On February 22, 2006 11:45 pm, Peter Todd wrote:
> Anyone have any experience with this? I just started a project that
> will be a cube with 6 led matrix displays, one on each side, using
> 5x7 led modules. Each side will end up as a 35x35 matrix that will
> then display a 3d rendered wireframe image of a cube.

That's only 7350 LEDs.
Maybe you should add another LED to indicate you have power to your 
circuit in case someone needs reassurance the circuit is turned on ;-)

> The modules I got, the cheapest I could find, have 100ma peak
> currents and 11ma average current ratings. So... I was going to base
> my design around simple ULN200x and UDN200x source and sink drivers
> with 74hc574's to drive them. The drivers can do 500ma source or sink
> so that should be fine.
>
> One challenge I see is power. Peak power, for all leds on, is about
> 16 amps per side! Or about 100amps for the whole board! That's just
> nuts... Is there such a thing as a simple, self-contained switching
> regulator that can handle a decent amount of current? I'd like
> something as simple as a 3-pin regulator, no external components or
> anything. I'm trying to have this thing completely built by March
> 11th, which I know is utterly insane, but trying is fun!

You can try reducing current by stacking the voltage planes. 6 boards... 
that would be 100amps/6 = 17amps.
Divide by 4 and you are needing 4amps x 24 layers, or 120vdc to power 
your tower of 5v x 24layers.

One set of boards driving your LEDs etc runs at 0-5v,
Another set runs on the 5-10v layer,
Another set runs on the 10-15v layer,
Another set runs on the 15-20v layer.....

Another thing is, if you are running identical pictures on each side, 
then you can also reduce the circuitry by 6 by putting 6 LEDs in series 
controlled per driver. You'll need a different driver most likely since 
you'll be needing a higher voltage.
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist