Model Train-related Notes Blog -- these are personal notes and musings on the subject of model train control, automation, electronics, or whatever I find interesting. I also have more posts in a blog dedicated to the maintenance of the Randall Museum Model Railroad.

2023-03-25 - Building LED Lighting

Category Train

Orion, Allen, and I had a discussion on how to refresh the building lighting on the layout.

For the record, the current lighting uses the traditional 12V light bulb system, controlled by a central massive power supply under the main yard, with rows of toggle switches mostly unused. Wiring is a mess. We don’t know which buildings are equipped with lights which are either not working or not connected.

I’ve made an attempt identify the power supply and what building were working here:
https://www.alfray.com/trains/randall/about.html#h.p043jf65vl34

One thought is that next time we dust the city, we should inventory which buildings are equipped with wires, and map existing through-holes in the support boards.

But going forward, how should we improve the lighting?

We could simply try to replace dead 12V light bulbs or add new ones.

Instead I’d suggest we go LED directly. For the Cracker-Jack sign, I tried to add a custom made LED, and it didn’t illuminate the building interior as I was hoping. My 5-mm style LED was just too directional for that.

And anyway, my philosophy with a place like Randall is to go with off-the-shelf commercial offerings. The goal is that long term maintenance should be as easy as picking up more of the same off-the-shelf commercial components and swap them or add new ones. The alternative is a custom DIY system, and these are harder to maintain when the original author is not around.

A good example of the issue with DIY systems is that 2-fire alarm building on fire on the layout. It’s been rock solid for so many years and that’s good because we have zero documentation on that thing. I have no idea how it was designed (Arduino maybe, or something more esoteric), access to the building is really hard, and I’m not going to touch it to figure anything out as long as it works. The day it stops working, it will be easier to just rebuild the electronics from scratch than figure how it was put together.

Thus although we could go the DIY route to add building LEDs, I suggest we use proper commercial components for that, especially now that there are some good choices on the market.

My proposal is to refresh the lighting by using the Woodland Scenics Just Plug Lighting System:

Pros of this System

I do like the philosophy of their system, and Woodland Scenics has just the right long-term reputation I need for that task. I also figure their system’s internals are likely very simple and potentially “hackable” if we need something custom, but we don’t need to go there.

I’d start exactly as they depict above -- with a starter kit and their little brick power supply. Once we’ve evaluated the starter kit, we would expand later if we were satisfied with it.

It also has the advantage of being able to spread the effort over time.

The specs of their little box is:

  • Each “light hub” has 4 output ports.
  • Each port can be either one LED or one “port sharing device” powering 4 LEDs.
  • Thus each hub can power up to 16 LEDs.
  • Each hub port is listed as being able to deliver 30 mA max, with its own dimmer.
  • Power can be up to 20V AC or 24V DC.

Under the layout, we have a 24V DC bus for the DCC relays, and a generic 12V AC bus for accessories. We would probably tap in the latter. The current building lights power supply delivers a nominal 15V DC, except it crumbles down to 9V DC under current load. If we remove the current suspicious load, we could use it as central power combined with the existing light switches.

Cons of this System

The main negative aspect of the Woodland Scenics Just Plug Lighting System is the cost of some of the components.

The prices are cheaper when looking at a reseller like ModelTrainStuff, but for cost analysis we’ll look at MSRP.

The “Light Hub” retails for $18, and can power anywhere from 4 LED directly up to 16 LEDs with the $10 “Port Sharing Device”:

  • Hub with 4 LEDs = $18/4 = $4.50 per output.
  • Hub with 4 Port Sharing Devices with 16 LEDs = ($18+4x$10)/16 = $3.63 per output.

Note that the above shows “price per output”, not per LED nor per port. More on this below.

The “power brick” is a basic 24V DC power supply delivering 1 Amp max. At $25 the brick, it’s a bit on the high side. The hub specs indicate 30 mA per port, which means in theory one brick is good for ~30 ports, which explains why it makes sense to use the “Expansion Hub” ($17) to power multiple hubs with one power supply brick.

In any case, the power supply brick is one place where one can instantly save by omitting it as it’s not a necessary component -- any existing 12V-24V DC auxiliary power bus will do, with the proper cable adapter. The power supply brick is a mere convenience, and it's a one-ticket item, thus somewhat justifying its price.

Now we get to the important part, the LEDs. The starter kit only comes with 2 LEDs, for a 4-port device, which is a bit odd. So upfront we’ll need more LEDs. These are sold in pairs, and at $9 the pair seems like something quite expensive for a simple LED, a tiny cable, and a JST modular connector. The whole thing assembled can’t cost more than a quarter dollar in parts per thousand, so again we’re paying for convenience here (and by that I mean everything from design, to production, to marketing, up to distribution, and every entity adding their own profit margin).

So that’s the part where one could save by going DIY -- buy a bag of similar JST modular connectors, buy a bag of LEDs, and solder and wire the things yourself. That is trading upfront costs for skills, time, and inconvenience. That’s why I had this discussion above comparing off-the-shelf vs DIY. I’m planning 10-years ahead -- what happens when one LED fails in 10 years from now and someone else is dealing with the maintenance? (That’s basically my problem right now!) I could leave a note today telling that person “get part JP5742 from Woodland Scenics, plug it here, and you’re done”, or I can leave them in the dark (literally), expect them to collect the DIY parts (which ones?), and hope they have basic knowledge to do some soldering, and reinstall the new LED in place. So that’s what I mean by the cost of convenience. We’ll buy these 2 LEDs for $9 now, and heck we’ll even buy a couple spares such that my counterpart in 10 years can find them and have a model to look at without crawling under the layout first.

So now, we can recompute the cost of the system by mixing the “per-port” cost of the hubs with the per-LED costs:

  • Hub with 4 LEDs = $18 hub + 4 LEDs for 2x$9 = $9 per LED installed.
  • Hub with 4 Port Sharing Devices with 16 LEDs = ($18 hub + 4x$10 + 8x$9 leds)/16 = $8.125 per LED installed.

So that's what I was saying: not cheap! And to be clear, I'm fine with that as long as the product justifies the cost (all reviews I have seen so far seem to agree on that part).

Possible Implementation / Installation

To tackle a project like this, it’s nice to start with the end-goal and then split it into milestones. I envision something along the lines of:

  • Main focus is lighting buildings in the Stockton town, starting wit the main station.
  • Secondary focus is the central part of the Fairfield Industrial town.
  • The main station building could easily use 2 or 3 LEDs.
  • Most buildings would probably only use a single LED, some may need one per floor/room for variety.
  • Thus one light hub would easily cover anywhere from 4 up to 10-ish buildings with the use of their “port sharing device”.
  • 2 light hubs should cover the Stocktown town.
  • 1 light hub should cover the Fairfield Industrial town.
  • 1 light hub should cover the Lodi town in a future expansion.
  • As there is enough distance between all these hubs, I do not think we need the “expansion hub”. We can just power them individually.

In any case, we would start with the “Starter Kit”, compare their power pack to using the 12V AC system from the layout, or from the current building lighting supply. We would also evaluate how their LEDs illuminate a building.

Our main focus is the Stockton station, however I’d use the Fairfield Industrial buildings as the “canary” to experiment with that starter kit, and only tackle the more complex station once we know the limitations of the system. Then after the station, we can expand to the rest of the Stocktown town.


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