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Topic: RGB LED Matrix: Circles or Squares? (Read 3440 times) previous topic - next topic

geogecko

Of course, looking at the Colorduino, I stumbled across their RGB LED Matrix, in both circles and squares.

Any idea which would be better for a clock (32x8)?  I think the squares actually looks kind of cool, but I don't know if this would look weird, and the circles be better?

Does text look better with one over the other?

Secondly, in a lot of the pictures of these things, it looks like you can see the individual LEDs behind the diffusion material.  Is this just due to decreasing the exposure of the picture, so that everything isn't blown out, or can you actually see the individual LEDs when they are on?

aalex_arduino

Square would be better for this application. IN Colorduino.

aalex_arduino

Quote
Secondly, in a lot of the pictures of these things, it looks like you can see the individual LEDs behind the diffusion material.  Is this just due to decreasing the exposure of the picture, so that everything isn't blown out, or can you actually see the individual LEDs when they are on?

I didnt get you! can u please elaborate more?

buzzdavidson

There is a huge range of quality with the available LED matrixes.  I've got several different kinds, including the square ones you mentioned.  They are pretty nice, kind of middle-of-the-road, and it's hard to beat the price.

I've got a couple of cheapo ebay modules that are downright terrible, flimsy things.  The colors are often inconsistent within a single display.  The units that SparkFun sells are quite nice, with a very effective diffuser that makes the colors appear much richer and better blended; I've ordered a few at different times and they are quite consistent in their color representation.

Some of the cheaper units either have lousy diffusers or none at all; in some cases you can see the individual red, green, and blue elements in each LED/cell.


geogecko

I was kind of concerned with the huge range of prices of these things.  Anywhere from $15 to $30, and probably cheaper on eBay.

I notice that Sparkfun does not carry the square ones, and it seems like they are always out of stock of the round ones.

Do you think the quality of the units from iteadstudio are good?

Consistency of the colors on different batches of units is important to me, because while I plan on using 4 of these, I only plan on buying one right now, until I get more comfortable with it, and get my code up and running, then I will buy the remaining 3.

aalex, what I was referring to was the individual chip LED's that are used for each dot in the matrix.  They use 3 LED's per dot, instead of an actual RGB LED per dot.  The picture at the bottom of this link is what I'm talking about.

http://iteadstudio.com/store/index.php?main_page=product_info&cPath=35_37&products_id=190

buzzdavidson

As I said earlier, I'd rate the iTead studio units to be merely satisfactory.  Ultimately you'll need to order a few types and draw your own conclusions.  The iTead units are much, much thinner than those from other manufacturers.  I've got 4 of the square-pixel units; the rigid portion of the LED frame is so thin that it is subject to warping (presumably during manufacturing).  Two of my displays are noticeably curled.  Colors are OK, but nowhere near as saturated or consistent as the displays I've gotten from Sparkfun. 

I've been playing with these little r/g matrixes from ebay lately: http://goo.gl/bK8NU. $12.99 for 10 with free shipping. I'm building a neat little modular display with the things; unlike most of the 8x8 matrixes that I've seen, these are 38mm square. 

geogecko

Hmm...well, for this project, I'd like all the components to be of high quality.  This is something that will probably be used for several years in our living room (we got rid of our cable DVR, and instead, record TV over-the-air via a network tuner and PC, and then stream it to the living room with an extender.  The problem this presented, is that we didn't realize how much we looked at the clock on the DVR.  That is where this project comes in.  I could just make a simple 7-segment clock, but what fun would that be?

I guess I will opt for the SparkFun matrices, based on what I've read here, and elsewhere, provided I can still get them (backorder?).

Wow, I cannot believe the price on those R/G units, basically $1.29 each!  For that kind of price, they would be fun to play around with.  Are you making your own drivers, I presume?

I remember when I first started thinking about this project about 5-6 years ago, and those RGB matrices were over $50 each, so I guess they have come down quite a bit, even for the good ones.

buzzdavidson


I guess I will opt for the SparkFun matrices, based on what I've read here, and elsewhere, provided I can still get them (backorder?).


To risk being insanely obvious, one could always track down other sellers based upon the datasheet.  I do love SparkFun, but when they run out of something it seems to take forever for them to re-stock.


Wow, I cannot believe the price on those R/G units, basically $1.29 each!  For that kind of price, they would be fun to play around with.  Are you making your own drivers, I presume?


I know, right?  I did a double-take when I first saw the listing.  BTW, the seller apparently has a warehouse full of the things and does provide a larger price break for larger quantities.  I've got 40 on hand right now and want more :)

Yes, I'm making my own driver for the things.  It's a 2D modular design that allows you to build arbitrarily large bicolor displays, supports hot-plugging and individually powered nodes. Four bit per color PWM - you can actually generate a LOT of interesting colors with a bi-color display (as long as it doesn't involve blue<g>).  All kinds of interesting game/interaction possibilities with this one.  Waiting for my first panel of 4-layer boards from DorkbotPDX... I'll post a message here when I have something tangible to show.

geogecko

I did try and find another supplier, but unfortunately, SparkFun is the only US supplier I can find.  I did find a web site where a couple guys had made a weather station, using one of these as the display, claiming that he got it for $12 (site was copyrighted in 2009), and he lists the SparkFun datasheet.  Unfortunately, there is no contact information on his site.  (http://goo.gl/YKWzG)

$12 would be a steal!

I never even thought about using an R/G display to make more than two colors, but that makes sense, since they are basically just missing the blue LED.  Just mixing different intensity levels of each color would give you an interesting range of colors.

Would love to see what you have come up with, when you get time.

geogecko

After a little digging on eBay, I was able to locate another company that sells what looks like identical RGB matrix modules as the Sparkfun ones.

http://www.geeetech.com/index.php?main_page=product_info&cPath=15_38&products_id=145

The datasheet shows their particular company, but the part number matches the Sparkfun YSM part number.  And they are only $20, and on top of that, they are in stock...

Looks like I'll be buying these!

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