Charlieplexing & LED leakage

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faisal78

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Hello
I am designing a charlieplexing LED drive scheme using an Arduino board.

Connection are something similar to the above.

LED1/2/3/4 are all RED LEDs with a Vf of ~2v.
LED 5/6 are BLUE LEDs with a VF of 3.6v.
All LED source is driven from 5V supply.

In theory, when I am driving LED5 to be turned ON, there should also be a leakage path through LED1/3 because the Vf of the RED LEDs are so low.
Can anybody confirm this?
FOr some odd reason, I am unable to replicate this symptom on my board and was working if that my setup/configuration was wrong.
Any help/clues?

Thanks in advance.
 



Hello, another great example of the possible leakage issue can also be seen in the below application, which I have taken from
https://fritzing.org/projects/charlieplex-snowfallshooting-star-20-leds

Same scenario, when trying to intentionally turn on LED04, the anode (green) would be ~5v, and cathode (blue) would be ~ground.
There is a possibility of a leakage path via LED03 and LED10 which I had marked out the path on the diagram.

 

LED1/2/3/4 are all RED LEDs with a Vf of ~2v.
LED 5/6 are BLUE LEDs with a VF of 3.6v.
Click to expand...
The worst of all possible combinations, can't work without unwanted lighting of red LEDs.
 

FvM said:
The worst of all possible combinations, can't work without unwanted lighting of red LEDs.
Click to expand...

Hmmm, is there really no solution to Charlieplexing a RGB LED from a single power source?
 

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