LED routes and simplified signal bridge

Model Railroader Electronics and DCC
1

I have a (hopefully) simple problem my limited electrical knowledge can’t crack. I have a 5-track section (see diagram below) where I want to have a very simple “signal bridge” spanning the tracks indicating which route is chosen. The signal bridge will have a simple 2-pin bicolor red/green LEDs. Green will indicate the active route. Far from prototypical but helps me and my grandson keep trains on tracks and off the floor.

Turnouts are controlled via DCC (Digitrax DS 64s/JMRI), and all I’m trying to do is use the Tortoise’s aux contacts to control leds to indicate the chosen route. Aux contacts for these 4 tortoi will have a dedicated 12v power supply.

Ben Lake had a simple solution in a recent Canadian Canyons video, but that just turns a green led on or off. I’d prefer to have red on the 4 inactive routes and green on the active route. I have plenty of bicolor red/green leds and resistors on hand, but if I need to buy 3-pin leds or some sort of board to make this happen, that not a problem.

https://www.flickr.com/photos/131230956@N05/37376232115/in/dateposted-public/

Any help greatly appreciated.

2

Can’t answer your question, but I can tell you how to post a pic. Bottom right corner to the right of the star is an arrow, click on it and copy the BB code. BB stands for bulletin board.

Paste it directly in your post, do not use the picture icon, do not mess with the sizing

Route diagram

3

Thanks, I thought I followed the " how to post a pic" instructions and then thought " oh, crap now everybody has to click a link." My apologies.

4

Do you have both sets of contacts available on the Tortoises, or are you using one set for forg power and the other to control your lights?

Either way this is doable as a simple switch matrix.

This is strictly an electrical problem, not electronics. I’ll assume 1 contact set on the Torts, keeping the second free for frog power. This will be easier with 3 lead bi-color LEDs. If they are common cathode (most common type), the common lead is the -, put the resistor for each one on that lead and connect to the - of your power supply. You’ll also need some regular diodes, 1N914 or 1N4148 types are fine.

I think I have this workedout but I need to draw up the schematic in KiCad or something, if I scanned this piece of paper I drew it on, no one would be able to figure out it. Plus tthere’s still one part for track 4 and 5 that isn’t quite right.

Basically you are looking at a diode matrix - instead of the switches you have your tortoise contacts. Instead of the switch machines, you have the LEDs. Chart it out. For example, when Switch A is normal, you want 3 Red, 4 Red, and 5 Red, with 1 and 2 determined by the position of Switch B. When B is normal, you want 2 Green and 1 Red. When B is reverse, you want 1 Green and 2 Red.

When A is reverse, you want 1 Red and 2 Red, 3, 4, and 5 are determine by Switch C and D. When C is normal, you want 3 Green, 4 Red and 5 Red. When C is reverse, you want 3 Red and 4 and 5 controlled by D.

If D is normal, then you want 5 Green and 4 Red. When D is reversed, you want 4 Green and 5 Red.

Now if you just connect all this together you will see there are sneak paths where both the red and green will be on in a given LED. These are places you need to insert diodes so the power only flows one way and can’t backfeed another LED.

5

Randy, there’s no frog power. And I really appreciate the description of what I need to do but this one just won’t translate to my feeble brain without visual—I’m good at many things, electronics is not one of them. Sorry I forgot to mention turnouts are basic Atlas code 83, no power routing. Both contacts are available on the Tortoi. Draw me something and I will design a logo pro bono for one of your industries or Lines. I finally figured out how to work Bill Bruford into an industry without being too terribly cheesy: Bruford Drum Brakes: Best power, control and finesse. (And dang if that isn’t true,!) I will post my logo for that one tomorrow.

6

Wonder if he’s related the the attorney over at Anderson, Bruford, Wakeman & Howe.

BTW I’ve finally gotten to meet all of them except Bill and Chris (RIP). Actually Alan was out recovering froom back surgery that night as well. Just saw them again recently and I dooon’t know how he does it, clearly his back is still trouble based on how he seemed barely able to walk out froom behind the drums to take a bow - and basically couldn’t bow, either. But his playing was spot on. Next week it’s Jon, Rick, and Trevor again.

OK, since I can use both switches in each Tortoise - this may make it easier, I’ll redraw it. I still need to do it in some electronic form, my scribbles on paper are not easily followed.

–Randy

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Alan is great, solid as a rock. Had tickets to see them last Monday, they had to cancel at last minute when they learned Steve’s son had passed away. Bummer. Here’s my logo, gonna turn a Walthers Brookhill Farms Dairy into a small automotive parts manufacturer.

Bruford Drum Brakes-01 by John Holland, on Flickr

8

I’ll get something drawn up. That looks good. Just be sure to put a guy standing around near it with a t-shirt on that says No!

