I've been invited to go to a friends 40th birthday party and want to take a present that will be appreciated. He is a bit of a tech head and has also been known to get drunk and shout PANTS! a lot. So I've decided to make him a pair of flashing LED disco pants.
The idea is that the LEDs will be controlled by an Arduino so they can be flashed in sequence. To achieve this each LED on the pants will be separately addressable but to do this without a large number of unnecessary wires in the undergarment I will be using the Charlieplexing method to power them. There will be four strings of 12 charlieplexed LEDs
and each string of 12 LEDs will only need 4 wires. So a total of 12 wires will be needed to control the whole array of 48 LEDs.
The other advantage of multiplexing a Charliplexed array of LEDs is that only one LED per array will be ON at any one time. The down side to this is that they will have to be rapidly flashed or multiplexed to give the illusion that more than one is on at a time and that is more complex code on the arduino. However the big benefit is in power saving as there will be a potential of 4 LEDs on at any one time (one for each 12 LED string) which will lower battery consumption enough to get away with using a 9 volt battery.