# Planning to design low voltage lighting



## SE18 (Feb 21, 2008)

Got a 200W transformer (steps down to 12v) with auto or manual timing for garden RR lighting. Plan to install next weekend thru side of house on GFI, which I'll do. Neighbor has same setup but I'm not enamored of his lights. They're too bright and the design of them casts these shade rings on the ground.

I went to Lowe's and was disappointed at the lighting assortment. The styles didn't fit a railroad theme and the price was really really high compared with solar. 

I'm thinking a combination of spotlight, downlight, etc, on much smaller lights. Railroad theme would be a plus. Any low-cost, railroady looking low-voltage lighting someone can point me to? 


Thanks

Dave V


----------



## Tahoe1 (Nov 10, 2008)

I use the same sort of set up.I use the lighting transforrmer to power the lights (both incandescent and LED) in my buildings.
I also power the 1:29 scale street lights that I made again LED and Incandescent. 12 Volts.
I could send you a picture of what I made and guide you through making your own if you're interested.
Bill Wright
[email protected]
@import url(http://www.mylargescale.com/Provide...ad.ashx?type=style&file=SyntaxHighlighter.css);@import url(/providers/htmleditorproviders/cehtmleditorprovider/dnngeneral.css);


----------



## Dan Pierce (Jan 2, 2008)

I use the 4 watt bulbs in my outdoor light system. 7 watt bulbs were way too bright. I also added a 1 ohm 10 watt resistor in series to the output of the power pack to reduce the lamp voltage


----------



## Greg Elmassian (Jan 3, 2008)

The resistor wastes power, and thus limits the maximum number of bulbs... why not try using 2 bulbs in series, that would dim them down, and give you twice the number of lights on the same transformer. 

Of course, it's a 200 watt transformer, but those transformers drop their output voltage radically upon load... 

Greg


----------



## SE18 (Feb 21, 2008)

my neighbor is an electrician. For tiny lights, he told me LEDs are the way to go. I plan to bury the wire in concrete. He said LEDs last forever so wouldn't need to be changed. I'm a bit skeptical. Thanks for the tips everyone. I haven't started on the project just yet. I think by next spring I'll be posting photos and stuff 

DaveV


----------



## Greg Elmassian (Jan 3, 2008)

LEDs are great, but now you need a different power supply, unless you start putting them in series... and you will need separate current limiting. 

Put conduit in, don't bury wires directly into concrete... LEDs may last a long time, wire does not, moisture and corrosion can and will happen. 

Just to put this in perspective, how many lights or structures are you planning on using? 

Greg


----------



## SE18 (Feb 21, 2008)

Hi Greg, 

I don't know yet. We've first got to install the GFI protected outlet, then, I'll do a dry run with lights. I don't want to overkill the lighting. Subtle is good. There will be some 4W area lights and then lights going around my aqueduct, which is still under construction. Not many structures; none right now but might be a few later. Thanks for these invaluable tips!


----------



## Rod Fearnley (Jan 2, 2008)

I have two sets ( two transformers) of Malibu garden lights.I have them up on the fence above the RR. I also use blue theater gells inside the lamps to get a midnight blue illumination over the RR.


----------



## Greg Elmassian (Jan 3, 2008)

If you are going to use the unregulated AC transformer for powering your LEDs, you might want consider the cost of rectifying and regulating the power supply. 

LEDs need a "dropping resistor" which actually regulated the current through the LED, but it's also based somewhat on a stable voltage. Those unregulated AC transformers have an output that varies widely with load. 

breadboard up your circuits first. 

Don't get me wrong, I think LEDs are superior in many ways, but you will find they have their difficulties too, like tending to make a spot beam, rather than a diffused sphere of light... and getting the current right. 

Regards, Greg


----------



## shaneclara (Dec 27, 2007)

LED's are nice but make sure you protect the prongs very well from the elements or they will rust off. On our layout we use a combination of LED's and Incandescent 194 peanut bulbs. The LED's don't spread light as well as I like. The outdoor layout has operational street lights that I made from brass tubing. Each peanut bulb uses 2.1 watts and I have 15 at the moment ... that's only 30 watts total and they spread light nicely. They've been on our layout for the last 4 years, exposed to the elements, working every night and I have yet to replace a bulb. I just entered a night shot for the photo contest.


----------



## ddevoto (Jan 22, 2008)

Here's a link to "Ready to Use" LEDs. I use them right off DCC track power up to 25Volts. They're inexpensive and easy to install. 

http://www.modeltrainsoftware.com/ledoutdoor.html


----------



## SE18 (Feb 21, 2008)

That LED site looks really good. To give you a sense of what I want to do, I’d like to string LEDs (but keep wires hidden along this aqueduct--which forms a huge loop (if photos post)). So embedding them in concrete not so good idea? Top of aqueduct would look awesome at night with LEDs IMO, keeping light at low levels for subtlety


----------



## dieseldude (Apr 21, 2009)

That dog is way out of scale!!!!


----------



## Phippsburg Eric (Jan 10, 2008)

He looks freindly though!!!


----------



## Mike Reilley (Jan 2, 2008)

I'm looking at using a ATX power supply to provide power for the lighting circuits on my GRR. Has anyone tried using one of these? These are the power supplies used in desktop computers. They provide plus and minus 3.3v, 5v, and 12v outputs. Power output looks OK...and the 12v pins can now supply up to 20A (240VA total). The output is regulated...and I can see lots of them on eBay for under $20 including shipping. The output is via a connector, so replacing one means just unplugging a cable. It's small...6 × 3.4 × 5.5 inches. The cables are cheap...in the $5 range. They plug into 120v AC and have a cooling fan built in. 

