LED Candles

Forrest

My LED Candle controller is designed to produce a realistic looking 'flame' - suitable for use in a Jack-O-Lantern. The design was based largely on Jon Williams Nuts&Volts column #126 from October, 2005 - which you can download at
www.parallax.com/html_pages/downloads/nvcolumns/Nuts_Volts_Downloads_V6.asp

My design is different from the original because it was built on a seperate board and it's designed to work with a Parallax HomeWork Board and the integrated BS2. The LED Candle controller is built on a 1 3/4" x 1 3/4" perfboard (Radio Shack 276-148) and consists of a ULN2803A, (3) 220 uF, 25V electrolytic capacitors, (3) 390 ohm, 1/2 watt resistors, a .1uF monolythic capacitor and a 10K potentiometer. P0 connects to the 10K pot and controls the flicker rate of the LED's, and P1, P2 and P3 each control (2) high intensity LED's - yellow or red. Each set of (3) LED's are connected to the controller with 4 conductor, solid wire telephone cable. The controller and LED's are connected to Vin and Vss on the HomeWork board. A 9V battery lasts about 7 hours, while an 8 cell NiMH battery pack (10V total) lasts about 45 hours.

I've used these LED Candles for 2 Halloween's and they've worked well. The only difficulty I had when originally contructing the candles is my first set of LED's weren't bright enough. Once I switched to 5000 Mcd high intensity LED's - the candle light was a lot brighter.




Post Edited (Forrest) : 11/19/2006 6:12:44 AM GMT

sam_sam_sam

Forrest

This a cool project did you use the the same wiring that·the
·Jon Williams Nuts&Volts column #126 from October, 2005

Please let me know Thanks For the info

Sam

Forrest

I used the corrected schematic for column #126 - which is the one linked to in my message. The schematic that appeared in the actual magazine had an error - so use the download instead. I substituted the ULN2803A for the ULN2003A (in the original) because that's what was in my parts drawer. The only difference between these two chips is one has 8 input/outputs while the other has 7 inputs/outputs. I'm only using 3 inputs/outputs, so it really doesn't matter. The only other electrical change was I used 390 ohm resistors instead of 330 ohm in the original - because that's what I had available.