How to repeat PL's on the facia without breaking the bank

[daniel_leavitt2000]

1. I really like this idea because it is so PRR. Any modeler looking at the layout will instantly know it is PRR without even seeing motive power. This adds tons of atmosphere.

2. I am assuming you want the traditional look of the cab signal box, correct? I see what Pete was saying about using just two small signal heads with mini LEDs. You would be able to shrink the signal size by 3/5ths, but it would look more like conventional PRR signals rather than a cab signal.

3. Is there any reason why you need to space the tracks so close together on the control panel? Why not go nuts and make the whole front façade a near full size control panel? That would take care of any space issues.

4. Slightly off topic... anyone have any interior photos of Conrail cab signals?

[eric220]

1. I really like this idea because it is so PRR. Any modeler looking at the layout will instantly know it is PRR without even seeing motive power. This adds tons of atmosphere.

Thank you!

2. I am assuming you want the traditional look of the cab signal box, correct? I see what Pete was saying about using just two small signal heads with mini LEDs. You would be able to shrink the signal size by 3/5ths, but it would look more like conventional PRR signals rather than a cab signal.

I've thought about rebuilding the cab signal with 3mm LEDs, but the aspects are pretty dang microscopic as it is.  If I go that route, I'm pretty well resigning myself to the fact that the aspects are actually being read based on which LED is lit, and not what's on the lens in front of the lamp.

3. Is there any reason why you need to space the tracks so close together on the control panel? Why not go nuts and make the whole front façade a near full size control panel? That would take care of any space issues.

  Such ideas you give me!  I'm having fun just imagining the issues with translating the full track diagram on to a surface that twists, turns, and flows in three dimensions.  In the end, probably impractical, but interesting none the less.

4. Slightly off topic... anyone have any interior photos of Conrail cab signals?

Dang... We made it onto the fourth page before someone tried to turn this into a Conrail discussion.  Must be a record.   

[eric220]

On the other hand... If I were to use 3mm LEDs (and I'm kicking myself now for not following my instinct and making both a 5mm and 3mm version at the same time) that reduces the overall height to 1", same as the PL's I made.  That means I can do this:



5"x8"... Not bad for a four track universal crossover control panel.

Edit: Points for anyone who can tell me where the trains are and which routs are set.  Track 1 is at the top, 4 at the bottom.

[Kisatchie]

1. I really like this idea because it is so PRR. Any modeler looking at the layout will instantly know it is PRR without even seeing motive power. This adds tons of atmosphere.

Hmm... Kiz wouldn't know
anything was PRR if it bit
him on the a-a-a-a-ankle...

[TiVoPrince]

Looking
so exquisitely cool.  While I only marginally understand PL signals although I probably could be educated.  It seems that colour could be as simple as attacking the 'lens' with a marker to test your options.  Build with white LEDs and you could easily test both theories...

[eric220]

And you thought this thread was dead...

I took my ingenious little device around and showed it to several other railroaders, including some of my Gandy Dancers, Ed K, and Dave Foxx.  The overall appraisal seems to be that it's very cool (please forgive the immodesty).  Even so, as I previously mentioned, I wanted to try a 3mm version, and while I was creating new 3D models, it only seemed fair to give Peteski's suggestion a try.  Hence:



Which became:



As you can see, my PL design exceeded the resolution of my friend's 3D printer.  A quick revision later:



First came the 3mm version of my already built 5mm cab signal style repeater.



I've pretty much decided that this is impractical.  I had high hopes for it, as its size is much more conducive to facia control panels than the 5mm version, but some quick legibility tests proved disappointing.  The 5mm version is clearly legible from about 6 feet.  The 3mm version is only legible from about 3 feet.

This brings us to the 3-way test.



Novelty aside, I'd say there's a pretty clear winner here.  The PL version is clearly legible from across the room.  There are still some pros and cons of the PL design to consider.

Pros:
-Legibility
-No 3D printed elements visible on the surface
-Legibility
-Only one part plus electronics
-Legibility
-Size.  It's almost identical in height to the 3mm cab signal version, although fatter.
-Legibility
-It can be manufactured in a fraction of the time of the cab signal style repeater.
-Um... Legibility... By an expletive longshot

Cons:
-Cost.  With the cab signal version, I can probably do the whole layout for under $100.  The PL version will cost several hundred dollars.
-Assembly is far more complex and time consuming (not all of the gandy dancers are electronically inclined).
-Implementation issues.  The proof of concept... proves the concept.  Still, there are some practical issues to overcome before production.
-It's not as novel as the cab signal style.
-It's much more prone to assembly errors.

More pondering on the subject is clearly called for...

[VonRyan]

I like the cab signal idea. The 3mm ones are good as long as your operators are dutifully following their trains, but the 5mm removes any possible doubt about the aspects.

It also gives the operator more of a real-railroading feel since it would be something that was in the cab of a locomotive.

[reinhardtjh]

Cons:
-Cost.  With the cab signal version, I can probably do the whole layout for under $100.  The PL version will cost several hundred dollars.

