[sdiy] super-nice LED interface ..

[Chris Strellis]

> I suppose a way to ignore ambient light would be to sample 
> the current from
> a detector diode before and during the on-pulse of the 
> adjacent LED, and use
> the difference between the readings.

An astronomer's trick with CCDs!  Dark frame subtraction.

> You might still have trouble with
> changing levels of ambient light.

True. This is always a problem across the field - the real world has infinite headroom - our circuit's world doesn't.  For example digitising audio.

Could try every few seconds, turning all leds off, sampling the "Dark" current, then turning them on again, with the new "frame" to subtract.  Could probably do this fast enough before the eye notices ~10ms.


Slightly different note - remember the Axel Resynthesizer?

http://web.archive.org/web/20040702151000/http://archive.keyboardonline.com/features/vintagegear/vgear0101.shtml 

Cheers

Chris