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Dec 18, 2008, 04:14 AM
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The war on LEDs

With the next 50 paychecks slowly creeping their way down from the Land of Layoffs, U get more angle sensing.

So the optimum configuration uses the brightest red LED possible with the narrowest angle & the LED's base 1.5" above the mirror. The centers of the LED & photodiode R .5" apart. The mirror is 3/8" long & as wide as we expect the key to be. Surrounding area is blacked out.

This gives a 25mV swing through the key's motion. The light travels just the length of the photodiode as the key moves.

U must be able to move the sensor sideways to adjust it & get the mirror position to line up with the edge of the photodiode. Also need to block light from adjacent keys & fit it all in the width of a key 88 times. U better get started.

Even if the current sensor worked, it's no guarantee the fully assembled 88 sensors would be even enough. Still not sure how we're going to bias the up & down positions. There seems to be quite a lot of drift with it.
Last edited by Jack Crossfire; Dec 18, 2008 at 04:27 AM.
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Dec 18, 2008, 08:44 AM
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