I realize they must be put in a water tight container if you're putting it outdoors...and that means thinking about how to get cooling air inside...but overall, seems like a good way to go for GRR power for lights and annimation.


Thoughts?


----------



## Dan Pierce (Jan 2, 2008)

The computer supply will work, the minus voltages do not have much power, but the positive 3.3, 5 and 12 volt do. 

The 3.3 is great for leds with a small resistor in series with each one, a 3 volt led would need 30 ohms for 10 ma and would give less than 20 ma for a 2 volt led. Common size is 27 or 33 ohm and 1/10 watt would be great. 12 volt output can drive the outdoor 4 watt bulbs directly.


----------



## Mike Reilley (Jan 2, 2008)

I think it would be a 330 ohm resistor....3.3v / .010 amps (10 ma) = 330 ohms.


----------



## Greg Elmassian (Jan 3, 2008)

on 3.3 volts, that calculation is very poor, because you are ignoring the voltage drop of the LED itself. The voltage drop of the LED is now a extremely significant portion of the supply voltage. 

In ANY circuit, the voltage drop across the resistor AND the voltage drop across the diode equals the supply voltage. 

When people are dropping from 12 volts, often they ignore the voltage drop of the LED, but that is wrong. The calculation yields a different current than desired. (but since the current is less, nothing blows up) 

Check the LED calculators online, you will see that they ask for the forward voltage drop on the LED. 

Greg


----------



## toddalin (Jan 4, 2008)

When dealing with >12 volts (e.g., variable track power), I usually ignore the voltage drop in the calculation (adds a bit of protection). If


----------



## Greg Elmassian (Jan 3, 2008)

Except that white leds are often over 3 volts drop... red leds and green ones are around 1.7 and up... 

Safe assumptions are 2v for most leds, and 4 volts for white. 

I normally either get the specs or measure it, easy to do. 

Greg


----------



## Mike Reilley (Jan 2, 2008)

Thanks Greg....for some reason I thought the voltage drop across an LED was the same as a diode...and, it isn't. As you point out, there are different drops for different colors.


----------



## Dick Friedman (Aug 19, 2008)

To answer the original post, if you've got voltage reducing transformers for low voltage garden lighting, a couple of suggestions. Use your garden lights, but use the 4 amp bulbs -- colored ones if you can find them. Malibu is a brand name. 

I use the same transformers at the same time to power by building lights. For buildings, I go to Radio Shack and buy 14V screw in bulbs and bases. I mount the bases on walls, and wire the base into the garden RR light cable with "suitcase" connectors. 

Those 14V bulbs don't get white hot, but rather a nice yellowish. I wire everything in parallel, not series, so each bulb gets 14V. 

As for LED's, I love them, too! Big transformers like you've got will let you power dozens of LED's, but you'll need them, as they put out very focused, very small points of light. With AC transformers, you'll only get light 50% of the time, and you've got to bring the voltage down to 3 - 5 volts.


----------



## RimfireJim (Mar 25, 2009)

Mike, 
I sent you a PM.


----------



## SE18 (Feb 21, 2008)

thanks for all the awesome info here. Haven't started yet, but promise it will happen, eventually. 

Also, here's an interesting related link I found 

http://www.btcomm.com/trains/primer/lighting/led_garden_lighting/led_garden_lighting.htm 
Dave


----------



## Dick Friedman (Aug 19, 2008)

Paul knows his onions. He's built a lot of stuff, and he knows how to stretch his [email protected] url(http://www.mylargescale.com/Providers/HtmlEditorProviders/CEHtmlEditorProvider/Load.ashx?type=style&file=SyntaxHighlighter.css);@import url(/providers/htmleditorproviders/cehtmleditorprovider/dnngeneral.css);


----------



## JackM (Jul 29, 2008)

With all respect to the voices above, I don't see any advantage to lighting the layout this way. Seems awfully complicated and, perhaps, even overly permanent. I've made enough changes to my layout in its brief existence to prefer "self-powered lighting" everywhere.












Admittedly, the solar panel isn't _totally_ hidden, but last year this building was the local passenger station, next year it'll be a residence somewhere (it started life as a pair of bird feeders from Lowe's).












This solar panel is mounted on the rear of the (unfinished) work shop for the yard's RIP track - not visible to visitors.












The track control panel uses four LEDs, four panels. Okay, they could be aligned better.

Admittedly, solar power has the disadvantage of dependence on amount of sunshine. But very few days last summer failed to provide sufficient lighting for at least a few hours of after-dark running. The most difficult part is cutting and filing down the panels to fit. But then, I buy the lawn lights when they're on sale for $2-3 each.

JackM

SE18 - Your aquaduct is seriously impressive. The Romans would be proud.


----------



## SE18 (Feb 21, 2008)

Hi Jack, are you the same Jack from Rochester NY? 

Fortunately or unfortunately, I used to have a lot of sunlight but our area in summer (n. va.) gets oppressively hot and I planted a lot of shade trees, which pretty much have added shade everywhere, not to mention that 40% of the track goes below my deck. Even so, I do find that my solar lights capture enough light to come on dimly at night. 

I suppose I could mount a solar collector on the roof or something, but at this point, I'm ready to give low voltage a try, especially for the really dark areas. It has a timer too so cuts off (photovoltaic) when daylight arrives. I haven't yet installed it.


----------



## JackM (Jul 29, 2008)

Hmmm....I've been on MLS a bit over two years now, I'm in the Roch area, but always used the M because someone here already snagged "jack". Don't know if he's from Roch also.?? 

I've heard it said that Roch. is one of the grayest places in the country, so i figured EVERYONE has more sun than we do. I didn't factor in the possibility of excess shade trees. I can understand the need for a wired system, after all. Or a small chain saw. 

JackM


----------

