Author Topic: Powering pixels thru the Cap  (Read 3650 times)

Offline aknflyer

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Re: Powering pixels thru the Cap
« Reply #15 on: March 02, 2017, 12:11:49 AM »
Ray,
I tested a 100 count string of Ray Wu 12v pixels using an all white sequence at 100% brightness, it was drawing 5.9 Amps or 59ma per pixel. I agree with your numbers.

Offline bpos

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Re: Powering pixels thru the Cap
« Reply #16 on: March 02, 2017, 05:13:36 PM »
Ok just for the sake of discussion. I have converted many ican display items over to using LED lamps. All of these LEDs consume 20mA at full on. So with 3 LEDs in each pixel with all 3 turned on full should draw 60mA per pixel. So, from MY past experience I am not real sure were every one is getting these lower figures?  True most often not all pixels are programmed to be white and at 100%. But if you plan on it, then you wont have to worry about any problems.

BTW to my knowledge the only difference between the 5V and 12V pixels is the 12V pixels use resistors to limit the current to 20mA thus dropping the voltage across the LEDs and the WS2811 chip. Current draw should be the same overall. Now I will say that this is book knowledge, I do not own any 5V pixels that I would be able to test myself.
 
Ray

I suppose the draw depends on which type (smd) led your referring to. There are strings and strips with different ws2811 (size/shape) SMD led and different draw.  What is the draw once injected? I was merely talking efficiency and getting the most light (led) on a string without issue.

If you are playing it really safe just use one string per port with power injection.

Offline Ray

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Re: Powering pixels thru the Cap
« Reply #17 on: March 02, 2017, 06:29:17 PM »
Aknflyer, that you for confirming what I have been saying about the 12V pixels. Thanks

Bpos, True I was not saying what LEDs connected to the WS2811 chip. I was thinking that the majority of us use the bullet pixels. But I think my statement if you dont mix apples with oranges (bullets vs strips) is true. There is no current difference between the 5V and 12V pixels. But I am open for correction if someone with a string of 5V bullets would check out the current draw like Aknflyer did, all on at 100% divided by number of pixels.

Offline aknflyer

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Re: Powering pixels thru the Cap
« Reply #18 on: March 03, 2017, 12:00:36 AM »
The best solution is not be limited by the fusing and lower current circuit traces on the circuit board and supply the appropriate power directly to the pixels through a fuse block. You decide how much overhead on your power supplies your willing to go. Most sequences don't average all white 100% very often. The best posts I have seen are from Wolfie, he explains it well. Even has a website explaining it: http://www.wolfiesden.com/diylighting/power-injection-101/
So just tie the data line to the pixels, and connect the pi gnd to your power ground and you can run as many pixels as the board is capable of, providing your power supplies are adequate to your sequence.


 

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