jdc@rama.UUCP (James D. Cronin) (11/30/90)
The current Radio Sh--- catalog lists high brightness red LEDs for $4.95. Who makes these? Do any of you know where they can be procured for less than $4.95 each? Also, are these the last word in LED brightness? Is there anything brighter? Thanks...Jim Cronin jdc@rama.sc.harris.com
scott@hpcvca.CV.HP.COM (Scott Linn) (12/04/90)
/ hpcvca:sci.electronics / jdc@rama.UUCP (James D. Cronin) / 11:18 am Nov 29, 1990 / >The current Radio Sh--- catalog lists high brightness red LEDs for >$4.95. Who makes these? Do any of you know where they can be >procured for less than $4.95 each? No. >Also, are these the last word in LED brightness? Is there anything >brighter? HP makes ones up to 5 times brighter (25 Candela). They are around $12. Scott Linn
scott@hpcvca.CV.HP.COM (Scott Linn) (12/05/90)
/ hpcvca:sci.electronics / scott@hpcvca.CV.HP.COM (Scott Linn) / 3:22 pm Dec 3, 1990 /
>HP makes ones up to 5 times brighter (25 Candela). They are around $12.
I made a mistake. The HP leds are min. 8 candela, typically 15
candela, and maximum 36 candela (all at 20mA).
By the way, if you are going to use an led in something like a
flashlight, you would be better off not looking at the strict candela
number, because most of the high-brightness leds have an extremely
small angle of light output (typically <= 4.5 degrees). A
high-brightness, wide-angle led would be better for this application.
Scott Linnnagle@well.sf.ca.us (John Nagle) (12/08/90)
What's the output wavelength on these things, and how stable is it?
Is it narrow and stable enough that you can use an interference filter
to block other light sources at a detector?
On interference filters: the passband changes with the off-axis
angle, according to the literature with one such filter. Is the
relationship w2 = w1 / (cos a) where w1 is the on-axis wavelength,
a is the off-axis angle, and w2 is the off-axis pass wavelength?
That would require very careful alignment. Or is it something less
severe, and if so, what's the mechanism?
John Nagle