My super-junction signal wiring

Model Railroader Electronics and DCC
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This might not be prototypical, but I designed a signal system for my double-turnout junction. 2 signals for entering, 2 for exiting, and 2 for staying in the loop, for each direction.

Only one light at a time stays green, while all others are red, controlled by Atlas momentary button control.

It also controls the 2 turnouts and their frogs.

I bench tested the system, and am about to assemble it all.

The direction and signals 2/3 switches, I’m actually going to build latching transistor switches instead of the mechanical ones.

I’m not an electronics expert, so I hope this, even if not perfectly clear, makes sense.

Cost: next to nothing! :slight_smile:

Edit: On my computer it showed an older version of my drawing in this post, so I reuploaded it.

Double-turnout signal wiring

2

The Atlas switches and controls will be on 12V, and the relays and LED’s (with resistors, of course) on 3.3V.

I made the signals with my 3D printer. Most wiring is phone wire.

My trains run on DCC, but this all will be running on it’s on power source.

3

what does enter, exit and pass mean?

could you indentify the turnouts, normal and reverse positions, in the photo and the diagram.

seems that in one case, all 4 turnouts need to be switched, and in two other cases (crossovers), 3 need to be switched. yet there are six possibilities.

what do you mean by latching transistor switches, do you mean a monostable? have you considered latching relays, or an arduino?

4

Actually you can make it very prototypical with one simple change.

As you approach a turnout, all signals should be on the right, or engineers side of the track.

The prototype would have the two heads on one mast, with the one for the straight thru route on top.

Green over red would indicate clear for the main or straight route, red over green indicates clear for the diverging route.

This is a standard prototype interlocking signal, simplified a little bit.

Sheldon

5

Am I missing something? I only see two turnouts and a crossing?

Sheldon

6

I’m at work, so I don’t have time to give a full reply until late tonight or in the morning.

This junction is located on the lower level of the train table. You would enter from the upper level, exit to the upper level, or just pass through the area. That’s what I meant with enter, exit and pass.

There are indeed two turnouts. Six approaches: going straight, turning out, and coming in from the side track, in both directions. There is no reverse loop.

The way it’s wired, sliding (for east/west direction), and pressing appropriate momentary button will give the green light to that given approach, and turn the other 5 lights red. The action will also throw the turnout switches accordingly.

The two turnouts are connected together, so when turnout “a” opens or closes, turnout “b” follows suit. Same for the other signals, when any of the other signals are turned green, the turnouts will throw to proper position.

As for the prototyping, might be a lot of work to mod at this point, but I will definitely look into it and change it now or later on at some point.

Thanks all for the replies/comments, greatly appreciated! I will reply more later.

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With latching transistors, I meant this:

https://circuitdigest.com/electronic-circuits/simple-latch-circuit-diagram

There are 4 switch throws in the picture in the original post. Two of them are attached to the tracks, as they are supposed to be. The other 2 function only as toggle/latch for the 3-pin limit switches. I could replace the limit switches and their latching mechanisms with transistor circuits.
I know of Arduino boards, my 3D printer uses one, but I am not familiar with them, and don’t know what they can do and how to use them. Also, the cost could be a factor, I am on a low budget,

8

I won’t try to explain every detail of the workings of it here, maybe I should make an article on my website, or make a YouTube video later on. But maybe this will help:
The red signal LED’s are always, by default, powered, on each signal, unless switched to the green LED, by the 5-pin relay.

Sliding any of the momentary buttons on the control either left or right, and pushing it, will send power to the relays for either the 3 west side or 3 east side signals, depending on which direction you slide the button. That is the function of the Direction limit switch, manipulated by the remote switch throw.
Which one of those 3 signals will switch to green, depends on if you press the Enter, Exit, or Pass momentary button, by means of connecting the corresponding relay to ground, and disconnecting the other relays from ground, while at the same time, switching the turnout tracks, and reversing the frog polarities.
Well, it is kind of hard for me to explain, but it does work .

9

i didn’t understand why there are 4 switch machines.

i assume that since you’re using diodes, the momentary buttons are used to select a route, not specific turnouts. But there’s no need for diodes. One Atlas turnout control could be used to switch both turnouts to either their normal or diverging routes.

and aren’t there only 3 signal aspects:

  • on the tracks to the crossovers: either stop (red) or clear (green)
  • on the tracks to the turnouts: either clear or diverging (as sheldon said green over red)

a latching relay, such as in your link, has separate coils to switch and hold the contacts in one of two positions.

with a latching relay having the same coil voltage rating as the switch machines, the coils on the latching relays can also be connected to the Atlas turnout control (no diodes):

  • one set of contacts can switch between the red and green LED on the signals to the cross overs
  • the 2nd set could power the red LED (with the green always lit) on the signals to the turnouts.

if you don’t use a latching relay, you could use your mechanical method. But there are only two states for both your turnouts and signals.

10

If it was me, I would interlock the turnouts so that only one can be set to the diverging route at a time. Maybe you already have that, I did not analyze the circuit completely.

I don’t use twin coil switch machines, but Greg is correct, a latching relay on each could do this whole thing.

I would use Tortoise machines, three ice cube relays, and a single push button for each possible route. There are only three routes, only one can be clear at a time. On the prototype they would be interlocked only allowing one diverging route at a time.

Selecting either diverging route would return the other turnout to the main. Signal indications would be like you have them, but positioned as I suggested above.

Very simple…

Sheldon

11

Thanks for all the suggestions. It’s been a busy workweek, but hopefully I will find time this weekend to study the different ideas and see if I can simplify this.

I will definitely change to the latching relays.

And I will change the masts to more prototypical, as suggested.

The crossover and the turnouts are all so close to each other that I like to treat is as one section, meaning that once a train enters the first turnout, or the crossover, it is cleared to pass through the whole section, while other trains have to wait.

I don’t want a scenario where the train passes the crossover or turnout and then blocks it while stopping at the next one.

That’s one reason I have the turnouts interlocked in same position. When going straight on the mainline, both turnouts need to be off, but when taking the diverging route, the other turnout position doesn’t matter.

Yes, the momentary buttons are used to select a route, through the whole section, not specific turnouts. The diodes at the controls are so the buttons don’t interfere with each other.

I can see there being 3 signal aspects in a single turnout, but this is a double-turnout, with the crossover, so it gets more complicated.

But yeah, I could have made it more complicated than necessary, but since I haven’t installed yet, it’s not that hard to change things.

I have heard about Tortoise switches, but I am not sure I want the extra cost added right now, being on a tight budget.

12

shouldn’t block occupancy also be involved when determining signal indication?

when both turnouts are set to their diverging routes thru the crossover, i believe both routes should indicate clear. But when a train enters the blocks preceding the turnout or crossover, the opposite (actually both) signals should indicate stop.

13

Well yes, but that may be beyond his current goals.

Sheldon

14

understanding possibilities and trade-offs is always a good start.

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I do want to learn as I go. I might build a system that works in a certain fashion. But as I study and learn more, and getting input from you all, I don’t mind going back to change and improve things over time, striving to steer more toward prototypical.

By the way, my apologies for not being familiar with all the hobby terminology, and on top of that, English is not my first language, so sometimes I have difficulty explaining my thoughts clearly.