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# What resistors do I need for my complex LED cube? Answered

So I'm working on building a LED cube. But just to be completely different I'm going with a complex design. Overall its a 5x4 with 4 layers, but its not a perfect cube and has only 2 or 3 LEDs per column. I know that I'll need different resistors for the 2 LED and 3 LED columns but how do I calculate what I need from the IC chip to the LED and with the Transistor?
I'm using white LEDs (3.2v @ 20mA) driven by 74HC574 ICs with a 5 volt power supply.
The transistors are 2N2222.

I will do the math if someone can give me the formula or calculator!
(I'm using this a guide http://daid.mine.nu/instructabliss/?url=https://www.instructables.com/id/Led-Cube-8x8x8/)

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## Discussions

Is this a static design (all existing LEDs are on all the time) or do you use a micro controller or any other circuit to scan through the LEDs - any LED is only on for part of the time?

For a static circuit, you can use the led wizard rick mentioned. For a dynamic thing, you can make the current higher / the resistors smaller. E.g. if you plan for 20mA per LED, put the LED is only on a 10th of the time, you can calculate the current for 10*20mA (200mA) or even higher.