LEDs for Z-Scale Searchlight Signals

[Rivet Miscounter]

/tldr Q: What would be the best solution for the smallest-practical multi-color LED for Z-scale Searchlights?

I want to build some working searchlight signals in Z-scale, both singles and doubles, as follows:

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I have a good plan (I think) for the physical signal aside from the LED.   I'll describe that plan below since it is somewhat relevant, but the real problem is finding the smallest-practical multi-color LED so that is my question...what would be the best solution?  Notice I said practical...I'm definitely function-over-form here so 100% scale accuracy can give way to the practicality needs of a Z-scale model railroad implementation, but naturally I want to get that balance as close to scale as reasonably possible.  Another potential problem is stuffing wires, especially the double.

Plan is the following:
1. Use etched ladders and platforms from Micron-Art #1022 kits.   Wanted to use the targets, but the doubles are woven together so won't work for my situation.  The 3D-printed targets have better detail too, it seems.
2. NGineering.com .032" Thin-wall Stainless Tubing - https://www.ngineering.com/tubing.htm
3. Targets from Shapeways (or similar) https://www.shapeways.com/product/HC6GBKFP4/z-scale-searchlight-signal-36pc?optionId=64171118&li=user-wishlist

Found these as prospective LED sources but I think might be too large...still studying exactly how large.  They don't really look it in the coin comparison, but when Googling the package size it says 1/8" or 6mm respectively which doesn't seem right.
https://www.rr-cirkits.com/Notebook/Searchlight-led.html
https://www.showcaseminiatures.net/n_scale/n_scale_century_foundry_signals/LED0001.html
And a search a friend sent me that, after whittling down, still had 11 pages of results. https://www.mouser.com/Optoelectronics/LED-Lighting/LED-Emitters/Standard-LEDs-SMD/_/N-b1bb1?Keyword=rgb+led&FS=True  So maybe the answer lies in there somewhere.

And finally, Custom Signal Systems offers Z Searchlights at $30 and $50 respectively.   Not ruling these out, but I don't know much about them either so still investigating.
http://www.customsignalsystems.com/zscalesignals.htm

[Rivet Miscounter]

Here are a couple of relevant TRW posts, for your reading enjoyment. (full of defunct companies and 10-year-old solutions...which might still be relevant, mind you...just noting that is why I'm asking the question.)
https://www.therailwire.net/forum/index.php?topic=29917.msg324886#msg324886
https://www.therailwire.net/forum/index.php?topic=31256.msg394301#msg394301
https://www.therailwire.net/forum/index.php?topic=39727.0

[bdennis]

I have a few of the RR-Cirkits 3 colour LED's.
The picture in the link you provided is not the end product. They are smaller than that. See this picture.
You wont get anything smaller. The great thing is that they come pre wired with a decent amount of wire on them.

[Rivet Miscounter]

I have a few of the RR-Cirkits 3 colour LED's.
The picture in the link you provided is not the end product. They are smaller than that. See this picture.
You wont get anything smaller. The great thing is that they come pre wired with a decent amount of wire on them.

Hi Brendan, thank you for the reply.  I did see that photo and that's why I commented that they looked much smaller than the near-T-1 size that was suggested.    That's good to know that they are indeed smaller.  Seems like that might be the solution assuming I can squeeze two sets of wires down the ngnineering.com tubes for the double.

[bdennis]

Doug, No problem. The wires are very fine also.. Depending on the tube, you will probably be ok as the wire is thin'er than the normal enable coated amature wire that I have used in the past.

[Rivet Miscounter]

So, in the notebook section on the RR-Cirkits site it does reference the circuit board as being 3mm.     I did read this notebook entry but either missed or didn't remember that reference. 

Then, on the order form (which I had not looked at) it states: 1.3mm x 2mm 3 color LED 24" leads.

[bdennis]

Yep those are the ones.
Here is a close up next to an n scale microtrains coupler and spring.


and

[Rivet Miscounter]

So, just for argument's sake...   

What about something like this? https://www.mouser.com/ProductDetail/OSRAM-Opto-Semiconductors/LTRBR37G-4R4S-0125-0-2-R18?qs=PzGy0jfpSMv%252B%2FTjn17xfbA%3D%3D  (It's an 0404 RGB LED for those not interested enough to click but still curious.)

