Ubergeek63
Well-Known Member
glad to help
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I've also heard that the eye responds to peak brightness. so muxing the LEDs with some kind of current feed may save a lot of mA.
Your 40 LED portion doesn't seem to be advanced. I'd suggest you to multiplex them (either in ten consecutive 4-LED sets or in five 2 x 4 LED sets, depending of the desired effect.) This way, your 40 LED will draw (@ 20mA per LED) either 20 or 40 mA.
After reading the application note posted Ubergeek it was obvious that the theme throughout the document was that multiplexing was geared towards saving cost not power. That was why I decided to just forget that idea because the extra work it would have created for me wouldn't have been worth the power savings.
Do you have and ideas about my last questions concerning the capacitor?
I don't see how multiplexing saves power. For example if an LED is powered at 20mA 50% duty cycle it will appear as bright as if it were powered continuously at 10mA.
not that, it means turning one row on for a short time, switching it off and turning on the next one, switching that off and turning on the next one, all really quickly. then you only have one row on at once instead of all 40, which means you wont need as much current at one time. switch between rows fast enough and your eye cant see that they're all not on.