Sunday, June 15, 2014

Continuing development of LED lighting

It's been a couple of months since I've posted anything on this blog.  During that time I've been working on my Japanese Ntrak module quite a bit and also completing some DCC decoder installations.

Where I left off last time was that I had found a great little panel on ebay that contained 48 SMD LED's and that is intended to use as replacement interior dome lighting for vehicles.  Then I tested them by taking a series of photos of one of the Ntrak modules with different color locomotive, freight cars, and building to determine if the colors would come out true.

Another thing that got accomplished with the LED panels was they got installed in the travel trailer and in May we took a little trip and they worked out quite well.   One thing I've been aware of is that women are much more critical of the color temperature of lighting and with the lights in the trailer meeting with approval of both Nona and a woman friend of ours,  I have more confidence that these little panels are going to be good for the layout.

I mentioned that I got these on ebay.  Buying them in packs of 10 gets the price down to about $2.00 per panel.  There are both the white and warm white types.  I intend to use the warm white type for the layout.  At that price point, you can't expect the best quality control.  About one out of 10 of these have the red and black wires backwards which is easy to correct.

Using these small panels, I wanted to have a way to mount them in groups which could be customized depending on the area to be covered.  Most of these will be mounted under cabinets which might be of different widths.  In the area where I am starting there are four 30 inch wide cabinets each with a pair of 15 inch wide doors.  So for this first section, I came up with a 14 inch long module holding 5 LED panels and built 8 of these to match that section of cabinets.  One of these units is shown in the photo below.

This next photo shows some of the construction details.  The mounting brackets are made from brass strip and angled so that the light is not shining in the operators eyes.  The angle is only slight so the vertical space needed for the lights won't change much.  The angle can also be adjusted by bending the brass mounting brackets.  The planned 3 inch valance placed along the bottom of the cabinets will cover the height of the modules.  Notice how the second panel from the left is wired backwards.  That is how I corrected for the ones that were wired backwards on the panel.

Some calculations

Now that I've got an idea of how to use these LED panels, I needed to determine how many it will eventually take to light the entire layout, how much they will cost, how much power they will consume, what type and how many power supplies will it take to light them all up.

First the cost:
The planned visible mainline run which would receive full lighting is 62 feet.  At 4 panels per foot thats 248 panels needed.  That's over 11,000 indiviual LED's !  At $2.00 per panel, it's going to run about $500.00 spent over time.

Then the Electrical:
I had measured the current drawn by a single 48 LED panel at 75ma with 12 volts applied.  With 5 panels on each of these modules, a single module would draw 375ma.   8 modules on this 10 ft section of layout would then draw 3 amps.  I've seen a lot of laptop power supplies on line and in my local electronics surplus store rated at 5 amps and my next step will be to pick up one of those to try it out on this first section of lighting.