Layout Lighting and DCC

[daniel_leavitt2000]

I have been experimenting with lighting for my layout room the past few months. My initial idea of using rope lights resulted in lighting that was too dim to be useful. I then found various LED tape lights:

http://www.amazon.com/Flexible-Daylight-Waterproof-Accessories-Included/dp/B00MHLIFO8/ref=sr_1_16?ie=UTF8&qid=1422483883&sr=8-16&keywords=tape+light

The lighting on these is directed downwards and they are available with brighter LED bulbs. The sample I received was very bright, able to light up the area around it quite nicely.

The system is 12 volts and my 8' sample came with a 5W power supply. Which means that each foot would equal to about .625 watts. For the layout I will need 105 linear feet in each of the following colors: White, Warm White, Orange and Blue.

I have a few concerns: First, will the delicate flat wires in the tape be able to handle the load (about 70w) of 105 feet of LEDs? Second, I need to add dimming. I could just use a variable resistor, but it would be nice to be able to control this from DCC. Are there any accessory controllers out there that can provide up to 12V at 70 watts? If not, where can I find a variable resistor that can handle the power?

[John]

I got one of these, and powered them directly from the DCC bus ..

[daniel_leavitt2000]

Can the bus take that much drain? I need to power 280 watts worth of lighting (70 watts for each of the four colors).

[John]

Beats me .. I just know it works ..

[Scottl]

I have 5 m of 5050 LEDs on a strip (600 total, double the density of the example you posted) and I am waiting for a 120W 12V power supply for them. They will take that much to produce near their rated lumens.  With a few watts, you are getting a much dimmer result.

I will split the LED tape into sections and have 12V feeders because the flexible circuit board loses a lot of voltage due to the limited thickness of the traces.  That way I have about 2A going through wire to each strip so I don't get progressive dimming down the length of the tape.

[C855B]

Can the bus take that much drain? I need to power 280 watts worth of lighting (70 watts for each of the four colors).

No. 280W/12V = 23 Amps. Dat's alotta amps. (Yes, DCC is 15V, but LED strips are computed at 12VDC and power conversion factors will eat most of the difference between 12VDC and 15VAC.)

You need a dedicated power supply or supplies for those puppies, Daniel. Also, make sure your lighting controller can handle that much. Most can't. Plus, like Scott mentioned, LED tape strips can't handle that much power if connected as one big string. 10M strings are more or less considered the longest practical, and everything - power supplies, controllers and the tapes themselves - are all designed around that maximum. You can feed multiple strings from a single honkin' power supply, but like I mentioned there's the controller issue, and each 10M run will need its own drop.

[daniel_leavitt2000]

Mike, Scott thanks for the replies. That was just what I was looking for.

I am using double density LEDs for the daylight and warm white colors and single density for the blue and orange as those will only be used as accent colors for sunset and night operations.

Luckily I have wiring for 4 different lines with an access point above each corner of the layout. That will keep the length under 30 feet for each segment.  While the wiring was done to handle 120V, it should be perfect for high draw 12V. One 70W power supply for each color should do it.

Anyone know of a good dimmer/variable resistor that can handle 4-5 amps at 12V?

[Scottl]

I tried running my 5m strip with 12V from a single supply and I could see the difference in lumens from one end to the other due to voltage drop.  30' (~10m) is a long ways to run amps through the copper traces.  If you can, I would try it out with your wiring plan before committing to it.  You may  wish to find a way to get more feeders to the LEDs.

It is kind of ironic.  There are people on this board that solder leads to every section of track, yet we (I'm guilty of this too!) contemplate a 5 or 10 m run.

[Scottl]

While this discussion is going on, what types of fixtures are available for LED strips?  I was envisioning ripping plastic pipe and covering the inside with aluminum reflective tape.  Is there a better idea?  There must be 

[daniel_leavitt2000]

Since this would be behind a valence, I was just going to stick it up with 3M automotive double sided tape. You know, I could just use 15' sections and run a bus wire along each side of the strip to the next section. That should help, right?

[peteski]

White paint does a better job of bouncing light than reflective tape.  But the LEDs are already directional, there should not be need to put the strip in any sort of reflector. Maybe to actually reduce the light emission angle?

I thought the wide copper traces would not have much voltage drop over longer runs. But if they do, wh not parallel the strip with some 12 AWG wire, then connect it to the strip every couple of feet with short jumpers.

I'm also puzzled with John's setup. First of all, it seems to be a waste to have a pulsing DCC signal from an expensive booster "wasted" for powering LED lights. Why not just use a cheap dedicated DC supply?  DCC signal is not buying anything (not like the brightness can be controlled through DCC).  Plus (since LEDs need DC 12V) they are running at roughly half brightness: The DCC signal flips polarity (at about 50% duty cycle) and the LEDs will only illuminate on one of the cycles (so they are off half the time).

[conrail98]

While this discussion is going on, what types of fixtures are available for LED strips?  I was envisioning ripping plastic pipe and covering the inside with aluminum reflective tape.  Is there a better idea?  There must be 

Yes, the joint Philly/NJ NMRA meet recently had a great demo on this. One, they have sticky backs so you can mount them under benchwork or along a valence, anything hard-ish will allow for it to stay up. The gentleman giving the demo pointed out that he's been using, behind his valence, J channel from the local big box store, like this. You screw the J channel into a mount then bend the channel 45 degrees so the lights shine down at an angle. He's done this for his under layout lighting and can pretty much have just these strips on and not need other room lighting for an ops session,

Phil

[Scottl]

Thanks, that is a really good idea.  I don't have a valence to work with, but I wonder if something like this is a way forward?  Interesting.

[daniel_leavitt2000]

Pete, that's what I was thinking....


Amber is the LED lighting strip.

[peteski]

That should work Daniel.