Yeah I saw that show a while ago in Hershey - could have left off Rundgren, but Carl Palmer was also amazing. Yes worked out well with Dylan Howe and Alan, especially as they tended to set it up such that Dylan, who as prmarily a jazz drummer even cites Bruford as a big influence (no kidding, right?) playing on the older Bruford-era songs and Alan on his stuff. Second time I’ve seen them with Billy SHerwood now, I can see why Chris hand picked him to step in. Then the ARW group - I saw them early on their tour, and I was right in front (2nd row) and it was the most fantastic concert experience of my life. So when they announced they were playing right in Reading and on my birthday - of course I have to go again!

Hmm, another way to do the signals would be to just use green LEDs, and only light the selected route - like approach lit signals. Only the one that the train is coming in on will lght up, the rest would be dark. But the others all red is doable.

(have to add some train stuff, no one knows what we’re talking about otherwise)

–Randy

9

The only real advantage of having the reds in addition to the greens is a clearer indication of which track is selected from across the room, in low light, or from an angle. But I’m starting to wonder if it’s worth the extra wiring hassle. I’m not using any control panels on the fascia–did that on first layout and hated the look of it. Ultimately I will have virtual control panels on tablet(s) via JMRI, but might be awhile before I get there. In the meantime I’m using the Digitrax throttle, and its easy enough to set the route, but some of those buttons are too sensitive. Tapping 5 often results in 55, etc. If I’m not paying close enough attention, it might not do what I thought it did. Hence the desire for a nearly foolproof indication over the tracks themselves.

10

It’s doable. The biggest complication is that B turnout on the straight route of A. The rest down a ladder are pretty easy. I still think the 3 wire bicolor LEDs will be easier, I was trying to work it out with the 2 wire type, since it’s pretty easy to switch colors - you use TWO 12 volt power supplies, hook the + of one and the - of the other together as the common - that gets a resistor and goes to one side of the LED. If you touch the free + power supply lead to the other side of the LED< it will be red or green. If you hook the free - line from the other power supply to the free LED lead, it will be the opposite. Easy enough for a single LED - the _ and - from the power supply go to the switch terminals of one of the tortoise contacts, and the center contact goes tot he LED. Tortoise moves one way, red light. Other way, green light. The problem is the blocking diodes. Since the wire that needs to have the blocking diode added can be either + or -, the diode will oonly block for one condition, in the other it will let the current pass, causing either a light you don’t want to light up to light, or else a dead short.

I have not yet given up on the simple way. I have another idea that needs a more complicated circuit but is easier to hook up, just ries to the Tortoise pins and wires tot he LEDs, and the correct LEDs will light for each condition. You don’t need to understand what goes on in the circuit, just that Toroise A connects here, and LED 4 goes there. I’ll draw both ways.

–Randy

11

Yes, well here is ppicture of my first layout. I made the signal bridge by bending 1/16th inch welding rod. Bridge was ground, LEDs were the sighals.These were bi-color LEDs. + = RED; - = Green.

Fifteen lamps. Each LED had one DPST relay. No current = red, power = green.

It is normal for signals in this sort of plant to be RED until the toweroperator alighs the plant and clears the singnals. In this instance, the bottom signal indicated which track was clear to move and the next two signals indicated the route.

So the LOGIC for the signals had to come from the Tortoise contacts and or additional relays.

So there was a realy for each lamp, and another 4PDT relay for each switch lever. From the terminals on the big relays the logic to the lamp realys was determined. Remember 0 voltage = a red light, so all that these switch relays had to do was pass a positive signal to the appropriate lam relays.

ROAR

12

OK, so I’ve finished binge watching Game of Thrones, given up on Vikings (football), and spent some time looking into truth tables and circuits. Conclusions:

Wow, I am clueless. As in reverse-smart with circuits. The more I dig, the more bewildered I become.

Lion: I’m not ready to try brass, stuck with plastic for now. Circuit explanations are waaaaay over my head. But I love looking at your Old Skool automation. I should drive out there sometime, I’m about 300 miles straight east of the Abbey.

Randy: I’ve taken your suggestions and tried to convert a truth table to a circuit, but just cant make the leap.Theres some articles about doing a similar circuit with the motor contacts and rotary switches to control the physical route, but… again, can’t make the leap. Mind if I PM ya later this weekend on this one?

13

In your OP you seem to indicate that you’d be willing to spend a few bucks in order to have a simple solution. If that’s the case, you could install another DS64 and connect your LED’s as if they are a Tortoise. Add the LED’s to the route table you are using to select the track. Wire the LED’s so that when they are “closed” they will be red, when “thown” they will be green.

14

I’ve actually got it figured out with just the Tortoise contacts, the problem is making a READABLE drawing of it. My hand scribbles will not be understandable by anyone. What I need to do is make a schamtic symbol for a Tortoise in KiCad, then I can electronically draw it all out so it will be neat and possible to follow. I keep trying to be neat and after I get about 2 Tortoises in it starts to resemble a mess of lines that I’m sure will only confuse rather than help.

–Randy