----- Original Message -----
From: "David Strickland" <stricnine@NEO.TAMU.EDU>

| I'm working on a clock design using some LEDs, and have no real idea
| what range of mcd (milli-candela) I need to use for it to be visible
| during the day.
|
| The 7-segment and matrix setups I looked at so far ranged from 4.8 mcd
| for a green 5x7 matrix, to 8 for a green 7segment, to 20 for a red 7
| segment.  Are these remotely bright enough to see across a sunlit room?

Depends largely on where you live. In the Western U.S --> Nope.
In boggy ol' England --> probably so.

I've used some 50 mcd LED's that are pretty visible outdoors here in
Colorado, if you overdrive them by about 50-75%... probably not a good idea
for a clock, since you'll end up burning them out.
My best advice is to experiment. See what works for your particular
circumstances/conditions.

- Robert :O)

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