I've always been looking for a reason to use an Altoids tin as a project box, and this project seemed to be it. - Altoids tin - 2 AAA battery holder from Radioshack. - three way toggle switch that I scavenged. I used a three-way switch becuase I plan on eventually adding a circuit that will make the light have a blinking mode. If you don't care to add this extra complexity to the light, just buy a simple SPST on-off switch. - three white, 3V LEDs given to me by a friend.
LED Parts LEDs come in all shapes and sizes, but the 3mm T-1 or 5mm T-1¾ are probably the most common. The die is an itty bitty cube of semiconductor, the composition of which determines the color of the light given off.
Running Christmas lights off batteries (DC power) Way back in the 1990s this page turned readers on to (new and rare at the time) LED Xmas lights. LEDs are important when running lights off batteries, because you get up to sixteen times the battery life vs. regular bulbs. I also showed readers how to rewire any strand of AC lights (normal or LED) to run off batteries.
One of the bummers of Christmas is trying to get the strings of lights to work. The biggest culprit are the strings that are connected in series. These are usually the strings of so-called miniature Christmas lights with the push-in bulbs.
The LED series/parallel array wizard is a calculator that will help you design large arrays of LEDs. The LED calculator was great for single LEDs--but when you have several, the wizard will help you arrange them in a series or combined series/parallel configuration. The wizard determines the current limiting resistor value for each portion of the array and calculates power consumed. All you need to know are the specs of your LEDs and how many you'd like to use. <p style="text-align:right;color:#A8A8A8"></p>
Most recent update or addition in anything below of mine 3/24/2013, with the latest noted update on links offsite from here 3/23/2013. Efficient and bright LEDs! Efficiency of some good ones and some runner-ups in lumens per watt, millicandela and beam angle ratings for some of these, where to get most of these.
All LEDs require current limiting, without a current limiting mechanism the LED will usually burn out in under a second. Adding a simple resistor is the easiest way to limit the current. Use the calculator below to find out the value of resistor you require. For example if you are wanting to power one of our red LEDs in an automotive application you would see that the typical forward voltage is 2.0 Volts and the maximum continuous forward current is 30mA. Therefore you would enter 14.5, 2.0 and 30 into the Single LED calculation box.