11x10 adressable LED Grid

I would like to build a device which needs a 11x10 LED Grid. I need to be able to adress every single LED individually. What do I need to build this?
I didn't find any board/matrix kind of thing that actually has the dimensions 11x10. So I think I'll have to go with LED strips instead, right? I was thinking about using Adafruit NeoPixel Strips. As far as I understand them, they can be adressed individually and can be cut into single LEDs so It would be easy to arrange them into a 11x10 grid. However, I would need 110 LEDs so that means I would need 4 meter of the strip which costs 67$. I feel like that is quite expensive and I don't really need it. For example the NeoPixel strips are waterproof which is irrelevant for my application. I searched for some other strips and found some alternatives, but they are usually only cutable every 3 LEDS. That's not good for me, since neither 10 nor 11 is dividable by 3. Is there any good and maybe cheaper alternative to the NeoPixel strips?

NeoPixels are Adafruits version of generic WS8212 leds. You can find cheaper on Amazon or elsewhere. You will also need a beefy power supply to power them all.

To build it, cut 10 sections of 11 LEDS and then wire them up. Using a serpentine pattern takes less wire, but more code depending on what you intent to display.

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I've run as many as 256 NeoPixels directly from a Nano. However, the brightness of each LED was drastically reduced in order to keep the power consumption tiny.

You didn't say, if they have to be RGB.

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Generally the 12 volt strips have the LEDs in groups of 3, and the 5 volt strips are individual LEDs. The strips come in different number of LEDs per meter, you may be able to find a strip with a convenient spacing for your project.

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Also if you are flexible about the spacing, you don't need to cut the strip to make an array. Just fold the strip into a zig zag arrangement.

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Ah cool, didn't know that. What do you mean by "beefy"? I was planning on using some standard 5V/12V power supply. Is that not enough? Or you just wanted to say, that I can't just connect them to the Arduino itself?

I think in my project it's not even gonna take more code. Depends on how readable I want the code to be, I guess.

True. I didn't, because I haven't decided yet :smiley: Technically, I only need white ones, but I'm considering to use RGB ones anyway, so that I still have the option to change color, if I feel like it at some point.

That's also great information, thanks. Is there a reason for this, or did they just happen to become standard like this?

I'm not really flexible. Or rather, I am flexible about the spacing, but in the end the grid has to be equally spaced in both dimension. Nevertheless it's interesting to know, that the strips are flexible enough to be folded in a zig zag pattern. I didn't expect that.

Yes, the 3 LEDs are grouped that way because they are current driven, and this allows the least power dissipation (and thus power waste) in the limiting resistor.

110 LEDS x 60mA per LED (full power) = 6.6 A. That is "beefy" compared to a standard phone charger that delivers 1-2A

That is because it is such an odd dimension. :crazy_face: However we have seen that dimension mentioned previously here, so perhaps you should explain the purpose?

Suffice to say that if you only want a monochrome matrix, and do not want it as shockingly bright (visible in full sunlight) as the NeoPixel/ WS2812s, then just two MAX7219 module would drive a 10 by 11 matrix perfectly well drawing 650 mA - but it would not be wired as a neat 10 by 11. In any case, that is just a matter of coding, as it is for the WS2812 strips.

See your point.

Sure, I wasn't surprised I couldn't find it in such dimensions. In the beginning I thought there might be manufacturers who let you choose the dimensions, but that doesn't seem to be a thing. I want to build a word clock like QlockTwo.

I'm not worried about wiring and coding, that won't be a problem. About the brightness: It should definitely be possible to see it very clearly in the middle of the day. Not in direct sunlight, but when the room is illuminated by a lot of sun light. And also from a quick amazon search it seems to me, that MAX7219 only come in one specific spacing, right?

Use discrete white LEDs driven by TPIC6B595 shift registers. Connect an entire word to a single output of the shift register (outputs are open drain, and can drive up to 50 volts / 150mA each). Brightness can be controlled using a PWM signal into the output enable pin.

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I think the idea was to use the IC to make your own wiring...


OK, the "word clock" - that makes sense and probably is the reason for the particular dimension which I do seem to recall being asked previously as it is a"standard" design. What was used in the article(s) you saw?

Well, I can see a value in a polychromatic display but the MAX7219 should provide quite adequate brightness for a monochrome indoor display.

That certainly might suit some designs, but not all as I understand it. :grin:

You are presuming connecting multiple LEDs in series and powering from 12 V (three or four in series) or more.

Actually, not all LED positions would necessarily be populated.

I don't use Amazon - I am too cheap (by a long shot)! :grin:

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They didn't mention it, but where rather broad on the subject.

I'm not aware of any cheaper option. As long as you don't want to purchase hundreds of the same part, I've never seen anything cheaper. Can you recommend anything? Prefereably something available in the EU.

How would that work. Looking at this it seems like the TPIC6B595 has only eight outputs. But I would have a lot more than eight words. Or are you suggesting to use multiple of these shift registers? What would be the advantage of this solution to using LED strips? Is it cheaper?

You can Charlieplex 110 LEDs with 11 data pins.

That might be the least expensive solution. Eleven resistors and 110 white LEDs, driven directly from an Arduino Nano.

I just found a WS2812B Strip for less than 6€ per meter for the none-waterproof ones on ebay: 5V WS2812B RGB 5050 LED Streifen Strip Lichtleiste Individuell Adressierbar 1-5m | eBay . That would be quite a cheap option. Do you think this is a good and safe option or would you not recommend something like this?

I don't know about that particular one, but I've bought about 10 similar ones and never had any problem. Note, they're available in different spacings - seems useful for your application.

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Yes, that's what I wanted to know, thank you.

Yes, I saw. I'll probably get 4 meters of 30 LEDs/m. And those 4 meters will still be cheaper than one meter from Adafruit.

You can also find 60 LEDS/m but those are usually more expensive since you buy by the meter and you are getting twice as many LEDs. Depends on what your application needs...

Yes sure, but 30 LEDs/m is a way better fit for my project in terms of spacing. Of course I could also get 60 LEDs/m, which is a little cheaper, but then I would definitely have to cut and rewire every single one of them. In this case, I think, I prefer to pay a little bit more and have them in a spacing which already suits my project.