On Mon, 6 Dec 2004 16:40:19 -0000, "Leon Heller"
wrote:

"Robert Swinney" wrote in message
...
So Jim, what are the electronics for? I sorta figured the new LEDs used
(only) appropriate dropping resistors like older conventional LEDs.

Resistors waste power. The best way to get a lot of light out of LEDs is to
pulse them at a relatively high rate putting lots of current through them.
I've designed a flashing red LED beacon for a client (it's used in an alarm
system) that puts 250 mA through two strings of LEDs (0.5 A total) . They
are pulsed at 35 kHz using a small, very cheap microcontroller (25c in
quantity) with the power stored in an inductor being switched across them
with a MOSFET. Current taken from the supply is 10 mA. The whole thing is
on a tiny 30 mm by 45 mm PCB using mostly surface mount parts.

Leon

I seem to remember reading about pulsing LEDs to achieve higher
percieved brightness. But the LEDs would have a much shortened life
compared to running them at their rated current even though the
average current was the within spec. Wish that article was handy now.
Anybody know?
ERS