Is the cost in the electronics or the PL holder for the LEDs?  Were you considering using RP for all the PL LED holders?  If so, couldn't you make a few as masters and then make RTV molds and cast them from black urethane?

[eric220]

The 3mm version is only good if you're standing right in front of it.  If you're at an angle, or more than a few feet away, you're relying solely on which lamp is lit, rather than the aspect.  I can probably edit the 3D file to make it clearer, but even so, the aspects are so small that they're almost illegible, even within a few feet.

[eric220]

Is the cost in the electronics or the PL holder for the LEDs?  Were you considering using RP for all the PL LED holders?  If so, couldn't you make a few as masters and then make RTV molds and cast them from black urethane?

The cost is in the sheer quantity of LED's, other components, and the need for a custom printed circuit board to reduce the complexity of assembly.  The cost to build the brackets is higher than the cab signals, but not unreasonably so.

[Philip H]

So I've largely stayed out of this fray since 1) I'm not a SPF and so have ZERO background with the prototype or its practical use; 2) my little switching layout MAY have a total of 6 signal masts on it - if I do so that will be more about enhancing the "cool factor" then replicating actual signal practices; 3) inspite of having a ton of training is using all sorts of electronic gadgets and gizmos, the intricacies of design elude me.

That said, I think you are really facing a choice between cab repeater in 5MM and the PL. FWIW, as a nearsighted person, bigger clearer signals are always better, so for that reason I'd say splurge on the PLs.  But either way, I'd recommend putting a Cheat Sheet of each signal (or combination) permanently on the clipboards your operators will be working with, so newbies (and non-SPFs) can easily cross reference your solution to what they are supposed to do.

[eric220]

That's pretty much where I am: 5mm cab signals or PL's. I'm torn. The full PLs are more legible, but I wonder if clusters of them are going to be too distracting. I think I'm going to have to do some more complete mockups and some user testing.

I'm actually surprised that I proved one of my initial assumptions wrong. Namely that I can, in fact, make PLs that are more compact than the cab signals.

[VonRyan]

That's pretty much where I am: 5mm cab signals or PL's. I'm torn. The full PLs are more legible, but I wonder if clusters of them are going to be too distracting. I think I'm going to have to do some more complete mockups and some user testing.

I'm actually surprised that I proved one of my initial assumptions wrong. Namely that I can, in fact, make PLs that are more compact than the cab signals.

Go with the cab signals.

If you are worried about cramping your fascia, just make the cab signals into plug-in so star you only need 6-pin sockets on the fascia and the operator has to move his cab signal as he crosses into each new signaling block.

[eric220]

Resurrecting this thread from the abyss, I present this:



This is a sandwich comprised of a 1/4" piece of black acrylic laser cut and laced with LED's thusly:



The LED's were then connected to a pair of RRCir-Kits control boards and hooked into the railroad.  This was then layered on top, printed on plain white printer paper:



On top of that went this, printed on transparency film:



As is plainly visible, this is still in the experimental stage.  This is actually phase 2, with emphasis on experimenting with different levels of grey on the cab signals.  You may have noticed that the PL's are dark.  That seems to be a limitation of the RRCir-Kits system.  The control boards are only putting out about 1.5 volts (not sure how many amps) across the LED's, and that's evidently not enough to drive both the PL's and the cab signals.  This raises a significant concern regarding the final implementation.  This system may not have enough power to drive the layout signals plus PL repeaters.  (There's actually some question at this point as to whether it can drive the layout signals plus one additional LED.)  You also may have noticed that the lower arms are brighter than the upper arms.  That is due to the addition of a 100 ohm resistor to override the built-in resistor on the control board.  I was hoping that adding them would increase the current enough to drive both sets of LEDs, but no such luck.

The revised cab signals are actually surprisingly visible.  I can read the aspects clearly from 6+ feet.

[mmagliaro]

Here come the Electrical Engineering Police, ha ha!   

Serious... I will try to offer some help here.

First, circuits do not "put out amps".  They have a current limit or capacity, and current will flow based on
the load resistance.   Now that I've gotten that off my chest....

Now... lots of questions...

You say that there is 1.5 volts on the output terminals to the LEDs.
That should be sufficient.  The problem then is that the outputs are limiting the current so that perhaps there isn't
enough to drive multiple LEDs.     Did you try just using clip leads to connect one LED and then another across one of the outputs?
What happens?  When you have one in there, and it is lit, and you put another LED across the same outputs, do
they both go out?

You say you added a 100 ohm resistor to "override" the built-in resistor.  How exactly did you do this?  Did you
wire it across the built-in resistor, in parallel, or did you truly disconnect the built-in resistor and bypass it? 
What value is the built-in resistor?   
If the outputs are 1.5v, then a 100 ohm resistor will limit you to 15 ma of current.  That's a little on the low side.
I would try to get 20-25ma to get good brightness from two LEDs, so a 68 ohm might be better.  But again,
this is only if your 68 ohm resistor is the only one in the circuit.  If it is in parallel with some other existing resistor,
we really need to know what that other one is.

This has to be fixable.  I can't believe the outputs on that thing can't support 2 LEDs.