I have this living room floor lamp with 2 x 1.50m warm white LED (about 100/m) under a silicone diffuser (photo below).
I would like to convert it to adressable and sound reactive with a Pixelblaze I have on hand.
But I’m not so sure about which LED to put inside:
I have WS2812 RGB 144led/m on my hands and even when I put it to white, it’s not as bright as these “dumb” white LED (I’d like to keep at least the same luminosity when it’s in white mode)
I see a little bit the “pixels” under the diffuser at 100 led/m at the moment and wouldn’t want to go lower than this in terms of density. 144 will be fine.
I looked at Cob LEDwhich look perfect due to the 720 LED/m high density (like these on AE) and the 12/24V that will allow me to reduce cables size but these don’t seem to include RGBW so I’m not so sure about luminosity. Also these Cob are not individually adressable which means i will probably have a better resolution for “dot” effects with 144 LED/m.
Else it seems a solution would be to use SK6812 RGBWW 144 pixels/m (I can’t find a 12V strip with this density AND white LED).
So I have questions:
when I request white on a RGBWW, does it light up the white LED (obviously much brighter than the color ones) AND the RGB ones ? Does it do good luminosity from your experience compared to WS2812 for example ?
should I be worried about power drops in 5V over 1.5M considering I want to be able to reach max white luminosity ? I have limited space to run big cables (seems i’d need up to 12A in 5V) in the horizontal tubes that connect to the “central tube” and i can use only one of these per 1.5M.
For any kind of illumination project, RGBW LEDs will give you a much better white while taking less power.
Pixelblaze does not currently use RGB when making a pure white on RGBW LEDs, instead relying on the white element. While it’s technically possible to drive R+G+B+W at the same time, the color output suffers and negates some of the benefit of having a white element in the first place.
The RGB elements can help balance the color temperature, but when used for white creates 3 distinct spikes on the spectrum, whereas white LEDs tend to have a more even spread across the spectrum. You can see that here in this graph from a datasheet for an RGBW LED that is available with 3 white temperatures (warm, natural, and bright):
Take for example the light around 550nm, there’s virtually no light emitted at this wavelength with RGB, and natural colors in this zone would appear dark if illuminated with R+G+B light.
There are also addressable LEDs with 3 different white elements, allowing you to mix a range of white color temperatures. While pixelblaze doesn’t support rendering to that color space, it’s still technically possible to drive them like they were an RGB LED.
I would recommend either increasing the number of RGBW LEDs until you reach your desired white brightness, or mix in another white source to provide the bulk of the illumination. There are addressable drivers that can drive dumb analog LED strips as if they were a single pixel, and that could be mixed in with other addressables.
For power, most 5V 144/m strips will be fine over 1M. Working in confined spaces could cause heat issues, and 1.5M might work in some environments but have issues in others. There are a lot of variables!
Thank you @wizard , super clear and detailed as usual.
So even though I find Cobb LED “brighter overall” than RGBW 5050, using the 5050 RGBW will give a me better quality white.
I think I will have to go with that but damn, 40W/m in 5V = 60W for 1.5m. I will never have enough space to get wires thick enough…
Seems I’m stuck: I need over 100 LED/m in RGBW adressable but none of these exist in 12/24V… Will need more research…
On the topic of “white”, I have a strip of White-Warm-Amber LEDs which I map to B-G-R in PB so that I can reason about the “color temperature”. It’s nice to be able to mix these 3 whites for room illumination. Animated patterns are fun too!
Not only a wiring problem - a bigger issue might be the amount of heat that you’d need to get out without the LEDs cooking. Also, that would be extremely bright - you’d probably be fine with less than 20% of that unless you’re lighting things up in broad daylight. One of the things that I really like about the Pixelblaze platform is the way that a maximum brightness can be set while still allowing your code and the brightness slider to have a full range of control. Setting the brightness limit at a much lower level can save a few problems and can also help to lower cost in the power supply department.
It’s true, it might actually be way more than I need.
Nevertheless, I ordered AWG18 which should be enough, and I found a 150W power supply., might be ok.
In terms of heat, we’ll see but it’s an aluminium frame .
