All About LED's

[Blender]

I'm no pro, but I'll tell you what i know. I've never used a tlu-01, but I build my own helicopter blades with LEDs on them to fly at night.

Leds require a specific forward voltage (Vf) to light up. It's usually 2-5 V, but there are some that run on higher voltage. If connected backwards the LEDs won't light up, but they won't be damaged. The current draw is generally around 20mA, but it can vary by color/size/make. Check the datasheet provided by the vendor. There are lots of different size/shapes of LEDs. I usually work with surface mount (SMD) which come in 4 digit size codes (ex. 0603 which is 0.063" x0.031"). Other sizes are 3mm and 5mm round like what's usually at radioshack. Visible angle is another important feature. Some LEDs have very narrow light beams like 20 degrees. That might me fine for headlights, but if you want lights along the side of your trailer something with 130 degree or more would be better.

How i build an array is first select LEDs with a Vf lower than my battery i'm going to use. I use off-the-charger pack voltage instead of the nominal voltage that's printed on the battery pack. A trick i use is to connect various LEDs in series until the sum of the Vfs is about equal or a little higher than the battery voltage. This will let me run the LEDs with no resistor. There is a little risk to this as if my wiring shorts out there will be no resistor to reduce the current. I killed one of my 160mAh lipos when my blade mounted LED/wiring came loose and shorted out the battery pack. The standard/safer method is to use a LED calculator where you type in the Vf, current and battery voltage then it'll tell you what resistor you need. There's also a version that handles multiple LEDs by the same people.

If i want to add a ton of LEDs with all kinds of colors and sizes i break the work into small pieces. Say i'm using a 3S lipo thats 11.1V nominal, 12.4V fully charged. If i wanted eight amber LEDs and the each had a Vf of 3.1 V, I'd make a string of 4 LEDs in series. Then make another string of 4 amber LEDs and connect the two strings in parallel to the battery.

Key features:
Vf Forward Voltage
Size/ mount type
viewable angle
brightness measured in mcd (milli-candela). I like 100-200 mcd

The cheapest LEDs i've found are from china Ive never ordered from SatisTronics personally, but a few of the heli guys have. They are considerably cheaper than Digi Key, Superbrightleds or Allied Electronics. I'd encourage you to order a few and just play around with a soldering iron and a battery. You'll smoke a few LEDs, but they're only a few cents each . I use conductive copper tape and solder to connect SMDs and small wire with headsrink to connect the round LEDs.

[CorbettTrailers]

Originally Posted by Blender

I'd encourage you to order a few and just play around with a soldering iron and a battery. You'll smoke a few LEDs, but they're only a few cents each.

This is a very good idea. Thanks.
And thanks to everyone else for all the info. This is going to be very useful, exactly what I was looking for.

Thanks Again,
John