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Arduino led multiplex7/22/2023 You can't do that and expect brighter LEDs, the problem is that the Arduino output pins cannot supply enough current for all the LEDs. I attached a 5V 2.1A wall wart to V5 in my original 5x5 matrix, but the leLEDs were not appreciably brighter.Ĭorrect. I learnt a lot about leds and power usage the last week. ![]() One more question: if I feed the 5V 2.1A into the usb connector, will that have the same effect as feeding it into the 5V pin? Or will it again go through the Arduino regulator, causing problems there? Now that I can power the leds from the wall wart, I don't have to worry about overheating. Why?Īlternatively I still can make use of my three pcf8574's and dispose of multiplexing. Just to keep myself occupied, I also ordered three MAX7219CNG's, they cost pennies and some of you told me that would be a better choice over the pcf8574. This afternoon I get a new bunch of clear leds and wil resolder the matrix. Anyway, bypassing the 100 Ohm resistors did not change the brightness either. I cannot at this moment experiment with the resistors, because there are green leds and red leds in the same row. Perhaps diffuse leds just are not good enough in daylight. I have 100 Ohm resistors on the rows of the matrix. Green is more or les OK, but Red remains very dim. I attached a 5V 2.1A wall wart to V5 in my original 5x5 matrix, but the leds were not appreciably brighter. My choice would be to us the MAX7219 as it is easy to use and takes care of controlling the LEDs for you you just have to learn how to tell it which LEDs you want lit, then it does the rest for you. The other device, and there are several choices, can also be powered from your 5V power supply. The LEDs must be connected to some other device to both control and power them. You can't connect the LEDs as per your initial schematic because they draw too much current from the Arduino, at least they do if they are to be bright enough to be useful. The power supply can power your Arduino at 5V via the 5V pin, that takes care of the Arduino. The power supply can power you Arduino at 5V via the Vin pin, that takes care of the Arduino. (With thanks to CrossRoads for pointing this out) I suggest you get an external power supply capable of at least 1A at 5V, an old mobile phone charger would be just fine for this. ![]() ![]() So I come back again: how do I power the LEDs from an external power supply.
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