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Discussions keep coming up about a signal control board, especially now that there seems to be several choices for cheap O-gauge track signals.

That being the case, I figured we'd start a new thread and see what features might be desirable in something that would be in kit form for users to build.  I'm thinking we'd sort out a feature list and then whittle it down so that it could be made in an inexpensive manner with common parts.  I'll start with a few attributes and we'll go from there.

  • Low cost! (one of the primary objectives)
  • Stand alone, doesn't need any ITAD or other sensing device.
  • Multiple types of input, i.e. IR, insulated rail, etc.
  • Drives two and three aspect signals with appropriate delays for yellow & green (programmable?)
  • Drives road crossing crossbuck signals directly.
  • Direct drive of LED or incandescent lamps.

I'm thinking a thru-hole PCB design with a inexpensive parts BOM that can be easily assembled by most folks that can solder.  Having a board greatly simplifies the task of assembling one or a number of these.

Let's all join in and toss some ideas around!  

Last edited by gunrunnerjohn
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I am (was) a big fan of the Atlas signal system. I believe it had the features you list and also the ability to link the signals together to operate from multiple block inputs. I kind of gave up on them since they have not been available for a while now, but I have heard rumblings that Atlas may be remaking, redesigning, remanufacturing them or something along those lines. The big problem for me with the Atlas signal system was cost, not that it wasn't worth it, just that is was a bit above my price range. But, it really is/was a neat system.

Maybe I can find a feature list from the Atlas signals, like from a listing or catalog I might have around here somewhere? It's will probably be cost prohibitive to do all the features that system had, but I guess you never know? 

Another idea (probably not a good one) would be to maybe have one PCB with different schematics of designs from 'basic' to 'full featured'? Tthe user could then select how far they wanted to take things and how much they wanted to spend? I'm dreaming here, I think...

Also, I have no ideas about any circuits that would be needed here, but I do realize, to quote GRJ, "Nothing is so easy as the job you imagine someone else doing" which is probably what I am doing here.  

Edit: The post below by The Dude about daisy chaining the signals is one neat feature of the Atlas system. 

Last edited by rtr12

Remember, the #1 goal was not expensive!   I'm afraid if we get into daisy chaining signals and all the complexity that involves, we'll defeat the whole purpose of the project.  It this whole project ends up costing more than around $10 total for a board, I'm afraid it's not going to go very far.

After all, Azatrax has one that does all this and also handles signals in two directions for $40 for each board.

linked block signals, single track

gunrunnerjohn posted:

Discussions keep coming up about a signal control board, especially now that there seems to be several choices for cheap O-gauge track signals.

That being the case, I figured we'd start a new thread and see what features might be desirable in something that would be in kit form for users to build.  I'm thinking we'd sort out a feature list and then whittle it down so that it could be made in an inexpensive manner with common parts.  I'll start with a few attributes and we'll go from there.I'm thinking a thru-hole PCB design with a inexpensive parts BOM that can be easily assembled by most folks that can solder.  Having a board greatly simplifies the task of assembling one or a number of these.

Let's all join in and toss some ideas around!  

I have an Arduino Nano configured to do some of this.  I use it with the WeHonest 2 and 3 aspect signals.  It is sensitive enough to detect your fingers touching the ground and signal rails. (I have it currently set for 3 rail operation. 2 Rail would need to be converted for current sensing instead of ground sensing.)

  • Low cost! (one of the primary objectives)

  About $3 for the Arduino, and $1.50 for the breakout board it plugs into to have a screw terminal on each pin. So $4.50, and each one controls two signals.

  • Multiple types of input, i.e. IR, insulated rail, etc.

I use it with insulated rail. I do use IR detectors with the nano for switch anti-derail. It would be pretty easy to add software to detect either ins rail or IR, and use a toggle switch on one of the digital pins to flip which one is being utilized.

  • Drives two and three aspect signals with appropriate delays for yellow & green (programmable?)

I do a PWM fade-out/fade-in.  The WeHonest signals have a single resistor connected common anode, so you cant have the multiple led's lit at the same time.  But the fade-out/fade-in under software control looks pretty good.  (It looks hideous on a video at 30 frames per second due to the strobing effect.)

  • Drives road crossing crossbuck signals directly.

It could drive a servo-driven crossing gate or wigwag directly without any issue. It would need an fet driver if the mechanism used anything that drew more current , like electromagnets,  or if we wanted it to drive the sound. 

  • Direct drive of LED or incandescent lamps.

Led's are direct drive.  Incadescents would need to have logic level fets on the output pins.

 So, you could basically take this setup, add a few fet's for higher current draw items like incadescents, and be pretty close. 

One nice thing about the arduino microcontroller is its ability to add pullup resistors under software control, without the need for discreet components.  That really comes in handy for ground sensing devices.

For my future large layout, I plan on some Arduino Nano's simply becoming block detectors (8 blocks detected per Nano) with these block detecting Nano's communicating to an ethernet nano which sends the block data back to a main system, which then can software control the aspect signals from that data. This would allow easier wiring of the signals, as I wouldnt need to wire the blocks to each signal. 

 

It's obvious that you would want to include signal aspects for CLEAR, APPROACH, and STOP. But I would suggest, since we're already talking about grade crossing flashers, that this device be able to represent aspects that include flashing as well.

Flashing GREEN for LIMITED CLEAR or whatever you want to call it. Flashing YELLOW for MEDIUM APPROACH as was used by Southern Pacific. And Flashing RED could be a RESTRICTING aspect. Your railroad may use different terminology for the various aspects.

