Define high and low lumens

Dawn and dusk effects aren't

Dawn and dusk effects aren't the whole sky, they're a limited region when the sun actually rises and sets. If you want to duplicate those effects, then you need small areas on opposite sides of the room (east and west) and  use your colored lights in those spots. concentrating on reds, purples and blues. I've not seen RGB strands that will mix those colors effectively like you would need for a sunrise or sunset... you might have to use multiple strands, and fade in the red, blue, and purple from 3 different strands to make it work

This is one of those applications where incandesents still might be superior. I'm thinking colored spots hidden behind the horizon scenery, thrown up on the backdrop.

Thanks, Joe

At better than 500 lumens per foot that would definately be high. I think part of my problem is that I work for an electrical consulting firm and I'm used to specifying high end LED fixtures. When I see LED tape on line a 140 lm/foot I realize that's not going to cut it.

I would really like a good solution that is high lumen but RGBW. The eBay LED RGBW don't have enough punch to do the ambient white because there are fewer white SMDs.

I probably should be thinking of doing the white separate from the color with something that is 0-10V dimming and can be controlled by an Arduino. Then I'm thinking of having perhaps three zones of RGB that can be independently controlled (dimming and color shift) by another Arduino. In this way, I can have JMRI signal the time of day on the fast clock to the Arduinos which are programmed to slowly shift through dimming and color change in the room to my taste based on the time. If you paused the fast clock on on of my control tablets, it could restore the room lighting to full daylight setting.

There's also distance from the lights to the surface

Keep in mind my lights were 11-13" above the track level in most locations using a shadowbox design.

The distance from the lighting to the track level makes a big difference. I think what you need to consider is the LUX value, which includes the effect of distance from the lighting to the surface being illuminated.

My Lux value is ~900 for 310 lumens at 13" away. By comparison, 100 watts (1600 lumens) at 48" away (in the ceiling) is only 342 lux. So my 20 watts (310 lumens) every two feet at 13" away has almost 3x the lux. Given my lighting would be equivalent to almost 300 watts from the ceiling, I find my 310 lumens to be plenty bright.

So what kind of lux value are you looking for? You can use this lumens-to-lux calculator:

http://www.dmslighting.com/tools/illuminationconverter.html

I just use 120 degrees as the view angle and then use the lumens to lux calculation.

Correct

Lighting levels need to be calculated at the target surface. My lighting now is good and I'm using LED par lamps developing about 700 lumens which are on 3 foot centers 48" above the benchwork. I suppose I could get a light meter and check what the current levels are. The problem with the current lighting is it is line voltage dimming and only dims to about 10%. I would like to replace it with something that dims better and uses a digital signal so I can control it more easily.

LED lighting is still advancing so quickly that I may put this one off for a couple of years hoping that better and cheaper RGBW sources come out that can do what I want.

It'll be good to have that link when I get there.

I finally played with the display for GMLightings RBGW LED tape

I had the same idea, this could be great for varying the lighting but I wasn’t wowed. I can’t remember why it didn’t look like I was hoping. The colors on the the remote control look like they have the full color spectrum. I think it was hard to get an exact color. Theirs is only 64 lumens per foot. 

Theater style lighting is a lot of work simply to set the lighting to dusk. 

Low lumens

This will look like a bit of a tangent, but its not meant to be.  With all the discussion about LEDs, one hobby that is making amazing strides is aquarium keeping, so I hope this is relevant to the discussion, but forgive me if it isn’t.  

This is the business end of  the light being discussed here.  Not very many LEDs really, just a small array of high output LEDs with a microcontroller of some sort.  Here is a link to the company that makes these: https://www.aquaillumination.com/products/prime

At around $300, they are still probably too expensive for model railroad use, but they do night, sunrise, sunset, full daylight, simulated clouds, thunderstorms, lunar phasing, etc.  very well. I have them on a couple of my reef tanks and they are awesome for photosynthetic critters.

Being that they are just an array of LEDs with a controller.  I’m guessing that a large portion of the retail price could be saved with a DIY project, and I would guess there are folks building their own using an Arduino or something to trigger LED arrays.  Also guessing there will be  internet  resources in the cloud reef community focused on that very thing.  I opted for convenience with this consumer-proof device.  What is really cool is that users can share their programs on the manufacturer’s website.  I borrowed my program from a biologically informed reef enthusiast in Hawaii, and turned things down across the board as my tank is so small.

Here, a “moonlight” shot.  The Anenome shrinks at night - it is about 1/3 of it’s daylight size here.  Some nights the clowns get right inside there, and the critter wraps them up in a tight hug and they all sleep.

The amount of each frequency is extremely tunable on a 24 hour clock.  A screen shot of my current settings for a daily cycle on my nanoreef, and the tank lighting at a given moment in the clock is shown below.  

It’s all bluetooth from a mobile app.  The other one I have at our farm is older and is IOT for remote programming.  The tank, sadly is empty owing to a too-high proportion of copper in the town water we have to haul from time to time.  The older one has settings for random overcast, cloud movement and random thunderstorms between certain hours of the day.  The one shown above, I can program which is what all the peaks and valleys are in the screen capture.  The “sun” gets partially blocked by cloud!  I wonder if the fish have clued in yet?

These also simulate lunar cycles and work really well.  I have all sorts of things spawning in my tank.  I spent a bit of time in my undergrad years in marine biology so learned a bit about critters and their amorous affiliations with the moon.

No doubt the extreme levels of UV required in a tank would want to be turned down to pretty much zero on a layout so as to not fade paint, etc.  This program is doing wonders for the Anenome and corals.  My moonlight intensity rises overnight which is likely why my starfish, snails, worms, corals, etc. spawn so readily. 

There is a feature in the app to test run all or part of the 24 hour cycle .  Here are a couple of Youtubes showing my program in action.  The first is a bit of an overview with a quick sweep through the 24 hour program:

The second a bit more gradual. 

These aquarium lights are available RTR in wide strips as well from various sources for longer tanks, but are well over a grand.  It would be very interesting to explore what is going on in the DIY community and how it might be applied to layout lighting.  
Full on daylight mode, all these lighting fluctuations from the videos have the corals upset!

Sorry about the dirty glass.  my caretaking crew is slacking.  Look at all the fisioning starfish! 

It must have been a full moon in the cycle in the last few days, there is lot's of spawn on the left side glass!