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Author Topic: RGB LED Matrix spread over 400 square feet (43 square meters)  (Read 1919 times)
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I have very little knowledge about electronics, so I'm posting here for help about feasibility both in technical terms and ease of manufacture.

Ideally, I would need an RGD LED Matrix, something like this: http://www.adafruit.com/products/607  but spread over a big area, more or less 400 square feet (40 square meters). I would need each LED about 8 inches (20 cm) apart from each other and several feet of leeway on the back, between the actual LED and the circuit board. At least 15 feet (5 meters) between LED and board.

As a test, is it possible to take something like this: https://www.adafruit.com/products/274 and then "detach" the LEDs and 
use some sort of cable, solder that to the board and then connect the LED at the end of the cable?
So for each LED it would be circuit board -> length of cable -> LED.

I don't need to display any kind of animation, just on/off and color (just for the final RGB board) for each LED or a group of LEDs.

I would also need some distance, probably another 15 - 20 feet (about 8 meters), between the circuit board and the computer controlling the matrix. I'm not sure if it would be easier or better for this distance to be between the board and the controller or the controller and the computer.

Finally I would also appreciate any help with the "shopping list" involving the project. I suppose I need the matrix and an Arduino or a similar controller, but besides that I'm not sure about power sources, cables, etc...

Thanks in advance for your help
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help about feasibility both in technical terms and ease of manufacture.
Very hard on both counts.

Quote
just on/off and color (just for the final RGB board)
When you say colour are you talking about just primary and secondary colours or do you need more.

Multiplexing and fading LEDs require high speed signals and these are "absorbed" by long cable runs.

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then "detach" the LEDs and
use some sort of cable, solder that to the board and then connect the LED at the end of the cable?
Yes that would be a good idea, but you have to drive the LED like you would in the final design to get an idea of if it would work. I strongly suspect that it would not work.

You might want to look at distributing the driving with something like this but this many will not be cheap.
http://thingm.com/products/blinkm/quick-start-guide.html
« Last Edit: January 29, 2013, 12:13:55 am by Grumpy_Mike » Logged

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About the colors, let's say: red, green, blue, orange, white and yellow
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About the colors, let's say: red, green, blue, orange, white and yellow
As orange is not a primary colour it involves having red full on but green only half on you are talking about fading the LED and that is almost imposable over the distances you talked of. So you need to distribute the drivers, even then you have difficulty talking to them over such distances.
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(40 / 0.2)^2 = 40,000 LED's * 3 channels = 120,000 channels. On it's own that's a lot of things to control, a lot of things to wire up, a lot of things to solder, a lot of things to buy. Buy you must do all of those things for each LED.

It took me hours to wire up 15 RGB LEDs in strands like Christmas lights. Each lead: cut, strip, tin, clip, align, solder, insulate, test.... 40,000 may take a lifetime.

Edit:
Whoops i misread, but that still comes out to something like 900 LEDs. Not so out there, but we are still talking about weeks or months of work just to wire them together.
« Last Edit: January 29, 2013, 04:08:44 am by stoopkid » Logged

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You might get away with using a main control, intelligent sub-modules and WIFI communications.
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If you have enough money, you can use digital pots to fade the leds.
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It's about 1000 RGB LEDS or the equvivalent of 3000 individual LEDs (20 cm apart = 25 pr/m2).

But that is still a very large amount of LED's to control individually.

I would do as GoForSmoke suggests, create a modular design with a local controller for say each squaremeter controlling 25 (75) LED's, then hook up all the local controllers somehow to a "central intelligence unit".

There are lots of potential trouble spots, including power supply and method of controlling 40 individual modules.
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I have that as about 1000 LEDs

(6.3M per side * 5 leds per M)  Squared

[edit]
Not a very high resolution BTW - How far are you viewing from?

did you see the Olympic stadium light show? Now that was cool, all those paddles....
[/edit]

« Last Edit: January 29, 2013, 04:27:46 am by 0AlphaOmega » Logged

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Actually it's not meant to display any kind of animation. Just on/off for each individual LED or on/off for a group of LEDs.

I thought about LEDs at first, but is there some other light source/bulb type with which I can get different colors (white, blue, green, red, orange, yellow)? Maybe something simpler to implement?

Would it be easier with just red, green, blue? How about one color?

What I need is basically a grid with light sources, with individual addressable points, controlled by a computer. The ability to use different colors would be a big plus.
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What would be the viewing distance and viewing angle or in other words would the LED panel be installed vertically ?
What are the viewing environment be dark and indoors or outside in bright daylight ?

The above at a minimum will determine what output your light sources will need to generate.

Given the size of the project one could easily assume that you won't get away with small 20mA LEDs but need something that has more light output. Of course your project is technically feasible. That is really not the question!

The question really is what are your time and budget constraints ?
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What sort of power are you expecting each LED 'pixel' to have? From the physical size I guess that these will be viewed from a long way away and would need a considerable amount of power for those tiny specs of light to be visible.
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Would it be easier with just red, green, blue? How about one color
I told you before primary and secondary colours are easy.
Red, Green, Blue are the additive primary colours,
Yellow, Cyan, Magenta are the additive secondary colours. All involve just on and off with no dimming.
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Don't forget white (all on) and black (all off).
But as long as you're doing it, PWM is high speed on/off with controlled time for each -- you can make any apparent color you want.

Why RGB leds when you can get high power red, green and blue leds cheaper and cluster them in 3's? Same number of connects but each with its own heat sink. much more practical.

As to module intelligence, stand-alone AVR chips are far cheaper than a full board per unit. You will need power and ground commons at least 12V with such wire lengths and leds not so far from any one controller that low V signals affect your lights. You don't have to use radio, it would easier is all, bluetooth modules can be found for less than $10 each nowadays. For something with 1000 -bright- points of RGB you will be spending a good bit anyway so you might as well get it right.


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What would be the viewing distance and viewing angle or in other words would the LED panel be installed vertically ?
What are the viewing environment be dark and indoors or outside in bright daylight ?

It's a vertical installation, indoors with lights on. The viewing distance should be short, in the 6 feet (2 meters) range.

The thing is I can't rig the whole thing from scratch. I just don't have the knowledge, so I thought there might be a way to modify something already on the market, like the links I provided at the top. Time is not an issue, but this is a personal project and definitely I am not willing to spend thousands of dollars.

To maybe provide a better picture, imagine one of those old maps used to learn geography that had light bulbs on each state or country. A bulb comes on and you have to identify the location.

I need something similar, ideally with colors, and I thought it would be easier to control with a computer, as I would need to input individual addresses or a group of them, let's say I can turn on/off B23 or turn on/off B23, D18, G8, J15, A2. 
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