I recently converted all 300+ lighs in my house to LEDs (see My adventures in LED home lighting). In my master bedroom are two bookcases with under-shelf light strips made up of small incandescent bulbs. They work, but have a nasty trait of causing the shelves to pop and creak for over an hour as they heat up the wood. Plus they are incandescent... that just won't do for the techno-villa.
If you've ever trolled Ebay, etc for LED stuff you have seen those LED strip lights. These are strips of LEDs with ballast resistors mounted on an adhesive backed flexible strip. They are 8mm wide and up to 5 meters long. You can get them with 60 or 120 LEDs per meter. The LEDs are configured in groups of (usually) three LEDs and a current limiting resistor. The LED groups are connected in parallel along the length of the strip.
You can cut the strips to any length that is a multiple of three LEDs. You solder wires to small copper dots to make the new connections. You can get the strips in many colors. If fact you may get them in colors that you did not order. I first ordered warm white, but got a neutral-cool white.
The strips come in two types: "water-proof" and non-water proof. AVOID THE WATERPROOF STRIPS LIKE THE PLAGUE! They are waterproofed by coating them in a semi-cured epoxy booger. It stinks. It sticks. It sucks. And it WILL KILL THE LEDS!. Also, if you cut the strips, it takes forever to clean it off the electrical contact points.
Back to the IT WILL KILL THE LEDS... I ordered some non-waterproof strips and got shipped waterproof. Bummer, but OK. I made some lights out of them and ran them for a few months. After that, the LEDs were almost non-visible DEDs (Dark Emitting Diodes). A couple of LEDs on each end of the strip were visible. The epoxy booger had cracked and darkened (but not enough to obscure the LEDs). I stripped the epoxy off the tops of a few LEDs and they were just as dim. My theory is the epoxy traps heat that kills the LEDs or somehow leaches into the LED package and kills them.
Later, I found one waterproof LED seller that mentioned the problem with epoxy waterproofed strips. He sold a version that was in a silicone tube that allegedly does not have the problem... sound reasonable, but buyer BEWARE if you need waterproof LED strips.
When you get the LED strips, they come on a reel. The seller most likely has terminated one end of the strips with wires and maybe a barrel connector. I bought 5 meter reels of 600 leds. Rated at 4 amps. I hooked up 12V to the wires and voila.. 2 amps. Huh? Another Sino-fraud rating ripoff from our friends in Old Cathay? Well, not exactly. I checked the voltage/current over a 3 LED segment near the wires. The LEDs were drawing 16.5 mA. The full strip should have been drawing 3.25 amps... Hmmm.... It turns out that the flexible copper tape conductors that the LEDs are mounted on cannot handle the current. There is a big drop in voltage down the length of the strip. The groups at the far end of the strip were getting less than 10 volts.
Well, why not just crank up the voltage so the strip draws the full rated current? Because the LEDs nearest the power connector will be seriously overdriven. The only way to properly drive the strips is to connect the "+" voltage to one end and the '-' voltage to the other end. This will assure that each LED group on the strip receives the same voltage. You still have to crank up the input voltage well past 12V to offset the voltage drop in the copper foil connectors. Driving a full 5 meter, 600 LED strip from each end required 14.25V to get 12V to the LEDs. So around 1/4 to 1/3 the power you dump into the strip goes to heating copper foil.
You can drive shorter pieces of the strip from one end since the voltage drop won't be too bad, but beware if you want to drive longer pieces.