I'm assuming there has to be some type of additional circuitry to control the RGB, correct?  Or can an SE8C, for example--or possibly some other similar board--drive it natively somehow?

[bdennis]

Doug,
the above link is Red / Green / Blue. Not yellow.. So not ideal for a signal.
Plus the RR Cirkits one comes with the wires attached.. I would NOT like to try and solder wires to them (and I class my self as being very profficent with a soldering iron).

It looks to be the same size as the RR'Cirkits one.

The spec sheet seems to suggest that a mix of colours can achieve other colours, but I dont think the SE8C can drive it that way.
The SE8C can drive either 3 colour Common anode or Common cathode LED's as well as 3 pin / 2 colour LEDs and drive both the red and the green to get a yellow, and it can drive 2 pin bi colour LED's and ocolate the 2 pin 2 colour LED's to also make a yellow. I fine tuned mine with different size resistors on the red and the green to get a better yellow as the red is brighter than the green. (330 Ohm on the green and 680 ohm on the red. It is not a perfect yellow, but next to a red, you can tell it is yellow.

The RR Cirkits LED's wont have this issue as they have 3 dedicated LED's in Red, Yellow and Green. The Green is a more modern green that is heading towards blue.

I also use Team Digital SRC16 and RR Cirkits TC64 to drive my siganls. As My LED's are common anode and 3 pin 2 colour, I dont need the extra driver boards as they are set up to current sink, rather than current source. Thats why I use common anode LED's. If common cathode LED's are used, then the extra driver boards for the TC64 is needed.

Hope this helps.

[C855B]

[I am trying to find the thread documenting an N scale triple-head searchlight project with no success... still looking...]

Anyway...

Save time, money and follicles, and use the RR-CirKits LEDs. You will regret trying to wire 0404 RGB chips, and then there's the RGB mixing (i.e., "convergence") problem if you are in fact able to find a signal driver that understands RGB. Orangish-yellow/amber is really tough to reproduce with RGB without convergence, your eye wants to see the R and G elements if they're not fully blended. Fortunately, the chip you linked to has a 530nm G, "signal" green is 525nm; most RGB chips the G is yellowish, up around 560nm or so.

Here's the demo vid of the triple-head:

Not a valid vimeo URL
I think the mast is 0.032" SS tubing, from ngineering.com. It fit all 12 #36 wires. Barely. I had to be really, really careful to not scrape insulation in stuffing the wires. Sadly, it was less than successful in the long haul. I bumped it while cleaning track, shorting the R and G wires in the middle head. So it's back on the bench for rebuilding since repair isn't possible; stuffing the wires is a one-time operation.

Signal drivers are two TeamDigital SHD2 boards, now handled by RR-CirKits. Aspects are controlled by JMRI.

[bdennis]

Thanks for the info Mike.. Most helpful.

[Rivet Miscounter]

Thanks for the info Mike.. Most helpful.

Agreed, thanks @C855B for that info, and also thanks again Brendan @bdennis  for the followup.

Sorry to hear about the rebuild Mike, I'm sure that is beyond frustrating.   That signal looks amazing though...the payoff is worth your efforts for sure.   I only have to worry about doubles, thankfully...although I have a feeling that is going to be enough of a challenge for me.

[bdennis]

Mine have a total of 6 LED's




These are built with older 2mm 3 pin 2 colour LED's

[Wutter]

This is N scale, but I used a combination of 0402, 0603, 0404 and PLCC sized RYG LEDs. The real yellow makes a huge difference compared to the old method of mixing red and green on a bipolar LED.

I like the colors on the RR-CirKits RYG LED but my qualm is that their wire gauge is too big for the amount of current needed for the LED and makes it basically impossible to do a triple head in a scale sized, 0.8mm OD, 0.6mm ID mast (I use 40ga for triple head signals). Therefore I sourced my own custom 0404 RYG dies with the same colors and the correct 505-525nm green, if you're interested I still have a few of those RYG LEDs left over.

[Rivet Miscounter]

Wow @Wutter @bdennis now you guys are just showing off--and I love it!       Incredible work...thanks for sharing.

Alvin, thanks for the offer to sell the RYG LEDs but I'll defer to someone that might truly need that application...I think the RR-CirKits option should work fine for me.   I've pretty well documented the signals along the line I'm attempting to model and there are only singles and doubles unless I missed something.  (well, and some single/double 3-aspect Type-D's on the far end)