Articles - Electronics: LED Strip Lighting
03/02/2018
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There are companies that sell specialized versions of LED strips for things such as passenger cars. However, if you have the ability and desire, you can save a ton of money by buying these 16-foot strips. You can find them on Amazon, eBay, as well as on the retailers' web sites directly. The package shown in the photo is representative of what you get. I desolder the plug off of one end, and throw the packaging and reel away. All you need is the strip of LEDs themselves.
LED Strip Lighting
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This photo shows the back of the package of another brand of LED strips I've bought. LED strips come with various types of LEDs installed. The larger the LEDs mounted on the strip, the brighter they are, the more expensive they are, the more power they consume, and the hotter they get (yes, they do get warm to the touch). Additionally, like conventional LEDs, they come in a variety of colors. The ones in the photo above are "neutral white" (4000K). The ones in the box in the photo below are "daylight white". For my layout lighting, I prefer the latter. However, for interior lighting of our models the more yellowish colors might be more appropriate. The size of the LEDs is marked on the packaging. The ones in the photo above are marked as "3528". Basically, those numbers are the width and length of the LED in millimeters, if said millimeters are multiplied by ten. So, the ones in the photo above are 3.5mm x 2.8mm. The LEDs contained in the box below are "5050". They are 5.0mm x 5.0mm. Typically, there are 300 LEDs on a 16-foot strip. There are cheaper strips with fewer LEDs, or shorter strips available as well. The more LEDs, the brighter the whole strip is, and, of course, the more power the strip requires.
LED Strip Lighting
Speaking of power, be sure to get a power supply that can handle the LED strip. When you buy the LED strip, it will state on the package how much power it requires. It is termed in "watts" (or a capital "W"). Power is calculated by multiplying voltage times current (P = V x A). These LED strips are, typically, 12 volts (they do also make them for 24 volts, but those are mostly intended for high-power applications). To calculate the current that the power supply must be able to provide, divide the power by the volts (A = P / V). Using the blue-box LEDs above as an example, the package says that that strip requires 72W. So, we divide 72 by 12 volts and we get 6 amps. The LEDs at the top of this page use 24W, so they only need a (24 / 12 = ) 2 amp power supply. I highly recommend that you get the switching-style power supplies (used for laptops, or similar). They are small, can be wired up directly, don't cost very much, and, most importantly, they provide a much cleaner power source (as compared to standard wall-warts), which LEDs prefer. The one shown in the photo below is rated for 12 volts at 3.33 amps. So, it is capable of handling up to (12 x 3.33 = ) ~40 watts of power. So, this power supply would be easily able to handle the entire LED strip in the top photo, but not the one in the blue box.
LED Strip Lighting
If you don't need the entire strip, they can be cut with a pair scissors at intervals of, typically, every three LEDs. The photo below shows one such example. So you can make your own strips of LEDs for situations such as interiors for passenger cars, cabooses, and structures by cutting the strip to an appropriate length. There are small soldering pads on either side of the cut line, so you can solder wires to the strip. Make sure to keep the pluses and the minuses together. I use red wires for the plus and black wire for the minus. Typically power supplies have text on one of the wires, which is usually the plus one. A quick (very brief) test will either cause your LED strip to light or not to light, to verify which wire is indeed the plus. Once you have done so, how do you calculate the power requirements of that new strip? The strip shown in the photo below came from the LED strip shown at the top of the page. That strip has 300 LEDs, or 100 groups-of-three LEDs. So, if 300 LEDs requires 24 watts, then each group-of-three requires (300 / 3 = 100; 24W / 100 = ) 0.24 watts. So, it is then just a matter of multiplying that number times the number of groups you have in the strip.
LED Strip Lighting
This photo shows an example set-up for lighting my layout with LED strips. The one in the back is a section of the strip shown at the top of this page (lower wattage and more yellowish color), and the other three all use sections from the blue box above (the "5050"). These four strips completely light up the entire room for regular use.
LED Strip Lighting
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I ordered this power supply from LED Supply. It provides 200W of 12V power, which will be enough for all of my layout's lighting needs. The convenience of it being 12 volts is that I can also use it to power the LEDs in the structures on the layout.
LED Strip Lighting
The power supply, from left to right, features a green LED that turns on when the unit gets the 115V power, a fine-tuning potentiometer to control the output voltage (mine was exactly 12 volts), three slots of 12-volt positive and three slots for 12-volt negative outputs, the input ground, and the 115-volt input slots. The unit is fairly heavy and appears to be very solidly built. It comes with no instructions, but the unit's labeling should be sufficient. There is no way to mount it on anything, although there are a couple of exposed screw holes. The only "downside" is that the 115-volt connectors are fully open and exposed, so it is easy for someone to accidentally touch them.
LED Strip Lighting