I'm thinking about building a clock using 60 RGB LEDs..!
I'm going to use 60 blue (seconds), 60 green (minutes) and 12 red (hours) so that means a total of 132 LEDs I need to control!
Only one LED of each colour needs to be turned on at any time.
I'm not completely sure yet what would be the best way to control them, so far I have been thinking about using an AVR to control something like the CMOS 4514 or a 74LS154 (4bit binary to 16 line decoder), this way I would need 9 IC's (4 for seconds, 4 for minutes and 1 for hours).
This would be okay, but maybe someone out there has a better idea? Charlieplexing is pretty much out of the picture since RGB LEDs are usually common cathode (or common anode)..? And it would probably be very complex with 132 LEDs.
My problem with the 4-to-16 decoders is, looking at the datasheets I see values for the output current in ranges from ÂµA to 8.8mA... ÂµAmps are useless, 8.8mA is probably acceptable (I have not bought any LEDs yet). I'd love a chip that would give me something like 20mA on the outputs! ;)
Any advice is appreciated!