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Neopixel brightness output
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Please be positive and constructive with your questions and comments.

Neopixel brightness output

by njh71700 on Fri Jan 10, 2020 10:26 pm

Hello
So i'm makimg a project using a strip of neopixels and so far its working out well, the only thing is, I need them brighter, I could add more neopixels but that might take away from the look im going for. Are there any neopixel based rgb leds with more lumens or lux or nits or however they are measured? If anyone has info on this please let me know, thank you!

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Re: Neopixel brightness output

by dastels on Fri Jan 10, 2020 10:41 pm

What do you have the brightness set to? The libraries I have used usually have a brightness you can set that's used to scale the RGB values you set.

What language are you using?

Dave

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Re: Neopixel brightness output

by njh71700 on Sat Jan 11, 2020 5:50 pm

Im using python to control the neopixels from an Rpi3. The issue is that only certain pixels are set to have a maximum brightness while most others are set to a lower value to create contrast between the two, so I cannot make anything in the strip brighter than it already is. This is why i'm looking for a strip with an overall higher output of brightness.

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Re: Neopixel brightness output

by bcochran1 on Sat Jan 11, 2020 7:48 pm


Hi,

I haven't really looked into setting the brightness levels of NeoPixels, but I wonder if you are trying to create a sort of persistence-of-vision effect? If so, you may want to switch to using DotStars.

I know that if I use the standard 'strandtest' code for an 8 Neopixel bar, the pixels are very bright indeed, enough so that I look away after a short time. I'm thinking that a set of Pixels running at 100% brightness would be quite enough to make most people look away -- the brightness is rather dazzling. If neighboring pixels were running at a lower brightness level for a contrast effect, this may still not have the result you want, because most people would look away from the brightest pixels.

What NeoPixel strip are you using exactly, and can you share your code? Perhaps post it on GitHub? I don't have a recent Raspberry Pi device, certainly not the Raspberry Pi 3, but I do have plenty of ItsyBitsy devices and a small collection of NeoPixels.

I wonder if your goal is more to do with persistence-of-vision.

Thanks so much

Bob

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Re: Neopixel brightness output

by njh71700 on Sat Jan 11, 2020 8:49 pm

Hi Bob,
The project I am working on is actually a cloud. It's made out of polyester stuffing and has a neopixel ws281 5v waterproof strip running through it. The 'background' if you will lights the whole cloud while the animation I wrote will randomly choose up to 2 pixels to flash at 100% brightness. The background must be bright enough to be visible, but the flashing LED must also be bright enough to stand out from the background. This is why I am interested in a brighter strip, because it would allow the whole thing to operate brighter and still maintain the contrast. I don't have my code with me as it's stored in my Pi at my workshop, but I am certain I have my LED_BRIGHTNESS value set to 255. The problem is, the look I want to achieve is one where the lights diffuse through the polyester, and through that diffusion I loose a whole lot of brightness.

Edit: I'm now thinking the only option is to by a strip with a higher pixel density, but that means more power...

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Re: Neopixel brightness output

by bcochran1 on Sat Jan 11, 2020 9:25 pm

Hi!

That is a very interesting project.

You say you are using a "neopixel ws281 5v waterproof strip..." Is this an Adafruit product? I'm wondering if you really need "waterproof". The casing of the strip may be acting as a strong light diffuser all by itself. Would it be possible to cut the top part of the strip casing off, so that you can expose the Neopixels? That might give you a dramatic change in brightness. Please note that I'm not sure that polyester material is electrically non-conductive. I'm pretty sure doesn't conduct electricity, but you might want to test that first.

You didn't mention what pixel density you are using at this point, but yes, a higher density might help. I also wonder if one or more NeoPixel rings will also give you the brightness you want.

Thanks so much

Bob

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Re: Neopixel brightness output

by njh71700 on Sat Jan 11, 2020 9:51 pm

Did not purchase this from adafruit, beleive it is a third party manufacturer using the adafruit nepixel ic's. The water proof housing contributes negligabley to diffusion, but the thinking is that the casing will keep the polyslester and adhesive spray i'm using off the copper pads to prevent any shorts. My current strip has a density of 50 pixels per meter, and I saw one with 100 pixels per meter that would do the trick, however with 10 meters which I would need, at adafruits reccomended 20mA per led, I would need a 5v 20A psu while injecting power every 1m. Considering I have no formal electrician training, I don't feel comfortable being responsible for that as this peice is an art installation and wouldn't wanna burn down the building....

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Re: Neopixel brightness output

by adafruit_support_bill on Sat Jan 11, 2020 10:27 pm

the animation I wrote will randomly choose up to 2 pixels to flash at 100% brightness. The background must be bright enough to be visible, but the flashing LED must also be bright enough to stand out from the background.

One option is to use regular Neopixels for your background, then use a few super high-power "Pixies" for the random flashes. The Pixies are considerably brighter than the neopixels. And if you only flash them briefly, your average power utilization will not be so huge.
https://www.adafruit.com/product/2741

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Re: Neopixel brightness output

by njh71700 on Sat Jan 11, 2020 10:39 pm

Now this is a very intriguing solution! This would work perfectly as I could scatter these throughout the cloud and still maintain that contrast! The only challenge here is that I would need write 2 different lines of code correct? Or would it be possible to splice these into the data stream at different intervals and power the 3w leds with a separate power rail?

Edit: Answered my own question: They use the uart protocol. Could I write one python script that can output PWM for neopixel and simultaneously output uart to another pin which controls this chain separately?

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Re: Neopixel brightness output

by dastels on Sat Jan 11, 2020 11:02 pm

That shouldn't present a problem.

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