[200q20v] AC LEDs not showing up

Brett Dikeman brett at cloud9.net
Tue Oct 30 16:46:00 EST 2001

At 1:23 PM -0500 10/30/01, hah3 at mindspring.com wrote:

>or a little ripple because the battery isn't buffering as well? -
>that the LEDs don't like.

Most LEDs actually work "better" when pulsed.  If you look at a LED
traffic light, turn signal, etc, and it feels like something's
"wierd" about the way it looks...it's probably being pulse-driven,
and your brain's picking up on it.  The effect is most noticed when
the light switches on.

The reason for this(pulsing, not your brain :-) is heat; the die
becomes less efficient as it heats up, so they messed around with
pulsing it, and using higher voltage/current with each pulse...same
temps, but the additional juice, leads to a big jump in instantaneous
light output(and your brain fills in the rest.)  It's not as common
in new LED systems, since LED designers started getting smart and
building LEDs with more built-in heat-sink capabilities.

Incidentally, this pulsing is also what drives V1's absolutely nuts.
There's a road sign on the mass pike eastbound right after you go
under the hotel, that always made the V1 go bonkers, if I was in the
right lanes.

"They that give up essential liberty to obtain temporary
safety deserve neither liberty nor safety." - Ben Franklin
http://www.users.cloud9.net/~brett/bdikeman.asc	(PGP Public Key)

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