which 8x8 green dot matrix LED to buy?

I am looking to build a scrolling text project using some 8x8 dot matrix LEDs. I want bright green LEDs like https://www.youtube.com/watch?feature=player_detailpage&v=9uZZjuBiZLA#t=32. Anyone have any recommendations?

If your using the MAX7219 as the driver chip like the video seems to do then make sure the matrix is 'common cathode'. They come in different sizes (60x60mm, 38x38mm and maybe others) so pick your size and maybe also get the backboards that contain the MAX7219 and extra components, this will save a lot of wires.

Google "parola" http://forum.arduino.cc/index.php?topic=171056.0

https://www.youtube.com/watch?v=JgzVCSFaz3I&feature=youtu.be

http://parola.codeplex.com/

check www.kingbrightusa.com, www.futurlec.com for displays.
Check the “Luminous Intensity”
Make sure you compare mcd vs ucd (1000ucd = 1 mcd) and the current need to achieve that (10mA vs 20mA for example).

Common cathode vs common anode - with 8x8 matrix there is no difference, just the orientation of the part.
Common cathode - the driver will source current into 8 anodes, and sink from 1 cathode at a time.
Common anode - the driver will sink current from the same 8 cathodes at 1 time, but only source current to 1 anode.
Net effect: 1 row, or 1 column is turned on - rotate the part 90 degrees, and you can’t tell which is which. But the display you want, then do a little experimenting so you can tell which corner is which when you light up anode0, cathode 0 vs anode 7, cathode 7.

Thanks for the helpful information and the links.

I am thinking of buying unassembled MAX7219 modules, so that I have the option to put the ICs on a breadboard and arrange the displays as I want.

http://www.ebay.com/itm/MAX7219-Red-Dot-matrix-module-MCU-control-Display-module-DIY-Kit-for-Arduino-/400373211698?pt=LH_DefaultDomain_0&hash=item5d381a6232

Those aren't green. ??

CrossRoads: Those aren't green. ??

No they are not green. I didn't find any MAX7219 module with green LED. I found some green 8x8 LED at one of the sites you linked and they are very cheap. http://www.futurlec.com/LED/LEDM88Gpr.shtml

I think I will get these green 8x8 LEDs and swap them with the one's that comes with the modules, it should work :)

I have read somewhere that the chinese copy MAX7219 doesn't work properly if they are chained more than 5 or so. I need the board so I think I will get them anyway. I will try them and if necessary replace them with original MAX7219.

ruleworld: I found some green 8x8 LED at one of the sites you linked and they are very cheap. http://www.futurlec.com/LED/LEDM88Gpr.shtml

They might be, if it were not for postage. :astonished:

Paul__B:

ruleworld: I found some green 8x8 LED at one of the sites you linked and they are very cheap. http://www.futurlec.com/LED/LEDM88Gpr.shtml

They might be, if it were not for postage. :astonished:

postage(standard post) is $4 for orders up to $29, which doesn't seem very high 8) http://www.futurlec.com/Delivery.shtml

•3mm Dot Size - 32mm x 32mm overall. 1 1/4" x 1 1/4". Small size ok?

CrossRoads: •3mm Dot Size - 32mm x 32mm overall. 1 1/4" x 1 1/4". Small size ok?

Ah I didn't see that. I think I need 6cm x 6cm overall size. I have to look again. Thanks for pointing it out!