AVR-Chat

I thought I might chime in here re LED brightness:
The newer "ultra" bright LEDs, in the 3-7000 mcd range
and can be seen in most daylight conditions when placed
in a dark background or hooded arrangement.  They are still
moderately expensive for the very good ones, about a buck for
green, blue, or white.  Red and yellow LEDs have been very bright
and cheap for some time.  There are no common bi-colors of the
ultras, as yet, and the old red-green are very poor, the green half
is usually dim and yellowish.

Ken


David D. Rea wrote:
>>LED's are in use at the moment, but useless under nominal lighting
>>conditions. Bright daylight.
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> There are a variety of very bright daylight-visible LEDs on the market.
> Some output hundreds of mcd in only tens of milliamps. 
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> Consider this option - arrange six high output bi-color (red-green) LEDs
> in a line. Use the PWM capability of the MSP430 to drive each of them.
> As the indicator "rises", first the LED begins to glow green, then
> becomes a brighter green, then the PWM begins to int   roducered.Asmore
> red is proportionally added, the color changes from green to yellowish.
> At 50/50, the LED appears yellow. Then, as the indication continues to
> rise, the light begins to appear       moreandmoreorange,thenred.
> 
> This would have sort of a "VU meter effect" and would be very good for
> at-a-glance readings. All functionality could be achieved on-chip.
> 
> A quick Digi-Key search returns a high-output red/green LED in a 5mm
> case, the Lite-On LTL-293SJW. It outputs 90mcd red, 40mcd green -
> intensity will look about the same due to varying spectral sensitivity
> of the eye when both are run at 20mA. They are $0.37 each and there are
> thousands in stock - might as well pick up a few and try them. At that
> price, even if it doesn't work, it's not much invested!
> 
> Dave
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> Yahoo! Groups Links
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