[sdiy] The Humble LED.

[Barry Klein]

Try this link: http://www.lumileds.com/
Do an Ebay search and you'll find these in small quantities.
But 30,000 mcd leds are commonplace now and much cheaper, and damn bright.
I just finished working with 8000mcd red and blue ones - check out my
contribution to storage technology by looking at the Western Digital
External Storage Combo Special Edition.  I did the lights....


Barry


-----Original Message-----
From: Batz Goodfortune [mailto:batzmanx at all-electric.com]
Sent: Friday, July 11, 2003 8:55 PM
To: synth-diy at dropmix.xs4all.nl
Subject: [sdiy] The Humble LED.


Y-ellow All.
         I have this crazy idea. I think it's been done before but for 
power saving rather than brightness. I want to get real light out of an 
array of LEDs. (Yellow in this case) I've pushed the array to the limits of 
reasonable reliability (IE:35mA per LED) but still it's not bright enough.

I would assume, rightly or wrongly, that heat is the killer with these 
devices as with many other semiconductor materials. I remember that one of 
the things Sinclair did when he (allegedly) invented the digital wrist 
watch, was to pulse the circuit. The LEDs were not on 100% of the time. 
Though I have no idea of the duty cycle. For him, it meant the same 
brightness but for a fraction of the battery usage. I'm thinking the
opposite.

In theory, should I not be able to pump significantly more current through 
the LEDs so long as that current was pulsed. Like a LED bike tail light. 
I'm thinking here about 50% duty cycle @ 3 or 4 Hz and pumped at between 60 
& 80mA per LED.

The reason I'm putting out this general question is that I can find no 
precedence for doing this. Other than some very expensive and specialized 
LED technology that's now kicking round.

Does anyone have any compelling evidence or caveats they'd like to share? 
I'd most appreciate it.

Strangely, this is the first time I've ever been able to feel any heat from 
a LED. Or should I say, a slight warmth. It's winter time and I can just 
feel a bit of a warmth in the glow. I guess I've been a fairly conservative 
LED user up until now but I'm also figuring that with every extra mA at a 
constant on-time, the reliability and longevity of the devices will be 
reduced. The only good thing about incandescent bulbs VS a LED array is 
that at least Bulbs are easy to change.

Anyway, before I go to all the trouble of building up a triple5 (or 
something), I just thought I'd ask if someone has any experience or 
knowledge of doing this kind of thing.

Thanks very much in advance.

Be absolutely Icebox.

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