Signal Relays

So this being a discussion forum...

Let's take as a given that Scaletrax switches "weld" the outer-rails together which for sake of discussion means you can't have a switch section be part of an insulated-rail trigger section.  To be clear, this is a premise of the following ramblings:

Backing up a bit, this is the "classic" occupancy detection problem where you can't place enough sensors to fully span/cover the length of rail of interest. The insulated-rail method is so simple and inexpensive as to be elegant!  But if that's not in the cards, here are 2 ideas for consideration.

Method 1) From the HO or 2-rail world, one approach to occupancy detection is to detect center-rail power consumption in a block.  A block can include switches.  Power consumption is via a current-sensor which triggers when the block current exceeds some threshold...say, 0.1 Amps.  This method typically means placing a powered caboose (or whatever) at the end of the consist.  The 2-rail guys know about the special 2-rail wheel axles that have embedded resistor that draws power and can be placed in unpowered cars.

This is of course just a half-baked idea.  Even with off-the-shelf current-detection modules there is homework to be done.

Method 2) From the 2-rail (and 3-rail) world, if impractical to install a detection method that spans the entire trigger section, then point-of-detection sensor can be augmented with a timer to extend the trigger.  It's not fool-proof of course but can work in many applications.  For example, optical detectors like the Lionel 153IR or MTH ITAD detect occupancy at one point and then extend the trigger output electronically to simulate occupancy detection over some length of track beyond the sensor.  Multiple sensors can be tied together to cover a wider span; the classic example of this is a sensor on both sides of a grade crossing to trigger the signal from either train direction and to hold the signal active until the train exits the other side.

So for the matter at hand, the switches would have to be isolated from the insulated trigger sections with additional cuts/gaps.  Then multiple trigger islands would be tied together.  For the special case of running a short-consist or a lone switcher engine that could completely reside on just a switch section, a timer can extend the trigger by, say, 5 seconds to allow the consist to reach the next island without the trigger momentarily disappearing.

Like method 1, this is a half-baked idea.  One thing going for this method is the existing setup already uses 12V DC relay modules and there is a source of 12V DC.  There are many inexpensive 12V timer modules that could be enlisted to provide a settable time-delay to extend the trigger duration.  For example, from eBay or Amazon:

Or a DIY'er comfortable working at the component level could cobble together a 12V DC trigger extender for less than 50 cents using a handful of garden-variety parts (resistors, capacitors, diodes).

Hi Stan, so if I isolate the switch and just add drops to the relay it should work?

@mike g. posted:

Hi Stan, so if I isolate the switch and just add drops to the relay it should work?

By "switch" this would mean "switches" plural.  By "it should work" simply tying drops to the relay as shown in the diagram means it would work if a consist is long enough to span the switches.

If as you mentioned you run a lone switcher engine (yeah, how inconvenient that switcher engine and track switch sound alike) you would get the following situation:

The short consist or lone switcher engine approaches the bridge.  It hits the insulated rail section and the signal changes from green to occupied.  But when the consist reaches the track switch and no longer is over an insulated rail section, the signal changes back to green.  Then it reaches the next insulated rail section and the signal again turns to occupied.

OTOH, if your consist is long enough that it straddles the switches, then you won't see this awkward behavior.  Agreed. This is very confusing.

I suppose you could simply do as you suggest.  In other words, cut the additional gaps.  Then mess with the configuration and see if/how annoying it is when a short consist enters the configuration.  If it's simply annoying and you're pulling your hair out, then I will give you exact instructions on how to thin your wallet by $10 or so to insert timer-relay modules to resolve what should be 99% of the cases.

Thanks Stan, it will probably be tomorrow before I get back out to the train room!

Morning guys, I have a couple questions, first off which diagram should I be using? they are both different. Here are the 2 I have from here.

Also here is a photo of the relay I am using.

The white wires with the green and red tape are the wires that go to the isolated section of track. It outer track works in on direction but when a car enters in the other direction it turns on the red light facing the car, not the other side of the signal bridge.

I am so stuck on this, I am thinking of starting all over and forget it ever worked on the office floor!

a couple more photos for your enjoyment! LOL

The first one is with nothing on the track.

There are 2 different diagrams because there are two different applications/discussions going on.

The upper diagram is for the bi-directional application which is more complicated, requires more relays per track, and so on.  The lower diagram is for a basic 2-aspect signal where the signal turns Red when a train is on an insulated rail section.

In your last photos, it appers the main-line on the RIGHT track (I assume this is what you call the inside loop?) has a Red signal even though there's no train in sight!  Irrespective of which application, that typically means there is a short that is connecting the insulated-rail to the outer-rail.  As I recall, the inner-loop has turnouts/switches that "short" the outer-rails.  If these are not isolated from the insulated-rail sections (in other words, the cuts/gaps are not in place) then I can see how this might cause such a short.

Thanks Stan, so here is another question, using the relay board I have can I still do bi-directional with what I have?

If I understand your question, yes.  One bi-directional signal requires 4-relays and the somewhat tedious interconnections as shown for a 4-relay module.  Since you have two loops, you can use 4 of the 8 relays for one loop, and the other 4 for the other loop ... crudely depicted in above cut-and-paste.  You must make all the interconnections - I suggest "working" on one loop (4-relays) at a time.

A single 12V DC wall-wart as you apparently already have is more than adequate to power the 8-relay module (or two 4-relay modules if you go that route).

Hi Stan, First off thank you for all your help! between you Leo and Chris a. I was able to get everything sorted out this morning and working perfectly! Here are a couple videos for you to see.

You have to look really fast and close at the start of the next video to see the green light turn red!

It works going both directions, take my word for it! LOL Again thank you guys so very much! It's been a long 2 weeks! LOL

Looks like a lot of action on your layout.  Good thing you have bi-directional signaling to keep things in order!  Your safety inspection officer should be happy.

Thanks to you and all your help!

Mike: Good work! Your persistent attempts at this have paid off! Well done!

@Consolidated Leo posted:

Mike: Good work! Your persistent attempts at this have paid off! Well done!

Thanks Leo, like I said I couldn't have done it without all your help!

Very nice Mike. Signals add more realism to model trains.

Bob

@RSJB18 posted:

Very nice Mike. Signals add more realism to model trains.

Bob

Thanks Bob, I have a couple more, but I am going to take a break from that. It kinda fries my brain. Plus if I run into a problem it gives these guys a break from me! LOL