Double the output, ( or viewing angle ) , same current , half work for a MAX7219

I have tried a search on this subject, but quite honestly the forum is so big now, that it takes ages to sift through the threads bought up. This might be old hash .

Let me just run this past you guys....

I made a soccer scoreboard with 7x5 displays last year , Using the SAA1064 chip , which gave a 50% duty cycle , for max output from each LED. I am now making some more boards using the MAX7219 driver.

I have arranged it this time with 5 columns across and 7 high .

This means I can set up in the register to limit to 5 columns, and skip the other 3, giving more brightness , 20 % duty cycle, but still down on the 50% duty cycle of last years

The LEDs I am using this year are more than twice the output of last years ones, so I should be back on track with the actual apparent brightness of last years project.

Now I have a request for a similar sign twice the digit size ( 4 times the area ) but I have realised that I can put 2 red LEDS in series in place of the previous one ( each has 1v9 voltage drop ) and the chip should be able to supply Imax to both LEDs in series at 3v9

So in theory I can get twice the light output per column, using twice the number of LEDs, with the chip now running cooler, as it doesn't have to get rid of the extra ( 5 - 1.9 v )

But since now I am saving the power dissipation in the chip, perhaps I can pulse the LEDs with twice the current as before ? Giving me twice the light output for the same digit ? ( OK at double the supply current, but there is no such thing as a free meal ! )

How does this sound ?

If you are not upsizing, you could tilt every other LED by half the viewing angle and get the same intensity as with one LED.

Sounds good to me. I made some large 7 segment displays with 2 LEDs in series in each segment. Work great.

Are you up to this size yet 8) ? http://www.vegasledscreens.com/products/stadium-screens-sports-displays/sport-perimeter-led-displays.html

have you tried 3 LEDS in a triangle to replace 1 original LED? 3 x 1.9V = 5.7 Volt ? might be just within the operational margins...

Also consider a Fresnel lens on top of the LED to bundle the light.

Others had that idea too - http://link.springer.com/article/10.1007%2Fs12541-009-0038-8#page-1 -

Or perhaps just go to a larger LED, 8 & 10mm seem pretty available. http://www.mpja.com/Super-Bright-LEDs/products/440/ 100,000mCD!

Maybe 2 in series, 2 in parallel at each location of the LEDs you already have. Keep MAX7219 current under 40mA, so 20 mA/pair. Going to need to cool the MAX7219s. Big AL plate over them with heat sinl compound to ensure heat conduction.