It is a little wisp of a circuit that allows you to drive a blue or white LED from a low voltage. Normally, if you want to light up a blue or white LED you need to provide it with 3 - 3.5 V, like from a 3 V lithium coin cell. But a 1.5 V battery like a AA cell simply will not work.
http://www.evilmadscientist.com/article.php/joulethief
Here is a small tool able to write symbols or pictures on a screen. As a graphic LCD was too expensive, the solution adopted was to pilot a matrix of Leds. This way, with only some cheap transistors, common red Leds and a 16F628, the project is made possible.
http://users.picbasic.org/projects/FANCY%20LEDS/fancy_leds.htm
In this Instructables going to show you how to make creation, made up of lots and lots of LEDs, that is snake like shape, the LED Snake. LED snake is 1meter long, but you decide how long yours would be.
http://www.instructables.com/id/LED-Snake/
VUor Voltage Unit meters are often included in analog audio equipments to display a signal level in Visual Units. We are building a mono input VU meter in this project. You can build one pair to use them in stereo mode.
http://www.circuit-projects.com/audio-circuits/10-led-vu-meter-project-by-lm3915-and-lm324.html
Sporting an 8bit microcontroller clocking in at a maximum 24MHz and supporting 512 bytes of SRAM, 8KB flash, these rather lackluster specs are offset by four analog and four digital customizable advanced peripheral building blocks known as PSoC Blocks, and the ability to build a crazy small microcontroller project.
http://www.popsci.com/diy/article/2009-01/dot-dot-programming
Using a CMOS 555 timer and a single NPN transistor, you can drive as many as seven LEDs using a minimal amount of voltage and power from a single NiMH AA cell.
http://www.edn.com/article/CA6598371.html
This is a Dot Matrix Scrolling Sign. A Dot Matrix Display has an 5x7 led matrix with 5 columns and 7 rows. The display is controlled by the AVR microcontroller. The rows are controlled by PORTB of the microcontroller, while PORTD puts the data on the columns to make the characters.
http://www.avrprojects.net/index.php?option=com_content&view=article&id=79:dot-matrix-scrolling-led&catid=38:avr-projects-with-leds&Itemid=58
It is a modified a skateboard kit, added LEDs to the front and back, added PIC circuit, and covered with a comic book and custom graphics.You get a skateboard with eight white LEDs as headlights ,eight red LEDs as tailights all controlled via PIC microntroller.
http://www.instructables.com/id/Skateboard-with-PIC-microcontroller-and-LEDs/
This circuit is intended to signal when a plant needs water. A LED flashes at a low rate when the ground in the flower-pot is too dry, turning off when the moisture level is increasing. Adjusting R2 will allow the user to adapt the sensitivity of the circuit for different grounds, pots and probe types.
http://www.redcircuits.com/Page18.htm
This circuit was designed to provide that continuous light lamps already wired into a circuit, become flashing. Simply insert the circuit between existing lamp and negative supply.
http://www.redcircuits.com/Page26.htm