Re: 19,008 LEDs on the wall, 19,008 LEDs

["Michael J. Mahon" <mjmahon@aol.com>]

logjam wrote:
> I'm only going to be driving about 900-1800 LEDs at once, and at around
> 50-80ma a piece (pulsed rating)
>
> So we're looking at around 180A.  You're pretty close.

Of course you are multiplexing them--that's why I said "average".

> I found a 150A 5v supply for $70.
>
> The voltage drop on the resistors was about 1v.  So that's a good 150
> watts of heat.  :)

I figured about 2.5v across the LED, plus 2 times .6v for the row and
column transistors, which would leave about 1.3 volts for a current
limiting resistor.

Eric's idea to use a constant-current switching supply is a good
energy conserving approach, but there are issues with balancing
the current to 900-1800 LEDs at the same time, and I'm pretty
sure that you aren't going to want to drive them in series!  ;-)

-michael

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