The utility store has started selling christmas decorations already, and I've got a hold of LED string lights. However, I've noticed they flicker A LOT, which made me want to hack them.
So, I've cut the controller, and I now have 5 wires to the LED's, and 2 from the 24volt, AC, unregulated wall-wart.
Using a diode-bridge and a voltage-regulator chip I salvaged from another device, I have a steady 12V DC to power my Arduino.
The LED strings are organized in 8 groups of 16 LED's, for a total of 128 LED's, of various colours (red, green, blue and orange). They are organized in a common cathode configuration for the first 4 groups, then in a common anode configuration for the other 4 groups.
That means that if I connect the common wire to +24V, I can light up the 4 first segments independently by hooking their respective wire to GND, and by connecting GND to the common wire, I can light up the 4 other segments by connecting their wire to +24V.
That's like charlieplexing, with only a fraction of the combinations available used. (From what I understand, with 5 wires you could drive 20 independent LED's, but here they only used 8).
How do I perform "charlieplexing" at 24volts? Of course the digital outputs of my Arduino wont' deliver enough current and voltage, so I need some kind of driver that can sink and source current to 5 different points.
Any idea of where I should look?
Thanks a lot!