Another thought is a signal that acts as a Control Point (CP) at the start of a siding. In that case, you would want to have a 3 aspect signal head over a 2 aspect head indicating a straight or diverging route for the switch into the siding. Probably GREEN for straight and RED for the siding.

I agree that you want to keep the Signal Controller separate from Block Detection and Switch Orientation devices. For the Signal Controller, it all boils down to inputs driving the signal aspects.

I like the activation that is done on some boards that I purchased using photo transitors. S gauge using two rails is not conducive to the insulated rail. The possibility to use it with the block signal and a timer chip for two or three light signals or maybe to input to a relay to operate a semaphore. The photo transitors are quite easily hidden between the rails.

Ray

I had considered using the Arduino Nano as a base for the control function.  It has lots of I/O pins and is dirt cheap. The external circuits would be for input and output signal conditioning and of course a generic source of power.  While you could consider a DC power brick for the power, I think having a bunch of little bricks, one for each unit, may be a bit cumbersome, so I was thinking along the lines of an AC power supply that will work from track power or accessory power from around 12 VAC to 22 VAC.

Some of this is getting a little "over the top" for a cheap signal.  Also, all of those intricate signalling variations have to be accommodated by the logic.  If this starts out so complex that it's a six month development project, it's probably dead already.   Also, if we start with the hardware base to support some of this stuff, the software can be customized in the future to expand the capability of the signal board.

CGWforever posted:

What about two light block signals? I see this show three lights.

You simply don't connect to one of the outputs.  Connect to the red and green only, presto, you have a 2-light signal.

I was planning on doing a full signal system on my layout, but I was unable to get all the equipment I needed to get. Since Custom Signals is pretty much no longer selling anything it seems like.

One thing I think would be useful to have is one that can some how see what direction a switch is thrown and have it reflected on the signals somehow. That may end up adding more complexity than you want to the board.

All  the other aspects listed seem interesting.

My idea is to start out small with the possibility of expansion to handle more features.  As far as actually sensing where a switch is, it depends on the switch.  However, that's mostly a mechanical issue of actually sensing the switch position, and it's not always that easy.

My solution would be to use either Tortoise switch motors with the position contacts or Fastrack that has position sensing.

Alex (Ingeniero No1) was working a whole system that did very sophisticated switch position sensing, and was sensitive enough to catch partially thrown switches, don't know what happened to that project.  I know he showed prototypes, and it looked very promising.

Gunrunnerjohn.....thank you!! Cost is the first consideration followed by simplicity in application. My only suggestion would be to offer simple wiring guides for signals from Lionel and MTH......I am not discounting the Atlas products but cost and availability fly in the face of what you are proposing. I also recognize that there are other companies which offer signals, even some "boutique" companies which offer very detailed handcrafted signals but accounting for all variations again might detract from the primary objective.

Well, I'd leave the wiring guides to folks that actually have the signals.  Since right now this is envisioned as a community project, I'm not going to spend a ton of money to buy every signal possible to document them.

Truthfully, this all grew out of the desire to have inexpensive signals, and in the other signal thread, we were discussing stuff like the WeHonest Signals, they have some decent looking signals for around $4/ea.  The point was made that the control boards for these signals exceed the signal price by multiples, so the idea of an inexpensive board was born.

gunrunnerjohn posted:

As far as actually sensing where a switch is, it depends on the switch.  However, that's mostly a mechanical issue of actually sensing the switch position, and it's not always that easy.

My solution would be to use either Tortoise switch motors with the position contacts or Fastrack that has position sensing.

All I have is Atlas Switches on my layout. So I see if I can figure something out.

Like I said it may add more complexity than wanted right know. Which is way I said all the other features looked like I could use them.. Depending on how they would be implemented.  

tcochran posted:
gunrunnerjohn posted:

As far as actually sensing where a switch is, it depends on the switch.  However, that's mostly a mechanical issue of actually sensing the switch position, and it's not always that easy.

My solution would be to use either Tortoise switch motors with the position contacts or Fastrack that has position sensing.

All I have is Atlas Switches on my layout. So I see if I can figure something out.

Like I said it may add more complexity than wanted right know. Which is way I said all the other features looked like I could use them.. Depending on how they would be implemented.  

For Atlas switches, you can either use the Atlas under-the-table switch machine (which has contacts for indicating switch position) or the Atlas snap switch relay with the above-table switch machine to indicate switch position. That's how the Custom Signals boards handled it with Atlas switches.

 

 

  Could someone explain why and how crossbuck lights & bars (not track signals) could benefit from a directional detection. I can only seem to focus on the fact that if the space between A&B is occupied, both crossbuck signals should activate. Speed doesn't even really matter; on slow days you wait longer to cross. That is what I've observed on the real rails. I even knew the exact A&B spots for crossings near me; fast or slow they triggered the crossbucks at the same spot every day.

Adriatic posted:

  Could someone explain why and how crossbuck lights & bars (not track signals) could benefit from a directional detection. I can only seem to focus on the fact that if the space between A&B is occupied, both crossbuck signals should activate. Speed doesn't even really matter; on slow days you wait longer to cross. That is what I've observed on the real rails. I even knew the exact A&B spots for crossings near me; fast or slow they triggered the crossbucks at the same spot every day.

The crossbuck signals should activate while the approaching train is some distance from them, but they should stop as soon as the train has cleared the crossing.  The fact that the distances from the crossing for activation vs. stopping are different means that directional detection is needed for this feature.

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