which is an IR emitter and a receiver that you can mount a few different ways, but they detect a train.

But here's the rub. They need some brains to do the detection, i.e. a circuit board. Here's the Azatrax https://www.azatrax.com/controller.html

There are other ways to sense the presence of a train, like with a magnetic reed switch. But, with a reed switch you're probably going to want to 'latch' the detection of the train and have the signal on for some period of time (X) after it detects the train. One term for that is 'off-delay' and you could use a latched and timed relay, and here is one I found with a quick search, but there are many others, and other ways to do the same thing. https://www.amazon.com/Timer-Delay-...ocphy=9007555&hvtargid=pla-393435320378&psc=1

And back to your signal... does it have a flash circuit built into it?

I'm certainly not trying to pour sand in your vaseline, but I've been in similar situations where you are right now, where I try to do something as simply and easily as possible, but as time goes on and I research it more I find that there was no simple or easy solution. I think that may be where you are now.

Ask more questions and maybe we can hone in onto a solution.


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## DonR (Oct 18, 2012)

The Azatrax is a very good detector system.

But here is another les costly:

https://www.ebay.com/itm/HO-CROSSING-FLASHER-and-BLOCK-DETECTOR-IN-ONE-/264100345629

Use Google search for HO grade crossing signal detectors
and you'll find more. There are photo electric and infra
red systems that many use.

With any of these systems there would be no reason
to use a fascia switch unless you just wanted to turn it
off for whatever reason.

Don


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## gregc (Apr 25, 2015)

based on your original post and the desire to have no circuit boards (?) i assumed you have a flasher circuit for the crossing. but now i'm not sure.

The flasher circuit would require power. It could be directly connected to +voltage and thru a SPST switch to ground. In other words, the switch doesn't supply power, it supplies a ground path (why?, see below).

regardless of type of detector, it needs to be capable of turning on the flasher and both the detector and flasher may be different voltages. A common approach is for the detector to turn on a transistor that "grounds" its output and could be wired across the SPST switch to ground the flasher.

optical detectors are more suited to detecting a train at a specific location unless is angled across the track and then it still doesn't cover much track. Presumably you want the flasher to go on when a train approaches the crossing some distance from either side of the crossing

it looks like the detector mentioned by Don is the NMRA type more suited for DCC that passes track current thru a diode bridge which requires a minimum of ~1.4V and will drop the track voltage by that amount.

another approach is to have multiple optical detectors across the track at least at both ends. As soon as a train crosses the one, the flasher would be on. If the train is long enough to reach the other detector while still crossing the first, the flasher would remain on until the end of the train goes past the 2nd. If the train is shorter than the distance between the detectors, the flasher will shut off, unless there is a timer circuit


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## tr1 (Mar 9, 2013)

*An alternately flashing circuit.*

A 555 timer wired up to alternately flash
The timer I/C chip should be used with a circuit board though.
For the ease with wiring.
A nine volt battery can be wired to a switch for operation.
A schematic for wiring can be found on the web.
I hope this helps you.
Regards,tr1


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## Tom_C (Jan 8, 2016)

555's are great. If avoiding work with electronics is the goal then building the circuit may be out, but would work well.

I think adding any pre-built solution (circuits) would be easy enough for most people who are already building the layouts, and this forum would be here for emotional support.


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## tr1 (Mar 9, 2013)

*Caboose marker lights*

Has anyone here used fiber optics1/64"or !/32" for caboose
lantern marker lights?
Just curious:dunno:
Thank you.


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