View Full Version : LED Decoration

12-21-2010, 09:32 AM
Hi everyone,

I was looking into something similar like, lighting decoration and effects they do at functions and meetings... :D. Yes it is a silly project but i have to decorate my work cubicle for the Christmas and New Year.

Could some one post their ideas if any? Also How to control many LED s individually, how do they actually do it in wedding hall decorations ?

Thank you.

12-21-2010, 09:53 AM
search for charlieplexing on google.

Should have been charlieplexing. Two alphabets were left out.. Search Again :)

12-22-2010, 09:11 AM
Hi Shobit,

I googled Char Plexing, but didn't understand what or how it is related to LED light control. Care to explain a bit?

Thank you.

12-22-2010, 08:04 PM
Long time back I began a project to control a matrix of 8x8 (=64) 5mm LEDs using 16 microcontroller pins. Have a look at this image http://www.flickr.com/photos/atroglodyte/5282517231/lightbox/

All PNPs and NPNs are off to begin with. A PNP and NPN pair ON, will light up a particular LED. F.e. if PORTB7 is set (NPN Q8 is ON) and PORTA2 is clear (PNP Q16 is ON), then this pair lights up LED57. The resistances in series regulates the currents in each LED (should be around 20mA for the usual 5mm LEDs). Cycle through all the PNPs and NPNs to switch ON/OFF the LEDs. You'll have to do this pretty fast so that the flicker is not too visible to human eyes.

12-23-2010, 08:33 AM
Some more information. try this link http://www.instructables.com/id/Charlieplexing-LEDs--The-theory/step4/Finallya-Charlieplex-matrix/