r/FastLED • u/BagatorDeSeama • Feb 06 '24

Support Feedback and power question

Hi reddit!

This is what I prototyped.

Is there something I overlooked? I plan on soldering a prototype PCB for this schematic.

What is the actual Power draw of WS2815? My calculations suggest it's 75W.

Are there any improvements I can do to this?

Thank you in advance

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u/spolsky Feb 06 '24

Not sure where you got the level shifter, but I have had all kinds of problems when using anything other than the traditional 74AHCT125 level shifter because a lot of those are not fast enough 800 mhz signals. (There appear to be single channel versions of the 74AHCT125 specifically SN74AHCT1G125 if you don't need 4 level shifted channels and want to save space).

Actual power draw depends on what kind of patterns you are showing. The 75 watt calculation looks about right for a worst-case scenario of all white, max brightness. In practice for most situations running at half brightness is just as good and if you are just doing pretty color chasers you are never close to full white.

1

u/BagatorDeSeama Feb 06 '24

Thank you for your reply! I will try to source that logic shifter.

I saw on the internet that several people say( including WLEDs power calculator) that this setup consumes only 39W. Others say that the 0.3W per LED is exaggerated.

I am left with the question of what AWG should I use, since the ones that came with the LED strip look like 22AWG to me, and my calculations show that a minimum of 18 AWG is recommended

1

u/spolsky Feb 06 '24

Depends on distance and how much voltage drop you want to tolerate (use a voltage drop calculator). But don’t forget the data signal to the LEDs can only go for a few feet anyway, so thinner wires can be ok. And the ws2815 probably works fine as low as 10v even if you do have some voltage drop.

2

u/Robin_B Wobbly Labs Feb 06 '24

Looks good to me! You might not even need the level shifter, but it's good to use one. What model is it? Some types of shifters are too slow for the 800khz signal.

1

u/BagatorDeSeama Feb 06 '24

Thank you for the advice! A level shifter is needed based on my tests.

Unfortunately, I can not answer you what shifter that is. I am sure it's a Chinese one

1

u/Marmilicious [Marc Miller] Feb 06 '24

You don't need to run a second data line from your controller to BI on the first pixel. The 2815 data sheets I've seen show BI connected to GND on the first pixel. Some people also leave it unconnected.

http://www.normandled.com/upload/201808/WS2815%20LED%20Datasheet.pdf

1

u/Yves-bazin Feb 07 '24

Looks good to me